Flat marking is the deposition of flat blanks on the surface of sheet and strip metal, as well as on the surfaces of cast and forged parts of various lines.

Flat marking is used in the processing of sheet material and profiled steel, as well as parts on which marking risks are applied in the same plane.

Various marking methods are used: according to the drawing, template, sample and in place. The choice of marking method is determined by the shape of the workpiece, the required accuracy and the number of products. The accuracy of the markup greatly affects the quality of processing.

Tool and fixtures

Used in the markup, are combined into three main groups:

• 1) a tool for applying and wrapping pictures - scribes, surface guides, calipers, spring compasses, calipers, center punches; tool for finding centers of parts - center-center detector, square-center detector, protractor-center detector, special devices for marking parts with large holes;
• 2) devices for marked blanks - pads, jacks, rotary devices, vertical racks for measuring rulers, additional planes to the marking plate, dividing devices and center headstock, box-shaped and equipped with stiffeners inside.

In order for the marking risks to be clearly visible on the surface of the marked workpiece, this surface should be painted, i.e. cover with a composition whose color is contrasted with the color of the material of the marked workpiece. For painting marked surfaces use special compositions.

Materials for painting surfaces are selected depending on the material of the workpiece that is being marked, and on the state of the surface being marked. For painting marked surfaces use: a solution of chalk in water with the addition of wood glue, which provides reliable adhesion of the coloring composition to the surface of the marked workpiece, and desiccant, contributing to the rapid drying of this composition; copper sulfate, which is copper sulfate and, as a result of chemical reactions, ensures the formation of a thin and strong layer of copper on the surface of the workpiece; quick-drying paints and enamels.

Markup  - the operation of applying marking lines (marks) to the workpiece, which determine the contours of the future part or place to be processed. The marking accuracy can reach 0.05 mm. Before marking, it is necessary to study the drawing of the marked part, to find out the features and dimensions of the part, its purpose. The marking must meet the following basic requirements: exactly match the dimensions indicated on the drawing; marking lines (risks) should be clearly visible and not erased during the processing of the workpiece. To install the parts to be marked, scribes, pads, jacks and rotary devices are used. For marking use scriber, punch, marking vernier calipers and surface gages. Depending on the shape of the marked blanks and parts, planar or spatial (volume) marking is used.

Flat marking  perform on the surfaces of flat parts, as well as on strip and sheet material. When marking, contour lines (risks) are applied to the workpiece according to specified sizes or according to templates.

Spatial marking  most common in mechanical engineering and significantly different from planar. The difficulty of spatial marking is that you have to not only mark the surfaces of the part located in different planes and at different angles to each other, but also link the markup of these surfaces to each other.

Base - a base surface or baseline from which all sizes are measured during marking. It is chosen according to the following rules: if the workpiece has at least one machined surface, it is chosen as the base; in the absence of treated surfaces at the workpiece, the outer surface is taken as the base.

Preparation of blanks for marking  It starts with cleaning it with a brush from dirt, scale, corrosion. Then the workpiece is cleaned with sanding paper and degreased with white spirit. Before painting the surface to be marked, it is necessary to make sure that there are no shells, cracks, burrs or other defects on the part. To paint the surfaces of the workpiece before marking, the following compositions are used: chalk, diluted in water; ordinary dry chalk. Dry chalk is rubbed onto the marked untreated surfaces of small non-responsible blanks, since this color is fragile; solution of copper sulfate; alcohol varnish is used only for precise marking of the surfaces of small products. The choice of a coloring composition for application to the base surface depends on the type of material of the workpiece and the method of its preparation: the raw surfaces of workpieces made of ferrous and non-ferrous metals obtained by forging, stamping or rolling are painted with an aqueous chalk solution; the treated surfaces of the ferrous metal blanks are painted with a solution of copper sulfate, which, when interacting with the material of the blank, forms a thin film of pure copper on its surface and ensures clear marking marks; the treated surfaces of non-ferrous metal blanks are painted with quick-drying varnishes.

Markup methods

Template marking is used in the manufacture of large batches of identical parts in shape and size, sometimes for marking small batches of complex workpieces. The marking on the sample is used during repair work, when the dimensions are taken directly from the failed part and transferred to the marked material. At the same time, wear is taken into account. The sample differs from the template in that it has a one-time use. Marking in place is carried out when the parts are mating and one of them is connected to the other in a certain position. In this case, one of the parts acts as a template. Marking with a pencil is made on a ruler on blanks of aluminum and duralumin. When marking blanks from these materials, scrippers are not used, since when drawing the protective layer, the protective layer is destroyed and conditions are created for the appearance of corrosion. Marriage with markup, i.e. the mismatch of the dimensions of the marked workpiece with the drawing data occurs due to inattention of the scribe or inaccuracy of the scribe tool, dirty surface of the plate or workpiece.

Chopping metal.

Metal cutting  - this is an operation in which excess metal layers are removed from the surface of a workpiece or the workpiece is cut into pieces. Cutting is carried out using a cutting and percussion instrument. When cutting, a chisel, crosshead and a groove serve as a cutting tool. The percussion instrument is a bench hammer. Purpose of cutting: - removal of large irregularities from the workpiece, removal of hard crust, scale; - cutting of keyways and lubrication grooves; - cutting the edges of cracks in the parts for welding; - cutting down of rivet heads when removing them; - cutting holes in the sheet material. - cutting of bar, strip or sheet material. Chopping can be fine and rough. In the first case, a chisel removes a layer of metal with a thickness of 0.5 mm in one pass, in the second - up to 2 mm. The machining accuracy achieved by cutting is 0.4 mm.

Editing and straightening.

Editing and straightening  - operations to straighten the metal, workpieces and parts with dents, waviness, curvature and other defects. Editing can be done manually on a straight steel plate or cast-iron anvil and machine on the right rollers, presses and special devices. Manual editing is used when processing small batches of parts. The enterprises use machine editing.

Bending.

Bending - operation, as a result of which the workpiece takes the required shape and dimensions due to the extension of the outer layers of the metal and compression of the inner. Bending is performed manually with hammers with soft strikers on a bending plate or using special devices. Thin sheet metal is bent with mallet, wire products with a diameter of up to 3 mm - with pliers or round-nose pliers. Only plastic material is subjected to bending.

Cutting.

Cutting (cutting)  - separation of high-quality or sheet metal into parts using a hacksaw blade, scissors or other cutting tool. Cutting can be done with or without chip removal. When cutting metal with a hacksaw, hacksaw and turning-cutting machines remove chips. Cutting materials with manual lever and mechanical scissors, press scissors, nippers and pipe cutters is carried out without removing chips.

Dimensional processing.

Sawing metal.

Filing  - operation to remove a layer of material from the surface of the workpiece using a cutting tool manually or on filing machines. The main working tool for filing - files, files and rasps. Using files process flat and curved surfaces, grooves, grooves, holes of any shape. The accuracy of filing is up to 0.05 mm.

Hole machining

When processing holes, three types of operations are used: drilling, countersinking, reaming and their varieties: reaming, countersinking, counting. Drilling  - operation for the formation of through and blind holes in the solid material. It is carried out with the help of a cutting tool - a drill, performing rotational and translational movements about its axis. Purpose of drilling: - obtaining non-responsible holes with a low degree of accuracy and a roughness class of the processed surface (for example, for mounting bolts, rivets, studs, etc.); - obtaining holes for threading, deployment and countersinking.

Drilling  - increasing the size of the holes in the solid material obtained by casting, forging or stamping. If high quality of the processed surface is required, then the hole after drilling is additionally countersinked and deployed.

Countersinking - processing of cylindrical and conical pre-drilled holes in parts with a special cutting tool - a vertical drill. The purpose of countersinking is to increase the diameter, improve the quality of the processed surface, increase accuracy (reduce taper, ovality). Reaming can be the final hole machining operation or intermediate before the hole is deployed.

Countersinking  - this is processing with a special tool - countersink - of cylindrical or conical recesses and chamfers of drilled holes for the heads of bolts, screws and rivets. Counterblasting is performed by counterbores for cleaning end surfaces. Lugs process bosses for washers, thrust rings, nuts.

Deployment  - This is the finishing of the holes, providing the greatest accuracy and cleanliness of the surface. The holes are drilled with a special tool - reamers - on drilling and turning machines or manually.

Category: Plumbing work

Flat marking

Plane marking consists in drawing contour lines (marks) on a material or workpiece — parallel and perpendicular, circles, arcs, angles, various geometric shapes in given dimensions or outlines in patterns. Contour lines are applied as solid patterns. To preserve traces of scratches until the end of the treatment, often with the help of a punch, small indentations are used, which are closely spaced from each other, or a control risk is applied next to the marking risk. Risks should be subtle and clear.

The following tools are used to mark, measure and verify the correctness of the manufacture of products; ruler, square, compass, vernier caliper, caliper, caliper, scale and scale ruler, protractor, scriber, center punch, marking plate and templates.

In fig. 1 shows the simplest marking and measuring tools, as well as measurement methods.

Measurement accuracy with a millimeter scale ruler, caliper and caliper - 0.5 mm, vernier caliper - 0.1 mm. For correct marking, it is necessary that the tool is accurate and serviceable.

The correctness of the line is checked as follows. Draw a line along the ruler, shift the ruler to the other side of the line, without turning it over, combine the edge of the ruler with the drawn line, which in the correct ruler should coincide at all points with the drawn line.

The straightness of the sides of the square is checked with an accurate ruler. To check the correctness of the right angle, the square is applied on one side to the ruler, and a vertical line is drawn on the other side. Then the square is shifted to the other side of the drawn line so that its top remains at the same point. The square is applied close to the ruler and a second vertical line is drawn. If the square is correct, both lines should coincide.

The correctness of the applied divisions on a ruler or meter is checked as follows: the legs of the compass are placed 2-3 cm and rearranged along the entire length of the ruler or meter.

Fig. 1. A marking and measuring tool and measurement techniques: a - scale ruler; b - measuring methods with a scale ruler; c - plumbing square and methods for checking the correctness of the angle; d - caliper and methods for measuring them; 1.9 - fixed and movable jaws for external measurement, 2.4 - jaws for internal measurement, 3 - internal dimension of the part, 5 - screw for fixing the frame, 6 - movable frame, 7 - rod with millimeter division, 8 - nonius, 10 - outer dimension of the part, 11 - depth gauge; d - caliper and caliper and methods for measuring them; f - a straightedge and methods for checking its machined surface

The steel scriber should be pointed, round cross-section, so as not to spoil the ruler and square. When drawing, the scriber should be pressed firmly to the edge of the ruler or square, tilting it slightly forward. A clear thin risk should remain on the steel sheet. Brass scriber leaves a clearly visible mark on black steel.

The legs of the marking compass should be pointed and hardened.

When marking thin sheet steel, one drawing leg should be sharpened sharply, and the other should have a slightly oblique point, so as not to leave holes in the sheet steel.

When drawing circles on metal, centers are marked with a center punch.

Methods of plane marking on metal are shown in Fig. 2. Parallel lines are drawn with a scriber along a square (Fig. 2, a, b).

Fig. 2. Methods of plane marking a - drawing, b - scribing along the square with a parade of "distinct lines, c - drawing with a scribe across a square perpendicular" to the line, d - building a perpendicular line using a compass, e - building parallel lines using a compass, e - construction of a hexagon inscribed in a circle, g - construction of corners by a protractor, 3 - division of angles using a compass

Perpendicular lines are built using a square with one right angle.

You can lower the perpendicular from point O to the straight line AB or restore the perpendicular to the straight line from point M using a ruler and a square (Fig. 2, c). The ruler is aligned with the AB line, the square is firmly placed on one side of the ruler and moved along the ruler until the other side of the square is aligned with point O or M, and then a line is drawn perpendicular to the AB line.

The perpendicular can also be restored and lowered with a compass (Fig. 2, d). Two points are made from a point M on a straight line with an arbitrary radius (short arcs) 1 and 2. Then, from points 1 and 2 with a radius larger than segment 1-2, serifs 3 and 4 are made. The intersection point S of serifs S and 4 is connected to point M. The resulting EM line will be perpendicular to the AB line.

Parallel lines can be built using a square and a compass. To draw the SH line (Fig. 2, e), parallel to the AB line, from any two points of the AB line, for example D and G, restore perpendicular lines using a square or compass, on which equal segments (in our case 6 cm) are laid DE and ZhZ. Through points E and 3, a VG line is drawn, which will be parallel to the AB line.

Parallel lines can also be drawn using a ruler and a square. If you move the square along the ruler, then all the lines drawn along the side of the square will be parallel to each other.

The marking of the circle on the metal is carried out using a compass, having previously drawn the center О as a center punch (Fig. 2, f).

The distance laid by the compass from the center O to any point on the circle is called the radius and is denoted by the letter R.

When marking, it is often required to divide the circle into equal parts, as well as measure, build and divide the angles. To divide the circle into two equal parts, it is enough to draw a diameter. To divide it into 4, 8, 16, 32 parts, first two mutually perpendicular diameters are carried out, which divide the circle into four equal parts. Then each part is divided in half, etc., and 8, 16, and 32 parts are obtained. To divide the circle into 3, 6, 12, 24 parts, etc., its radius is laid on the circle, which fits exactly six times. Connecting these points through one, divide the circle into three parts. Dividing the ‘/ b part of the circle in half and into four parts, get its parts Vi2 and V24.

Angles are measured by a protractor (Fig. 2, g). Using a protractor, the construction of corners is most simple and correct.

Angles of 90, 45, 60, 120 and 135 ° can also be constructed using a square, compass and ruler. An angle of 90 ° is built using a square and a ruler. An angle of 45 ° can be built by dividing the angle of 90 ° in half. To do this, an arc 1 is drawn from the vertex of angle A (Fig. 2, h) with an arbitrary radius, intersecting the sides of the corner at points B and D and the continuation of the side of the AG at point B. From points B and D, the same radius is used for notches 2 and 3 intersecting at point D. The line connecting point D with the vertex of angle A divides the angle in half.

Having drawn an angle of 45 ° to an angle of 90 °, an angle of 135 ° is obtained.

To build angles of 30 and 60 °, you need to divide the right angle into three parts. One third of the right angle will be 30 °, and two thirds will be 60 °.

To divide a right angle into three parts, an arc is drawn from the vertex of angle A (Fig. 2, h), intersecting the sides of the angle at points B and C. From these points, the same radius is made on the arc of notches 4 and 5. The resulting points E and G connect with the top of the angle A. The lines EA and JA divide the angle into three equal parts.
  Various geometric figures are applied to the plane with the same marking tool: a ruler, a square, a pair of compasses and a protractor.
  To speed up and simplify the planar layout of identical products, sheet metal templates are used.

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

Large parts are marked on the stove, and small parts are in a vice.

If the product is hollow (for example, a flange), then a wooden cork is hammered into the hole and a metal plate is fixed in the center of the cork, on which the center for the compass leg is marked with a punch. The flange is marked as follows. The surface of the workpiece is painted with chalk, outline the center and draw a circle with a pair of compasses: 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 the template, and the holes are drilled along the conductor without marking.

It is necessary to lay out accurately and carefully, since the quality of the product depends on the correct marking.

Marking tools must be stored in designated areas.

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Training and Production Center

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Locksmith

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production training

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Purpose and technical requirements of marking

Marking is the operation of applying to the surface of a part or a blank of marking patterns that define the contours of the part profile and the places to be processed. The main purpose of marking is to indicate the boundaries to which the workpiece must be processed. To save time, simple blanks are often machined without preliminary marking. For example, in order for a fitter-toolmaker to make an ordinary key with flat ends, it is enough to chop off a piece of square steel from a bar of a certain size, and then file it in the sizes indicated on the drawing.

Spatial marking   - this is the marking of the surfaces of the workpiece (part) located in different planes and at different angles, performed from any initial surface or marking risks selected for the base.

Spatial marking is most common in mechanical engineering; in receptions, it differs significantly from planar. The difficulty of spatial marking lies in the fact that it is necessary not only to mark separate surfaces of the part located in different planes and at different angles to each other, but to link the markings of these separate surfaces to each other.

Figure 1. Spatial marking

Three main marking groups are used: machine building, boiler room and ship. Engineering marking is the most common locksmith operation.

The most common tool for measuring linear dimensions is a meter - a metal ruler on which a scale is applied with divisions expressed in millimeters. The scale mark of the ruler is 1 mm.

Fig.2 . Shrinking 1% meter versus main ordinary meter

Spatial marking  significantly different from planar. The difficulty of spatial marking lies in the fact that the turner does not just have to mark separate surfaces of the part located in different planes and at different angles to each other, but also to link the markings of these surfaces to each other

When marking, various measuring and special marking tools are used. To improve the visibility of the marking lines, a series of shallow points should be knocked out on them with a punch at a small distance from each other. Marking is most often done on special cast-iron marking plates.

In the serial production of parts, it is much more profitable to use instead of individual marking copying.

Copy(outline) - drawing on the workpiece of shape and size according to the template or the finished part.

The copy operation is as follows:

a template or finished part is superimposed on a sheet of material;

the template is fastened to the sheet using clamps;

outlines of the template are outlined.

to improve line visibility

Templates are made according to sketches, taking into account all types of allowances. The material for the templates can be sheet steel, sheet metal, cardboard. The method of arrangement of the workpieces of parts on the material is called will reveal.

There are three main ways of cutting sheets:

Individual cutting, in which the material is cut into strips for the manufacture of parts of the same name (plates for stamping Raschig rings, strips for laying heat exchangers).

Mixed cutting, in which a set of parts is marked out on a sheet. Mixed cutting allows you to save metal, but this increases the complexity, as the number of operations and readjustments of equipment increases.

For mixed cutting, cutting cards are developed that represent sketches of the placement of parts on metal, drawn on a scale on a sheet of paper. Cutting cards are made in such a way as to place on the sheets the entire set of parts necessary for the manufacture of units and provide the most rational and convenient cutting of blanks. Figure 3.1.3 shows an example of cutting cards of a cyclone, from which it can be seen that the correct cutting provides straight-line cutting.

Figure 3 Cutting cards: a - correct cutting; b - irrational cutting

Marking tools, fixtures and materials

Scriber  they are the simplest tool for drawing the contour of a part on the surface of the workpiece and are a rod with a pointed end of the working part. Inkers are made of tool carbon steels of grades U10A and U12A in two versions: unilateral (Fig. 2.1, a, b) and bilateral (Fig. 2.1, c, d). Scrippers are made with a length of 10 ... 120 mm. The working part of the scriber is quenched at a length of 20 ... 30 mm to a hardness of HRC 58 ... 60 and is sharpened at an angle of 15 ... 20 °. Risks on the surface of the part are applied with a scriber, using a scale ruler, template or sample.

Reismas  used for applying pictures on the vertical plane of the workpiece (Fig. 2.2). It is a scriber 2, mounted on a vertical rack mounted on a massive base.

Marking compassesused for drawing arcs of circles and dividing segments and angles into equal parts (Fig. 2.3). Marking compasses are made in two versions: simple (Fig. 2.3, a), which allows you to fix the position of the legs after they are set to size, and spring (Fig. 2.3, b), used for more accurate size setting. For marking the contours of critical parts, use a marking caliper

In order for the marking risks to be clearly visible on the marked surface, point recesses are applied to them - cores, which are applied with a special tool - punch.

When marking, you should carefully handle pointed scrippers. To protect the hands of the worker before marking on the tip of the scriber, you must put on a cork, a wooden or plastic cover.

To install heavy parts on a screed plate, use hoists, hoists or cranes.

Oil or other liquid spilled on the floor or screed may cause an accident.

Bibliography

1. Makienko N.I.:, Plumbing with the basics of materials science. - M.: Higher School, 2004

2. Makienko N.I.: Practical work on plumbing. - M .: Higher school, 2001

3. Kropyvnytskyi N.N.: General course of plumbing. - L .: Mechanical engineering, 1997.

Marking lines are applied in the following order: first, horizontal, then vertical, then inclined, and last, circles, arcs, and curves. Drawing arcs in the last turn makes it possible to control the accuracy of the location of the direct images: if they are applied accurately, the arc will close them and the conjugations will turn out smooth.

Direct risks are caused by the scriber, which should be tilted away from the ruler (Fig. 45.6) and in the direction of movement of the scriber (Fig. 45, a). The inclination angles must correspond to those indicated in the figure and do not change during the drawing process, otherwise the risks will not be parallel to the ruler. The scriber is always pressed to the ruler, which should fit snugly against the part.

Risks lead only once. When the lines are drawn again, it is impossible to get into exactly the same Mestre; as a result, several parallel patterns are obtained. If the risk is applied poorly, it is painted over, allowed to dry and carried out again.

Perpendicular lines (not in geometric constructions) are applied using a square. The part (blank) is placed in the corner of the plate and lightly pressed with a load so that it does not move during the marking process. The first risk is carried out on a square, the shelf of which is applied to the side surface b (Fig. 46, a) of the scribe (position of the square 1-1). After that, the square is applied with a shelf to the side surface a (position // - ID and spend the second risk, which will be perpendicular to the first.

Parallel risks (lines) are applied using a square (Fig. 46.6), moving it to the desired distance.

The search for circle centers is carried out with the help of center finders and center detectors. The simplest center finder (Fig. 47, a) represents a square with a ruler attached to it, which is a bisector of a right angle. Installing a square-center finder on the outer surface of the product, draw a straight scriber. She will go through the center of the circle. Turning the square at a certain angle (about 90 °), draw a second straight line. At their intersection is the desired center.

With a small diameter of the marked end, the center finders are inconvenient to use. In this case, use a center punch.

A center-center punch (Fig. 47.6) is used to apply centers on cylindrical parts with a diameter of up to 40 mm. It has an ordinary punch 7, placed in a funnel (bell) 3. A flange 2 is inserted into the funnel with a hole in which the punch easily slides. The marking consists in the fact that the funnel is pressed to the end of the product and with a hammer hit the head 5 of the center punch. Under the action of the spring 4, the punch is always in the upper position.

Articulated price finder K. f. The hook (Fig. 47, c) has advantages over other center finders. With it, the position of the center lines is found not only

cylindrical, but also conical, rectangular and other holes. The center finder has four pivotally interconnected strips connected by springs. When the center finder is operating, the springs press the ends of the bars to the walls of the hole. Points A and B plotted on the axis of the hinges indicate the position of mutually perpendicular lines.

Marking of angles and slopes is carried out using transport (Fig. 48, a) and goniometers. When marking, the protractor (Fig. 48.6) is set to a predetermined angle, holding its base with the left hand, and with the right hand, turning the wide end of the ruler until the end of the ruler, in the form of an arrow, coincides with the division of the specified degrees plotted based. After that, the ruler is fixed with a hinge screw, then lines are drawn with a scriber.

Pocket vernier caliper  (Fig. 49) with a ruler for measuring the depth of production of the GDR, instead of the usual vernier, it has a dial indicator. This tool is successfully used by markers, as it reduces the voltage of vision when taking samples and provides sufficient accuracy. The scale of the indicator dial is 1/10 mm, the measurement limit is 135 mm, the working surfaces of the jaws are hardened along the entire length.

  Centerfinder Protractor(Fig. 50) differs from the usual protractor-centric detector by the presence of a protractor 2, which, using the engine 4, can be moved along the ruler 3 and fixed on it in the desired position by a nut 5. The ruler is attached to the square 7. The protractor makes it possible to find the centers of the holes located on a given distance from the center of the cylindrical part and at any angle. In fig. 50, the position of point d is found, which is at an angle of 45 ° and at a distance of 25 mm from the center.

The spirit level with a degree scale and a dial type goniometer (Fig. 51), produced in the GDR, can be used for marking operations. The spirit level (Fig. 51, a) is rational to use when measuring slopes with an accuracy of 0.0015 ° and when installing parts on a slab in cases where the plane of the marking slab is strictly level-adjusted.

The dial gauge (Fig. 51, 6) does not require a lot of visual stress when setting angular values ​​on a scale.

The price of the division of the dial is 5 arc minutes. A full turn of the arrow corresponds to a change in the angle between the rulers by 10 °. In the round hole of the dial, the number corresponding to an integer number of degrees is counted. The auxiliary leg is used to measure small angles.