In order to increase labor productivity, innovative mechanics use improved marking techniques and special devices.

Template marking It is usually used in the manufacture of large batches of parts of the same shape and size, but sometimes even small batches of complex products are marked using this method.

Figure 3.3.4.1 Marking using a template (B. S. Pokrovsky V. A. Skakun “Plumbing” Moscow 2003)

Templates are made from sheet material thick. 0.5... 1 mm, and for parts of complex shapes or with holes - 3...5 mm thick. When marking, the template is placed on a painted workpiece (part) and drawn with a scriber along the contour of the template, after which the score is marked. Using templates, it is convenient to mark holes for drilling, since this eliminates the need for geometric constructions - dividing segments and circles into parts, etc. .

The holes are marked according to the template using a scriber or center punch.

Sometimes the template serves as a guide, according to which the part is processed without marking. To do this, it is placed on the workpiece, then holes are drilled and the side surfaces are processed.

The feasibility of using a template is that marking work, which takes a lot of time, is performed only once when making the template. All subsequent marking operations represent only copying of the template outline.

Marking templates can also be used to control the part after processing.

Marking according to the sample differs in that it does not require the manufacture of a template. This method is widely used for repair work when dimensions are taken directly from a failed part and transferred to the material being marked. This takes wear and tear into account.

Marking in place More often used when assembling large parts. One part is marked on the other in the position in which they should be connected.

Marking with a pencil It is produced on a line on blanks made of aluminum and duralumin. Marking the latter with the help of a scriber is not allowed, since when applied, the marks are destroyed protective layer and conditions are created for corrosion to occur.

Accurate markings performed according to the same rules as usual, but more precise measuring and marking tools are used. The surfaces of the marked workpieces are thoroughly cleaned and covered with a thin layer of copper sulfate solution. It is not recommended to use chalk for painting, as it wears off quickly, sticks to your hands and contaminates the instrument.

When applying marks, they use a gauge with an accuracy of 0.05 mm, and the installation and alignment of the workpieces is carried out using an indicator. More accurate installation can be done by using plane-parallel length measures (tiles) and securing them in special holders. The marks are made shallow, and punching is done with a sharpened center punch with three legs located at an angle of 90° to each other.

The markings must exactly correspond to the dimensions indicated on the drawing; marking marks must be clearly visible, not erased during processing of the workpiece, and not deteriorate appearance and not reduce the quality of the part, i.e. the depth of the marks and core recesses must correspond technical requirements.

Marking is the application of points and lines to the materials to be processed or to the product being processed, indicating the axes and contours of the part according to the drawing, as well as the places to be processed.

The main purpose of marking is to indicate the boundaries to which the workpiece must be processed. The difference between the dimensions of the workpiece before and after processing is called processing allowance. However, in order to save time, simple workpieces are often processed without preliminary marking (for example, they are filed to the dimensions indicated in the drawing).

Sometimes two marks are applied: one to indicate the processing boundary, the other at some distance from it - for control.

There are planar and spatial markings. Using planar markings, flat parts or individual planes of parts are marked if they should not be linked to their other planes. Planar marking techniques are very similar to technical drawing techniques and are performed with tools similar to drafting ones.

Spatial marking consists in marking individual surfaces of a part located in different planes and under different angles to each other, are linked to each other. For spatial marking, the part is installed on a special marking plate, and the correctness of its installation is carefully checked.

When marking, the following tools are used (Fig. 4.2): rulers, meter, scriber, center punch, steel square, protractor, marking compass, caliper, surface planer, etc.

Rice. 4.2. Tools used for marking: a - scriber; b - mechanic's square; c - marking compass; g - surface planer; d - caliper.

Part marking can be done according to a drawing or a template.

Marking according to a drawing requires certain skills from the worker: a clear understanding of the drawing or sketch, the correct choice of the base from which the dimensions of the part are laid down, accurately setting the dimensions using a scale ruler and transferring them to the part to be marked.

Templates are usually used in markup large quantity flat parts and can significantly simplify and speed up the marking process itself. Templates are made from sheet steel, aluminum alloys or plywood. To mark a part using this method, the template is placed on the sheet to be marked, pressed against it and traced along the edges using a scriber. In this case, it is necessary to hold the scriber at a constant angle to the sheet, without tilting it towards the template (or ruler), since this distorts the dimensions of the part.

Usually, when drawing marks, the scriber is held with a double slope: one at 15-20° from the vertical away from the ruler (or template), the other in the direction of the scriber’s movement so that the angle between it and the workpiece (part) is 45-70°.

The mark should be carried out only once, and in order for it to be as thin as possible, the tip of the scribe should always be well sharpened.

To ensure that the lines drawn during marking are not erased during transportation and processing of the part, they are punched after 50-100 mm, and on curves - after 5-10 mm. The center punch is placed at the marked point first obliquely, and at the moment of impact it is brought to a vertical position (Fig. 4.3). The fingers of the hand holding the center punch should not touch the part being marked. The hammer strike is easy to apply.

Rice. 4.3. Punching techniques.

Nailing should be done after all marking is completed. It should be remembered that marking is one of the most critical operations that ensure correct production details. Therefore, the worker, when marking, must be careful, especially when determining the dimensions from the drawing, applying them to the workpiece, and also when installing the part on the marking plate. Marking should only be done with a serviceable and accurate tool.

The quality of the marking largely determines the accuracy of the part, and therefore the quality of the product as a whole. The marking must meet the following basic requirements:

1. exactly match the dimensions indicated on the drawing;
2. the marked lines (risks) must be clearly visible and not erased during processing of the part;
3. not spoil the appearance of the part, i.e. the depth of the marks and core recesses must comply with the technical requirements for the part.

When marking workpieces you must:

1. Carefully inspect the workpiece; if any holes, bubbles, cracks, etc. are found, they should be accurately measured and, drawing up a marking plan, measures should be taken to remove these defects during further processing (if possible).
2. Study the drawing of the part to be marked, find out the features and dimensions of the part, its purpose; mentally outline a marking plan (installation of the part on the slab, method and order of marking), Special attention pay attention to processing allowances. Machining allowances, depending on the material and size of the part, its shape, and installation method during processing, are taken from reference books.

   All dimensions of the workpiece must be carefully calculated so that after processing there are no defects left on the surface.

3. Determine the surfaces (bases) of the workpiece from which dimensions should be taken during the marking process. For planar marking, the bases can be the processed edges of the workpiece or the center lines, which are applied first. It is also convenient to take tides, bosses, and plates as bases.
4. Prepare surfaces for painting.

Used for coloring various compositions. Chalk diluted in water. For 8 liters of water take 1 kg of chalk. The composition is brought to a boil, then liquid wood glue is added to it at the rate of 50 g per 1 kg of chalk. After adding glue, the composition is boiled again. To avoid damage to the composition (especially in summer time) you can add a little linseed oil and drier to the solution. Black untreated workpieces are coated with this paint. Painting is done with paint brushes, but this method is not very productive. Therefore, whenever possible, painting should be done using sprayers, which, in addition to speeding up the work, provide uniform and durable painting.

Ordinary dry chalk. They rub the marked surfaces with it. The coloring is less durable. This method is used to paint the untreated surfaces of small non-critical workpieces.

Copper sulfate solution. Take three teaspoons of vitriol per glass of water and dissolve it. The surface, cleared of dust, dirt and oil, is covered with a vitriol solution with a brush. Deposits on the surface of the workpiece thin layer copper, on which marking marks can be easily applied. This method is used to paint only steel and cast iron workpieces with surfaces pre-treated for marking.

Alcohol varnish. Fuchsin is added to a solution of shellac in alcohol. This painting method is used only for precise marking of the treated surfaces of small products.

Quick-drying varnishes and paints are used to coat the surfaces of large machined steel and cast iron castings. Non-ferrous metals, hot-rolled sheets and profile steel materials cannot be painted with varnishes or paints.

Applying marks

The marks are applied in the following sequence: first, all horizontal marks are made, then vertical ones, after that - inclined ones, and lastly - circles, arcs and roundings.

When applying marks, use a scriber, pressing tightly against a ruler or square (Fig. 84) with a slight inclination away from the ruler and in the direction of movement of the scriber. The angle of inclination should be 75-80° and should not change during the process of applying marks, otherwise the marks will not be parallel to the ruler.

Rice. 84. Techniques for taking risks:
a - using a ruler, b - using a square, c - installing a scriber

Secondary drawing of the line is not permitted. On small workpieces, the marks are made along a square, and on large workpieces, along a ruler.

In the event that the marking line may disappear during processing, control marks are applied at a distance of 5-10 mm from it. To control the correct processing of the hole (drill withdrawal), a control circle with a radius larger than 2-8 mm is drawn around it. Control risks are not marked.

Marking marking lines

When working, take the punch with three fingers of the left hand, place the sharp end exactly on the marking line so that the tip of the punch is strictly in the middle of the mark (Fig. 85).

Rice. 85. Installation of center punch (a), kereeee (b)

First, tilt the center punch away from you and press it to the desired point, then quickly place it in a vertical position, after which a light blow is applied to it with a hammer weighing 100-200 g.

The centers of the cores must be located exactly on the marking lines so that after processing, half of the cores remain on the surface of the part. Be sure to place cores at the intersections of marks and roundings. On long lines (straight lines) cores are applied at a distance of 20 to 100 mm, on short lines, bends, curves and corners - at a distance from 5 to 10 mm. It is enough to mark the circle line in four places - at the intersections of the axes. Cores applied unevenly and not at the risk itself do not provide control. On machined surfaces of parts, cores are applied only at the ends of the lines. Sometimes on cleanly processed surfaces the marks are not punched, but extended to the side edges and punched there.

Marking techniques

Marking according to the drawing. Marking wrench(Fig. 86) are performed in the following sequence:

Rice. 86. Marking a wrench according to the drawing

1. study the drawing;
2. check the workpiece;
3. paint the marking areas with vitriol or chalk;
4. hammer a bar into the key mouth;
5. draw a center line along the key;
6. draw a circle and divide it into six parts;
7. perform the same operations for the second key head;
8. transfer all dimensions indicated in the drawing.

Template marking. To mark even small batches of complex products, it is advisable to use templates (Fig. 87).

Rice. 87. Marking according to a template

Templates are made one at a time or in a series from sheet zinc with a thickness of 0.5-1 mm or thin sheet steel, and in cases where the part has complex shape or row various holes, - 3-5 mm thick.

When marking, the template is placed on the painted workpiece and drawn with a scribe along the contour of the template.

Sometimes the template serves as a guide, according to which the part is processed without marking. To do this, the template is placed on the workpiece, then holes are drilled and the side surfaces are processed.

The feasibility of using a template is that marking work, which takes a lot of time, is performed only once when making the template. All subsequent marking operations represent only copying of the template outline. Marking templates can also be used to control the part after processing.

Marking with pencil. Such markings are made as with a scribe along a ruler on blanks made of aluminum and duralumin. It is not allowed to mark aluminum and duralumin parts using a scriber, since when marks are applied, the protective layer is destroyed and conditions are created for corrosion.

Precision marking is performed using the same techniques as regular marking, but more precise measuring and marking tools are used. The surfaces of the marked workpieces are thoroughly cleaned and covered with a thin layer of copper sulfate solution. It is not recommended to use chalk for painting, as it wears off quickly, sticks to your hands and contaminates the instrument.

When applying marks, a height gauge is used with an accuracy of 0.05 mm, and the workpieces are installed and aligned using an indicator. A more accurate installation can be obtained by using plane-parallel length measures (tiles), securing them in special holders. The marks are made shallow, and punching is done with a sharpened center punch with three legs located at an angle of 90°.

Marriage during marking

The most common types of marking defects are:

1. discrepancy between the dimensions of the marked workpiece and the drawing data, which occurs due to the inattention of the marker or the inaccuracy of the marking tool;
2. inaccuracy of setting the gauge on right size. The reason for such a defect is the carelessness or inexperience of the marker, the dirty surface of the slab or workpiece;
3. careless installation of the workpiece on the slab as a result of inaccurate alignment of the slab;
4. installing the workpiece on an uncalibrated slab.

Safety precautions

The stove must be installed securely. After work, protective plugs must be put on the surface scribers and proper equipment must be used.

Self-test questions

1. How do you choose bases when marking?
2. Make a plan for marking the workpiece according to the working drawing.
3. How to find the center of the hole when marking holes in cast workpieces?
4. When is template markup used?

Spatial marking in contrast to planar, it consists of drawing the contours of a part in several planes. Spatial marking is carried out according to drawings, templates, samples or on site. For spatial marking, along with the tools and devices used for planar marking, special tools are used: thickness gauges, height gauges, marking compasses, scales, squares, etc., as well as devices such as marking plates, prismatic and wedge-shaped pads, jacks, squares, etc. .

In Fig. 32 shows the simplest surface planer. Such surface gauges are used to perform most marking works. If the gauge is equipped with special measuring scales, then it is called a gauge gauge.

Rice. 32. The simplest survey:

1 - strip, 2 - base, 3 - screw, 4 - scriber, 5 - stand, 6 - screw with nut, 7 - coupling

Blanks (parts) for marking are installed on the marking plates and all fixtures and tools are placed. The slabs are cast from fine-grained gray cast iron. They have stiffening ribs in the lower part to protect them from bending under their own weight and the weight of the marked workpieces. The working parts of the slabs are precisely machined and scraped. On the upper plane of large slabs, longitudinal and transverse grooves are sometimes made at equal distances. The dimensions of the slabs are chosen so that the length and width of the marked workpiece is 400-500 mm less than the dimensions of the slab.

Very large slabs are made as composites of several slabs and are fastened together with bolts and dowels.

Small slabs are installed on tables or cast iron pedestals, heavier ones are placed on a brick foundation or on jacks placed on the foundation. Typically, the plates are placed in the most illuminated part of the room, where they are not affected by vibrations from operating equipment. Upper part The slabs are leveled.

The stove requires constant care. The surface of the stove must always be dry and clean, and after work it must be thoroughly cleaned, lubricated and covered. wooden shield. The stove should be washed with turpentine or kerosene at least once a week. work surface The marking plate is periodically checked using a straight edge and a feeler gauge. The gap between the ruler and the plate should not exceed 0.03-0.06 mm (depending on the size of the plate). The working surface of the scraped slab (for accurate marking) is checked for paint. The number of spots in a 25X25 mm square when checking must be at least 20.

When doing spatial markings, as well as when doing planar markings, first of all you should prepare the surfaces for marking. The preparation process includes leveling surfaces, eliminating local defects, cleaning from dirt and rust, and painting. Then determine best option install the workpiece on the slab and outline the sequence of applying marking marks. When spatial marking great importance It has right choice measuring bases.

The following rules for selecting bases are recommended: if the workpiece has at least one machined surface, then it should be selected as the base; if not all surfaces are treated, then the untreated surface is taken as the base; if external and internal surfaces are not processed, then they are taken as the base outer surface; When marking, all dimensions are applied from one surface or line taken as the base.

After selecting the measuring base, the workpiece is placed on the marking plate using devices so that one of its main axes is parallel to the working plane of the marking plate. There can be three such axes on a workpiece - length, height and width.

At spatial markings it is necessary to apply horizontal, vertical and inclined marks; the names of these marks are saved during the marking process for any rotation of the marked workpiece. To check the correct installation of the workpiece during further processing, control marks are applied to the workpiece, usually spaced 5-7 mm from the main marks and strictly parallel to them.

When marking spatially, horizontal marks are drawn with a surface gauge and a height gauge, lightly pressing its base against the marking plate and moving it along the workpiece. The surface gauge needle should be inclined towards the surface to be marked in the direction of movement at an angle of 75-80°. The pressure of the needle on the workpiece should be uniform.

Vertical lines can be marked in three ways: using a square with a wide base, its base is placed on the plate, and the narrow side is pressed against the workpiece and marked with a scriber; surface planer with workpiece rotation; surface planer using prisms.

Marking of inclined lines is carried out using rotary devices in a geometric construction at points, as well as using small tools, protractors and other devices.

Circular arcs are marked in the same way as with planar marking.

Painting the surface for marking. The marked surfaces are pre-painted so that the marks are clear. For painting, chalk, copper sulfate, quick-drying varnishes and paints, and shellac are used.

Chalk for coloring is diluted in water to a milky state, linseed oil and drier are added to the solution (for quick drying). Copper sulfate used in solution: 2-3 teaspoons per glass of water. Shellac is used in the form of an alcohol solution, tinted with magenta for color.

Marking work in plumbing are auxiliary technological operation consisting in transferring contour constructions according to the dimensions of the drawing to the workpiece.

Marking– this is an operation to apply lines (scores) to the surface of the workpiece,

defining the contours of the manufactured part, which is part of some

technological operations.

Planar marking used when processing sheet material and profile

rolled products, as well as parts on which marking marks are applied in one plane.

Planar marking consists of applying contour lines to a material or workpiece: parallel and perpendicular, circles, arcs, angles, various geometric shapes according to given dimensions or contours according to templates. Contour lines are applied in the form of solid marks.

In order for traces of the marks to remain until the end of processing, small depressions are applied to the marks using a punch, close to one another, or a control mark is applied next to the marking mark. Risks must be subtle and clear.

Spatial marking- This is the application of marks on the surfaces of the workpiece, interconnected by mutual arrangement.

Planar markings are made on the workpiece using a scriber. Accuracy at

marking is achieved up to 0.5mm. Marking marks with a scriber are carried out once.

The depth of the core recess is 0.5 mm. When performing practical

tasks, a scriber and a marking compass can be kept on a metalworking bench.

At the end of the work, it is necessary to remove dust and scale from the marking plate using a sweeping brush. When performing a practical task, you need to press the ruler against the workpiece with three fingers of your left hand so that there is no gap between it and the workpiece. When marking long marks (more than 150mm), the distance between the recesses should be 25..30mm. When punching short marks (less than 150mm), the distance between the recesses should be 10..15mm. Before setting the compass to the size of the arc radius, the center of the future arc must be punched. To set the compass to the size, you need to set one leg of the compass with its tip at the tenth division of the ruler, and the second at a division that exceeds the specified one by 10 mm. Angles, less

90º, measured with a goniometer using a square. For planar marking

parallel marks are applied using a ruler and a square. When marking on

plate of a circle of a given diameter, you need to set the compass to the size

exceeding the radius of the circle by 8..10mm.

To mark, measure and check the correct manufacture of products, the following tools are used: ruler, square, compass, vernier caliper, caliper, bore gauge, scale and pattern ruler, protractor, scriber, center punch, marking plate. Templates, patterns, and stencils are used as devices that speed up the marking process.

Scriber should be convenient for drawing clear lines on the marked surface and, together

in order not to spoil the working planes of the ruler or square. Scribler material

selected depending on the properties of the marked surfaces. For example,

The brass scriber leaves a clearly visible mark on the surface of the steel. At

marking parts from more soft materials it is advisable to take advantage

pencil. Before marking, it is better to apply a thin layer of water-based paint to the surface.

Center punches serve for marking the centers of circles and holes on marked

surfaces. Cores are made of solid steel. The center punch length ranges from 90

up to 150mm and diameter from 8 to 13mm.

As percussion instrument when making core holes, use

a plumber's hammer, which should be light in weight. Depending on

How deep should the core hole be? Hammers weighing from 50 to 200 grams are used.

Protractor steel with a protractor is used for marking and checking angles when

manufacturing of mating pipe assemblies, fittings and other parts

Air ducts.

Marking compass used for drawing circles,

arcs and various geometric structures, as well as for transferring

sizes from a ruler to a marking blank or vice versa. There are rack and pinion compasses,

thicknesser, calipers, internal calipers, vernier calipers.

Marking boards installed on special stands and cabinets with storage drawers

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marking tools and devices. Small marking plates are placed on tables. The working surfaces of the marking plate should not have significant deviations from the plane.

Various geometric figures applied to the plane with the same marking tool: ruler, square, compass and protractor. To speed up and

simplify planar marking templates made of sheet steel are used for identical products.

A template is placed on the workpiece or material and pressed tightly so that it does not move during marking. Along the contour of the template, lines are drawn with a scribe, indicating the contours of the workpiece.

Large parts are marked on the plate, and small parts are marked in a vice. If the product is hollow, for example a flange, then hammer it into the hole wooden cork and in the center of the plug a metal plate is fixed, on which the center for the leg of the compass is marked with a center punch.

The flange is marked as follows. The surface of the workpiece is painted with chalk, the center is marked and circles are drawn with a compass: the outer contour, the contour of the hole and the center line along the centers of the holes for the bolts. Often the flanges are marked according to a template, and the holes are drilled according to the jig without marking.