Part marking (general information). Benchmarking - marking Copy milling
Marking - the initial operation of the process of processing parts of the body. The layout receives sheets and profiles, the details of which will be cut on mechanical equipment, portable machines for thermal cutting or manual gas cutters. Marking can be done manually, using photoprojection, outline or template methods, on marking and marking machines with programmed control and using other methods.
The photoprojection method is used for marking sheet metal parts. With this method, negatives from large-scale drawings-templates are issued to the section of the shop marking. * The life-size marking of the contours of parts on the material is carried out according to the image from the negatives using special projection equipment.
The actual markup process is as follows. A metal sheet is served on a marking table. If the sheet does not lie on the table loosely (there are gaps between the sheet and the table top), then it is pressed against the table with clamps. The projection equipment is turned on, in which the corresponding negative is inserted in advance, and it is tuned. Since the lines and signs of the large-scale drawing are drawn in black ink, on the negative and its projection these lines and signs turn out to be light. On the light lines and signs on the surface of the marked sheet fix (core) the contours of the parts and their marking.
The sketch method of marking is used mainly for marking parts from profile steel. The use of this method for sheet metal parts is allowed only in cases of marking volumetric waste, the absence of photoprojection equipment and marking and marking machines.
The marking of parts with the help of sketches is reduced to the fact that the marker builds on the sheet or profile in full size the contours of the parts depicted in the sketches. The contours of the parts are obtained by performing simple geometric constructions using conventional measuring and marking tools. For marking the most complex parts, rails or templates are attached to the sketches, which is specially stipulated in the sketches. Both sketches and slats, as well as templates, come to the workshop markup area from the plaza.
Marking according to the patterns are subjected to parts having curved edges, the construction of which in a geometric way presents significant difficulties, as well as parts from bent profiles.
Mark the details according to the templates as follows. A template is laid on the sheet to be marked. After that, the outline of the part along the edges of the template is scribbled. Then they cut out all the cutouts on the template. Next, the template is removed and marked parts. After that, break lines, welds and all other lines necessary for processing and assembling parts are punched or plotted (according to the serifs made).
Fig. 11.5. Measuring tool: a - steel tape; b - folding meter; in - caliper; g - micrometer.
As a measuring tool when performing marking works, apply (Fig. 11.5):
- tape measures with a metal tape up to 20 m long, metal rulers up to 3 m long, folding meters for measuring lengths;
- calipers and calipers for measuring internal and external diameters, as well as material thickness with an accuracy of 0.1 mm;
- goniometers, protractors for measuring and building angles;
- micrometers for measuring the thickness of the material with an accuracy of 0.01 mm.
Fig. 11.6. Marking tool: a - compass; b - caliper; in - squares; g - marking center punch; d - control punch; e is a thread; Well - surface gage.
As a marking tool, apply (Fig. 11.6):
- compass and caliper for drawing circles and building perpendiculars;
- squares for building perpendiculars;
- cores for drawing points on metal;
- threads for drawing straight chalk lines;
- Thicknessers for parallel lines on the shelves of profile steel, etc .;
- scriber for drawing lines.
All dimensions applied to parts that do not have allowances must correspond to the plaz or drawing.
The following are the values \u200b\u200bof permissible deviations of the actual dimensions of the marked parts from the nominal (in millimeters):
From the overall dimensions for sheet parts:
with a length (width) of up to 3 m .............. ± 0.5
with a length (width) of more than 3 m ............ ± 1,0
From overall dimensions for profile parts:
with a length of up to 3 m .................. ± 1,0
with a length of more than 3 m ................. ± 2.0
From the size of cutouts for a set, etc. ........... 1,0
Diagonal difference ................... 2.0
From straightness or other shape of the edges:
with the length of the edges or chords (with curved edges) up to 3 m .................. ± 0.5
with the length of the edge or chord more than 3 m ........ ± 1,0
When marking, the width of the chalk line should not be more than 0.7 mm. The width and depth of the line drawn by the scriber should not exceed 0.3 mm.
When marking some parts along their edges, allowances are left. An allowance is a part of the metal removed from the workpiece to obtain parts in drawing or plaza sizes. The allowances are intended to compensate for possible deviations from the dimensions that arise during the processing of parts, assembly and welding of assemblies and sections. Values \u200b\u200bof allowances assigned from the conditions for the manufacture of parts are usually taken within 5-50 mm.
To save marking traces until the end of the processing and assembly of parts and restore marking (if necessary), all marking lines are closed.
Light alloy body parts are marked with a simple soft pencil. Punching of only the centers of the holes, the installation locations of the set (subject to mandatory further overlap by their welded parts), as well as contour lines that are removed during subsequent processing, is allowed.
For each marked part, a mark is necessarily applied.
The advent of automatic thermal cutting of parts allowed to exclude the operation of marking these sheets, but the marking of the parts remained. In order to automate the process of marking parts on production lines for thermal cutting of parts, marking machines with program control have been created. A prototype laser marking and marking machine has now been created.
* In detail about drawings-templates it was said in chap. 10.
The invention relates to techniques for gas-arc cutting, namely to air-plasma cutting of parts with a curved contour, mainly hoods of stamped parts, using a desktop and tooling and can be used in small-scale and pilot-industrial production at engineering plants. The part to be trimmed (2) is placed between the elements of a snap-in containing a lodgement fixed on the base of the working table and a template equipped with a handle and a guide along its contour. The plasma torch nozzle is abutted laterally into the guide and the part is trimmed along the outer contour of the guide by sliding the nozzle relative to the latter with the simultaneous orientation of the plasma torch axis perpendicular to the plane of the part being cut. The lodgement, the template and the trimmed part have a similar three-dimensional spatial form, providing conditions for their self-fixation among themselves. The contour of the lodgement is less than the contour of the template, and the contour of the latter is less than the contour of the workpiece of reference dimensions (1). As a lodgement and a template, ready-made parts of the same name are used, obtained by their standard trimming with subsequent processing of the edges. This will reduce the complexity of the process and the cycle time of trimming one part while ensuring the required geometric dimensions and quality of the trimmed edge. 8 ill.
The invention relates to techniques for gas-arc cutting, in particular to air-plasma cutting, and can be used at engineering enterprises in small-scale and pilot-industrial production.
Parts obtained, for example, by stamping, require circular trimming. In conditions of mass production, chipping dies are usually used, which is not always economically justified in small-scale and pilot-industrial production, since this requires significant capital investments. Automation of the process of trimming parts obtained by cold forming, for example, which are elements of the car body, presents certain difficulties, since they usually have a complex three-dimensional shape, which leads to the need for expensive and difficult to operate and maintain robotic systems and manufacturing equipment that provides spatial orientation of the trimmed part. In the case of a wide range of trimmed parts, frequent changes in equipment and readjustment of process parameters are necessary.
In small-scale and pilot-industrial production, manual cutting of each part by mechanical means requires preliminary marking, it is time-consuming and inefficient. Cutting with scissors leads to deformation of the trimmed edges and the need for their subsequent editing.
Compared to manual cutting with scissors, air-plasma cutting avoids mechanical deformation of the edge and, as a consequence, subsequent editing operations.
Plasma cutting can be carried out using a template or equipment, excluding preliminary marking, while the complexity of trimming volumetric body parts is significantly reduced, and productivity is increased.
For the convenience of cutting products with a complex spatial orientation, the product has to be installed in various positions with the help of devices, one of which is, for example, a positioner - a device designed to install the product in a spatial position convenient for cutting. Typically, the positioner does not move the product at a welding speed, but only holds it in a predetermined position.
A known method of fixing the part during welding, which consists in the fact that the part in the position of welding is held by several clamps and after welding it is transferred to the control position, in which the actual position of the specified control points on it is determined. The position of these points is compared with their reference location, and if deviations from the reference location are detected, deviations are compensated by changing clamps to eliminate the error when welding the next part [US Patent No. 6173882, cl. B 23 K 31/12, B 23 K 26/00, 2001].
This method does not provide conditions for an error-free conduct of the welding process itself, and also requires additional time for monitoring and readjustment.
A known method of trimming parts, taken as a prototype, providing for air-plasma cutting of these parts along the contour using the desktop and equipment [Automated installation of air-plasma cutting for the manufacture of car body parts. Nesterov V.N., Truck and bus, trolleybus, tram. 2001, No. 1, p. 34-35].
This method can be used in serial and mass production, but it is complex and expensive.
The problem to which the claimed invention is directed is to develop such a trimming method in which it would be possible to reduce the complexity of the process and the cycle time of trimming one part while ensuring the required geometric dimensions and quality of the trimmed edge.
This problem is solved by the fact that in the method of trimming parts, mainly hoods of stamped parts, including air-plasma cutting of these parts along the contour when using a plasma torch with a nozzle, a work table and equipment, the part to be trimmed is placed between elements of a tool holder containing a lodgement fixed on the base of the worker the table, and the template, equipped with a handle and a guide along its contour, rest the nozzle of the plasma torch on the side in the guide and actually cut the part along the outer contour of the guide by the nozzle slides relative to the latter with the simultaneous orientation of the plasma torch axis perpendicular to the plane of the part being cut, while the lodgement, the template and the part being cut have a similar spatial and spatial shape that ensures their self-fixation with each other, the lodgement contour is smaller than the template contour, and the contour of the latter is less than the part contour reference sizes, moreover, as a lodgement and a template, ready-made parts of the same name are used, obtained by their standard trimming with subsequent processing of the edges.
Placing the part to be trimmed between the tooling elements containing the tool holder fixed on the base of the working table and the template provided with a handle and a guide along its contour, as a whole, allows you to rigidly fix the part and provide the necessary conditions for the trimming process.
The use of a tool tray as a tooling element provides support for fixing (fixing) and stable spatial orientation of the part to be trimmed.
Fixing the tool tray on the base of the desktop allows you to get a convenient position for trimming the part.
The use of a template as a tooling element ensures that after trimming the part with outlines corresponding to the outline of the drawing, the template itself is used as a device used directly in the trimming process, and not for preliminary marking.
Supplying the template with a handle allows you to quickly install it on the part before trimming, and after the end of the cycle, quickly remove it without the risk of temperature.
The supply of the guide template along its contour provides the conditions for the lateral stop of the plasma torch nozzle in the guide and sliding relative to it during the cutting process.
The abutment of the nozzle of the plasma torch from the side into the guide of the template allows cutting without practically oscillating the nozzle, that is, with the spatial orientation of the plasma torch at each point of the path (contour) of the cut.
Trimming the part along the outer contour of the guide by sliding the nozzle of the plasma torch relative to the latter ensures reproducibility of the cut path (contour).
The simultaneous orientation of the axis of the plasma torch perpendicular to the plane of the part to be cut ensures the quality of the cut with minimal slopes, burns, burrs, etc.
The use of a lodgement, a template and a trimmed part with a similar spatial-spatial form, providing the conditions for their self-fixation among themselves, eliminates the need for additional devices.
The similarity of the lodgement, the template and the part to be trimmed to each other means that each of them can be obtained from the other by increasing or decreasing the linear dimensions in the same respect.
Making the lodgement contour smaller than the contour of the template, and the contour of the latter smaller than the contour of the part of the reference dimensions allows you to take into account the dimensions of the plasma torch used when cutting the part, thereby providing conditions for accurate reproduction of the contour of the part when it is trimmed (using the template), and also not impede passage cutting products and provide a stable spatial orientation of the trimmed part in a position convenient for trimming (use of a tool tray).
The use of finished parts of the same name as a template and tool tray by means of their standard trimming with subsequent processing of the edges makes it possible to obtain samples from these parts that can serve as a standard for small-scale and serial reproduction of the same parts, and to ensure high accuracy of this process during trimming.
The proposed method is illustrated by drawings, which depict:
figure 1 - outline of the finished part 1, for example, the base of the rear seat of the car, a plan view;
figure 2 - exhaust circuit 2 of the stamped part in comparison with the contour of the finished part, indicated by a dotted line, a plan view;
figure 3 - contour lodgement 3 made of serial parts, in comparison with the contour of the finished part, indicated by a dotted line, a plan view;
figure 4 - contour of the template 4, made from a serial part, in comparison with the contour of the finished part, indicated by a dotted line, and the contour of the lodgement, indicated by a dot-dot line, a plan view;
figure 5 - elements of the assembly tool with trimmed part before their mutual fixation, where the position 5 denotes the base of the desktop, and the position 6 is the handle of the template;
figure 6 - the same, in a fixed position, the plasma torch is not shown;
in Fig.7 - view A in Fig.6, before the operation of the plasma torch, where the position 7 denotes the guide template, 8 is the plasma torch, 9 is the axis of the plasma torch;
on Fig - the same, when the plasma torch, where the position 10 indicates the electrode, and 11 is a plasma-forming nozzle.
The method of trimming parts with a curved contour is as follows.
The lodgement 3 (Figs. 5 and 6), made in accordance with the method, is attached to the base 5, which is a platform, inside the contour of which there are means for securing the lodgement holder (not shown), and in a position that provides the most favorable (optimal) conditions for the operator. Next, the trimmed part 2 is applied to the lodgement 3 and fixed on it, and then the template 4 is applied from above, after which the plasma torch 8 (Fig. 7) is brought to the part 2, its nozzle rests on the side into the guide 7 of the template 4, and the part is trimmed along the outer contour guide by sliding the nozzle relative to it with the simultaneous orientation of the axis 9 of the plasma torch perpendicular to the plane of the cut part.
With a correctly selected speed of movement of the torch, the width of the cut is uniform and amounts to 1.0-2.0 of the diameter of the plasma forming nozzle 11 (Fig. 8), and the edges are clean, with minimal bevels and practically no gratings.
After the equipment is manufactured, it is used to trim the installation (experimental) batch of parts, which is then transferred to metrological measurements to verify the compliance of geometric and other parameters with the requirements of design documentation. If this conformity is established and confirmed, then this part is considered the standard, and the process is standardized. In the future, if necessary, the standardization can be repeated with a frequency determined by the technology.
The application of the invention allows in a short time and at minimal cost to organize the process of trimming parts of complex shape.
Example. The hoods of stamped parts were cut along the contour using a manual air-plasma cutting machine of the DS-90P type (NPP Tekhnotron, Russia) equipped with a PSB-31 plasmatron (f. Alexander Binzel, Germany), in which the outer diameter of the nozzle part was 11 , 0 mm, the diameter of the plasma forming nozzle is 1.0 mm. The value of the displacement of the guide was calculated by the formula:
Δ \u003d 1/2 (d N.c. - (1.0-2.0) d P.c.),
where Δ is the amount of displacement;
d n.c. - the outer diameter of the nozzle part;
d P.c. - the diameter of the plasma forming nozzle.
The coefficient (1.0-2.0) takes into account the change in the width of the cut depending on the wear (erosion) of the plasma-forming nozzle 11 (Fig. 8), the electrode 10 and the parameters of the cut (speed, current).
In our example, Δ min \u003d 1/2 (11-1.0) \u003d 5.0 mm, Δ max \u003d 1/2 (11-2.0) \u003d 4.5 mm, i.e. in nominal, you can select the offset value Δ \u003d (4.75 ± 0.25) mm.
The calculation is illustrated in Fig. 8.
On the base of the working table, a tool tray 3 was placed, obtained by cutting 30 mm from the edge of the part (\u003e 5 mm), a trimmed part 2 was fixed on it, and a template 4, obtained by cutting 4.75 mm from the edge of the part was placed on top (taking into account the size used plasmatron). After the assembly was completed, the hood 2 was trimmed, maintaining lateral contact of the outer generatrix of the nozzle part with the guide 7 on the template 4 along its contour, supporting the plasma torch nozzle on the part to be cut with the simultaneous orientation of the plasma torch axis 9 perpendicular to the plane of this part.
Not all machine parts have contours outlined in straight lines, similar to those discussed in previous chapters; many parts represent flat surfaces bounded laterally by curved contours. In fig. Fig. 222 shows parts with curved contours: a wrench (Fig. 222, a), a clamp (Fig. 222,6), a cam to a turning machine (Fig. 222, c), a connecting rod of the engine (Fig. 222, d).
The curvilinear contour shown in Fig. 222 parts consists of straight segments, conjugated with curves or with arcs of circles of various diameters, and can be obtained by milling on a conventional vertical milling machine or a special copy-milling machine.
Curved path millingon a vertical milling machine can be carried out: for marking by combining manual feeds, for marking with a round rotary table and a copy.
Milling a curved contour by combining manual feeds. Milling by combining manual feeds consists in the fact that the pre-marked workpiece (fixed either on the table of the milling machine, or in a vice, or in a special device) is processed with an end mill, moving the table by manual feed simultaneously in the longitudinal and transverse directions so that the cutter removes the metal layer in accordance with the marked curved contour.
Consider the example of milling by marking by combining manual feeds of the contour of the bar shown in Fig. 223.
The choice of cutters.For milling, we choose an end mill, the diameter of which would make it possible to obtain a rounding of R \u003d 18 mm, required by the drawing. We take an end mill with a diameter of 36 mm with six teeth. The material of the cutter is high-speed steel.
Preparing for work. The bar is installed directly on the table of the vertical milling machine, securing it with tacks and bolts, as shown in Fig. 224. A parallel lining is used so that the cutter during processing does not touch the working surface of the machine table.
When installing, make sure that chips or dirt do not get between the contacting surfaces of the machine table, lining and parts.
Setting the machine to cutting mode. Since for our case the feed is carried out manually, we take it equal to 0.08 mm / tooth, considering the cutting depth of 5 mm. According to the table 211 of the “Manual of a young milling machine operator” for these conditions, the recommended cutting speed is 27 m / min and the corresponding number of mill revolutions is n \u003d 240 rpm.
We select the closest number of revolutions available on the machine and set the speed box limb at n \u003d 235 rpm, which corresponds to a cutting speed of 26.6 m / min.
Contour milling. We will carry out milling with manual feed, following the marking, for which we will begin processing from the area where there is the smallest allowance, or we will embed gradually, in several passes, in order to avoid breakage of the cutter.
Milling is performed by simultaneous feeding in the longitudinal and transverse directions, respectively, of the marking line. It is not possible to mill a contour cleanly in one pass, therefore, first a curved contour is milled rough, and then cleanly along a marking line, including rounding off at a wide part of the bar.
Milling the central groove 18 mm wide and 50 mm long is carried out according to the method of milling a closed groove (see Fig. 202).
Curved contours having the shape of a circular arc in combination with straight line segments or without them are processed on a round turntable (see Figs. 146 and 147).
When machining on a round rotary table, an arc contour is formed without combining two feeds as a result of a circular feed of the rotary table, and the accuracy of the contour here does not depend on the ability to combine two feeds, but on the correct installation of the workpiece on the table.
Consider an example of milling a part that combines the processing of the outer contour with the processing of internal circular grooves.
Let it be necessary to process the contour pattern shown in Fig. 225.
The blank has the form of a rectangle with a size of 210 × 260 mm and a thickness of 12 mm. A central hole with a diameter of 30 mm (for fixing it on a round table) and four auxiliary holes with a diameter of 30 mm (for milling) were pre-drilled in the workpiece. The part outline is marked on the workpiece.
Milling will be carried out on a vertically milling machine. Since external and internal contours are subject to processing, milling must be performed in two installations:
1. Having fixed the workpiece on the round table with bolts passing through any two holes on the workpiece, we mill the external contour according to the marking using the rotational movement of the round table (Fig. 226, a).
2. Having fixed the workpiece on the round table with clamping bars, we mill the internal circular grooves according to the marking, using the rotational movement of the round table (Fig. 226,
Since the processing of the external contour and internal grooves is desirable to be performed without changing the cutter, we select an end mill made of high-speed steel with a diameter of 30 mm corresponding to the width of the circular groove.
Before installation, the round table must be placed on the edge and wipe its base. Then insert clamping bolts with nuts and washers on both sides of the machine table and fasten the round table with bolts. To base the workpiece, it is necessary to insert a centering pin with a diameter of 30 mm into the central hole of the round table.
We fix the workpiece with a centering pin and bolts during the first installation (Fig. 226, a) and a centering pin and clamps during the second installation (Fig. 226, b).
Setting the machine to milling mode. Choose the cutting speed according to the table. 211 of the “Handbook of a young milling machine operator” for a mill with a diameter of 30 mm and feed for £ tooth \u003d 0.08 mm / tooth, with the largest cutting depth t \u003d 5 mm. Cutting speed v \u003d 23.7 m / min and, accordingly, n \u003d 250 rpm.
We adjust the machine to the nearest number of revolutions p \u003d 235 rpm, which corresponds to a cutting speed of v \u003d 22.2 m / min, and proceed to the processing of the outer contour.
Having fixed the end mill in the machine spindle, turn on the machine and bring the part to the mill in the place where there is the smallest allowance (Fig. 226, a).
The rotary cutter is cut by manual feed into the workpiece to the marking line and, by turning on the mechanical longitudinal feed, the straight section 1-2 is milled (Fig. 225). With manual rotation of the round table, a curved section 2-3 of the outer contour is milled. After that, with a mechanical longitudinal feed, a rectilinear portion 3-4 of the outer contour is milled, and finally again, with a manual rotation of the round table, a curved portion 4-1 of the outer contour is milled.
Installation of the workpiece for milling circular grooves is performed as shown in Fig. 226 b.
By rotating the handles of vertical, longitudinal and transverse feeds, a mill is brought (see Fig. 226, b) and inserted into hole 5 (see Fig. 225). Then they raise the table, lock the console of the table and smoothly manually rotate the round table, slowly rotating the handwheel, mill the internal groove 5-6. At the end of the passage, lower the table to its original position and bring the cutter out of the groove. By turning the knobs of the circular and vertical feeds, a mill is introduced into the hole 7 and the inner groove 7-8 is milled in the same way by a circular feed.
Copy milling. Milling of parts having a curved contour, curved grooves and other complex shapes can be performed, as we have seen, either by combining two feeds, or by using a rotary round table; in these cases, preliminary marking is required.
In the manufacture of large batches of identical parts with a curved contour, special copying devices are used, or special copy-milling machines are used.
The principle of operation of copying devices is based on the use of longitudinal, transverse and arc feed of the machine table to communicate to the workpiece a curvilinear movement that exactly matches the contour of the finished part.
To automatically obtain this contour, copiers are used, i.e. templates that replace the markup. In fig. 227, b shows the milling of the contour of the large head of the connecting rod of the engine. The copier 1 is placed on part 2 and securely fastened with it. Acting with the handwheel of the circular feed of the round turntable and the handles of the longitudinal and transverse feeds, the milling machine ensures that the neck 3 of the end mill is constantly pressed to the surface of the copier 1.
copy processing,
The end mill used for is shown in fig. 227, a.
In fig. 228 is a diagram of a copying device for milling the contour of a large head of a connecting rod of an engine similar to that shown in Fig. 227, but with the use of, except for the copier, another roller and cargo. Under the action of the load 1, the roller 2 is always pressed against the copier 5, rigidly connected to the table of the copying device 5, on which the machined connecting rod is fixed 4. The mill 3 will describe the curved path corresponding to the contour of the large connecting rod head, if, using a circular feed, we will rotate a round rotary table .
Before you cut a part from a sheet, you need to mark its contours in exact accordance with the dimensions indicated in the drawing.
The following types of markup are distinguished:
1. Marking according to the template in the manufacture or assembly of a large number of homogeneous parts.
2. Marking with a marking tool. This type of markup, in turn, can be divided into:
- marking with a ruler and compass;
- marking using the outline for bending and flanging the edges, as well as for trimming the edges;
- marking with centering before drilling holes;
- marking using a surface gage.
Marking when assembling nodes and installing them on an airplane is performed using both a marking tool and templates.
Marking tool
Steel ruler, steel meter, scriber, pencil (simple), square, outline, compass, center punch, hammer, templates, protractor, surface gage, prisms, goniometer, plumb.
Layout the contour of a part according to a template
1. Place the template on the sheet so that when cutting out the details from it, as little waste as possible is obtained.
2. Mark the part by drawing a sharp scribble around the outline of the template (Fig. 13).
Marking a part with a marking tool
a) Marking with a ruler and compass
Mark a part with rectilinear contours, drawing parallel lines
1) draw a vertical line a parallel to the sheet edge using a steel ruler;
2) draw a line b using a square at a right angle to line a;
3) apply strokes for drawing contour lines parallel to the sides a and b, laying the dimensions according to the drawing in full size (Fig. 15 and 16);
4) draw lines on the outlined strokes (Fig. 17 and 18);
fig. 17-fig. eighteen.
5) apply strokes in the same way for internal lines (Fig. 19) parallel to sides a and b.
Mark part with rectilinear and curved contours
1) draw an axial vertical line;
2) set aside from the center line to the right and left half the length of the lower straight line;
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Drawing Basics
You already know that for the manufacture of any product you need to know its device, the shape and dimensions of the parts, the material from which they are made, methods of connecting parts to each other. You can learn all this information from drawing, sketch or technical drawing.
Drawing
- this is a conditional image of the product, made according to certain rules using drawing tools.
The drawing shows several types of products. Views are performed based on how the product is observed: front, top or left (side).
The name of the product and parts, as well as information on the quantity and material of the parts, is entered in a special table - specification.
Often the product is depicted enlarged or reduced compared to the original. But despite this, the dimensions on the drawing are real.
A number that shows how many times the actual sizes are reduced or increased is called scale
.
The scale cannot be arbitrary. For example, for increase
accepted scale 2:1
, 4:1
etc., for decreasing
-1:2
, 1:4
etc.
For example, if the inscription " M 1: 2
", Then this means that the image is half the actual size, and if" M 4: 1
", Then four times more.
Often used in production sketch
- hand-drawn image of the subject according to the same rules as the drawing, but without observing the exact scale. When drawing up a sketch, the ratio between the parts of the subject is preserved.
Technical drawing - visual image of the item, made by hand in the same lines as the drawing, indicating the dimensions and material of which the product is made. It is built approximately, by eye, maintaining the relationship between the individual parts of the subject.
The number of views in the drawing (sketch) should be such as to give a complete picture of the shape of the subject.
There are certain rules for sizing. For a rectangular part, dimensions are applied as shown in the figure above.
The size
(in millimeters) put down from the dimension line from left to right and from bottom to top. The name of the unit of measure is not indicated.
Part thickness
denoted by a latin letter S; the figure to the right of this letter shows the thickness of the part in millimeters.
The designation on the drawing also applies to certain rules. hole diameter
- it is designated by a symbol Ø
.
Circle radii
denoted by a latin letter R; the figure to the right of this letter shows the radius of the circle in millimeters.
Detail outline
on the drawing (sketch) must be shown solid thick main lines (lines of the visible contour); dimension lines
- solid thin; invisible outline lines
- dashed; axial
- dot-and-dash etc. The table shows the different types of lines used in the drawings.
|
Read the drawing, sketch, technical drawing - means to determine the name of the product, the scale and image of the species, the size of the product and individual parts, their name and quantity, shape, location, material, type of connection.
Technical documentation and harmonization tools
Technical documentation for the manufacture of a simple one-part, multi-part or complex product includes:
picture
finished product, specification and brief information about the function ( F), constructions ( TO), technologies ( T) and decoration (aesthetics) ( E) of this object of labor - the first sheet;
scheme
possible options for changing the overall dimensions and configuration of the product or its parts. The proposed changes are based on various systems of correlation and division of forms - the second sheet;
detail drawings
complex configuration, which are made according to the templates - the third sheet (not for all products);
illustrative technological map
containing information about the sequence of manufacturing of parts or the product itself in the form of operational drawings and about tools and devices used in this operation, the following sheets. Their contents can be partially changed. These changes relate mainly to the use of special technological devices to speed up the execution of certain operations (marking, sawing, drilling, etc.) and to obtain better parts and products.
The development of the design of any product, the appearance of which has certain aesthetic requirements, is associated with the use of certain laws, techniques and means of composition. Ignoring at least one of them leads to a significant violation of the form, making the product inexpressive and ugly.
Most often, harmonization tools such as proportionality (finding the harmonic relationship of the sides of the product), subordination and dismemberment of the form.
Proportionality - this is the proportionality of the elements, the most rational ratio of parts between each other and the whole, giving the subject harmonic integrity and artistic completeness. Proportions establish a harmonious measure of parts and the whole with the help of mathematical relations.
A system of rectangles with a proportional aspect ratio can be constructed using:
but) integer relations from 1 to 6 (1: 2, 1: 3, 1: 4, 1: 5, 1: 6, 2: 3, 3: 4, 3: 5, 4: 5, 5: 6) (Fig. 1) ;
b) the so-called golden ratio". It is determined by the formula a: b \u003d b: (a + b). Any segment can be proportionally divided into two unequal parts in this regard (Fig. 2). Based on this relationship, you can build or dismember the sides of the rectangle (Fig. 3);
at) proportional seriesmade up of the roots of natural numbers: √2, √3, √4 ”√5. You can build a system of rectangles of this series as follows: on the side of the square “1” and its diagonal “√2” - a rectangle with an aspect ratio of 1: √2; on the diagonal of the latter - a new rectangle with an aspect ratio of 1: √3; then the rectangle is 1: √4 (two squares) and 1: √5 (Fig. 4).
To find the harmonic aspect ratio use the system subordination and dismemberment of the form:
but) subordination it is applied when another, proportionate to the main part is attached to some element (Fig. 5);
b) the dismemberment is used when it is necessary to divide the main form into smaller elements (Fig. 6).
Below are options for changing the configuration of the shape of the products and options for changing the overall dimensions, in which the above harmonization rules are used.
Marking rectangular parts
The purpose and role of the markup. The process of applying contour lines to the future workpiece on wood is called marking. Markup - one of the most important and time-consuming operations, on the performance of which not only the quality of the products, but also the cost of the material and working time largely depends. Marking before sawing is called preliminary or marking up rough blanks.
In production, preliminary marking is carried out taking into account processing allowances and shrinkage. In training workshops, dried materials are processed, therefore, allowances for shrinkage are not taken into account.
You should be aware that when processing dried workpieces, a surface with a low roughness is obtained and high adhesion and finish are achieved. Grinding allowances on the one hand, the details of planed surfaces are 0.3 mm, and for parts whose surfaces are sawn, - not more than 0.8 mm. Allowances for planing wood-fiber boards and glued plywood are not provided, as they are not subject to planing.
Markup perform in pencil using marking tools (measuring ruler, joiner's square, surface gage, malka, tape measure, vernier caliper, etc.) in accordance with the drawing, sketch, technical drawing. A general view of some marking tools is shown below.
Marking and measuring tools. As you already know, the marking of wood and wood materials is carried out with various tools, most of which are also used for measurements in the manufacturing process of parts: roulette - for measuring and marking saw and timber; meter- for marking rough blanks; ruler - for measuring parts and blanks; square - for measuring and plotting rectangular parts; nonsense - for drawing and checking angles of 45 ° and 135 ° and when marking joints on the "mustache"; malka- for drawing and checking various angles (a given angle is set by the protractor); surface gage and bracket - for drawing parallel lines when processing edges or layers of workpieces; compass - for drawing arcs, circles and deferring sizes; calipers - to determine the diameter of round holes; caliper - for measuring the diameter of the holes.
From precision markup product quality depends. Therefore, be careful when working. Try to keep the marking so that as many parts as possible are obtained from one workpiece.
Do not forget about allowance. Allowance
- a layer of wood that is removed during processing of the workpiece (when sawing, they usually give an allowance of up to 10 mm, with planing - up to 5 mm).
When marking a rectangular piece of plywood (Fig. but
) do this:
1. Choose base edge blanks (if there is no such edge, then it should be cut according to previously applied on a ruler baseline).
2. A line is drawn along a square at right angles to the base edge (line) at a distance of about 10 mm from the end (Fig. b
)
3. The length of the part is laid off from the drawn line along the ruler (Fig. at
).
4. A line is drawn along the square limiting the length of the part (Fig. g
).
5. On the ruler, lay the width of the part on both lines, limiting the length of the part (Fig. d
).
6. Connect both received points (Fig. e
).
If the part is made of a board or bar, then the marking is made from the most even and smooth layers and edges (if they are not there, then the front layer and edge are pre-strapped). Front surfaces on the workpiece are marked with wavy lines.
Subsequent markup is performed as follows:
1. The width of the part is laid off from the front edge and a marking line is drawn with a pencil (Fig. A).
2. The thicknesser rail is extended so that the distance from the tip of the stud to the shoe is equal to the thickness of the part (Fig. B).
3. Using a thickness gauge, mark the thickness of the part (Fig. C).
4. Mark the length of the part using a ruler and a square (Fig. G).
The marking of a large number of identical parts or parts having a curved contour is carried out using special patterns
. They are made in the form of plates having the same shape as the outline of the product.
Mark out the details with a simple and sharpened pencil.
When marking, the template should be firmly pressed to the workpiece.
The process of manufacturing wood products
In training workshops, they learn to make various products from lumber and plywood. Each of these products consists of individual parts connected together. Parts can have a different shape. First they try to make flat rectangular parts. To do this, you need to correctly select the workpiece (bar, board, plywood sheet), learn how to perform marking, planing, sawing, stripping. After the manufacture of all parts, the assembly and decoration of the product is carried out. Each of these work steps is called operation .
Each operation is performed by a specific tool, often using fixtures . So-called devices that facilitate the work and make it better. Some devices help, for example, quickly and reliably fasten a part or workpiece, tools, others accurately mark out, without errors to perform this or that operation. It is advisable to use the devices in the case when you need to make a large number of identical parts. You are already familiar with one of the fixtures - the clamp of a carpentry bench.
In the training workshop, you will most often work on technological map which indicates sequence of operations . Below is a flow chart of the manufacture of a kitchen board.
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Technological maps used in production indicate all operations, their components, materials, equipment, tools, the time required to manufacture the product, and other necessary information. In school workshops, simplified technological maps are used. They often use various graphic images of products (technical drawings, sketches, drawings).
The finished product will be of high quality if it meets the dimensions and requirements indicated on the drawing.
To obtain a high-quality product, it is necessary to hold the tool correctly, observe the working position, accurately perform all operations, constantly monitor yourself.