2.5. Markup

3. Marking To obtain high-quality workpieces, you need to select the required amount of lumber (boards, bars) so that when cutting into workpieces, the minimum amount of waste is obtained. In building structures of buildings and structures used

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.

Billets are processed in the form of castings (obtained from metal poured into pre-prepared forms - earthen, metal, etc.), forgings (obtained by forging or stamping), or in the form of rolling material - sheets, rods, etc. d. (obtained by passing metal between rollers rotating in different directions, having a profile corresponding to the rolled product). If there are holes in the blanks, then a wooden or aluminum plate is tightly hammered into the hole to mark their centers

In the manufacture of the part, the dimensions are laid off exactly according to the drawing on the workpiece and marked with lines (risks) that indicate the boundaries of the processing to which the metal layer should be removed. Marking is used mainly in single and small-scale production. In factories of large-scale and mass production, the need for marking disappears due to the use of special devices-conductors, stops, etc.

Three main marking groups are used: machine building, boiler room and ship. Engineering marking is the most common locksmith operation. Boiler room and ship markings have some features. Depending on the shape of the marked blanks and parts, the markup is planar and spatial (volume).

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. In spatial marking, marking lines are applied in several planes or on several surfaces.

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. The degree of accuracy of the marking ranges from 0.25-0.5 mm. Errors in marking lead to marriage.

At machine-building and instrument-making factories, marking is carried out by workers with qualifications of scribers, but often this operation has to be performed by a toolmaker.

At the workplace of the scribbler or locksmith / toolmaker, there must be a variety of marking, control and marking tools and devices. One of such devices is an accurate control and marking plate, on which parts are installed and all devices and tools are prepared.

Marking plates are cast from gray fine-grained cast iron, in the lower part of the plate there are stiffeners that protect the plate from possible deflection. The upper, working surface and sides of the plate are precisely processed on planing machines and scraped. On the working surface of large plates, longitudinal and transverse grooves are sometimes made with a depth of 2-3 mm, a width of 1-2 mm at equal distances (200-250 mm), forming equal squares. Grooves make it easy to mount various fixtures on the plate.

"The dimensions of the plate are chosen so that its width and length are 500 mm larger than the dimensions of the workpiece to be marked.

Marking tools include: scriber (with one point, with a ring, double-sided with a curved end), marker (there are several types of them), marking compasses, center punches (regular, automatic, for stencil, for a circle), calipers with a conical mandrel, a hammer , compass center, rectangle, marker with a prism. The marking devices include: a marking plate, a marking box, marking squares and bars, a stand, a surface gage with a scriber, a surface gage with a movable scale, a centering device, a dividing head and a universal marking grip, a rotary magnetic plate, double clamps, adjustable wedges, prisms screw supports.

Measuring tools for marking are: a ruler with divisions, a caliper, a surface gage with a movable scale, a caliper, a square, an angle meter, a caliper, a level, a control ruler for surfaces, a stylus and reference tiles.

The auxiliary materials for marking include: chalk, white paint (a mixture of chalk diluted in water with linseed oil and the addition of an anti-drying oil), red paint (a mixture of shellac with alcohol and dye), grease, washing and etching materials, wooden bars and reiki, a small tin plate for paints and a brush.

Marking is the operation of drawing marking lines on the workpiece that define the contours of the future part or place to be processed.
  Accuracy achieved with conventional marking methods is approximately 0.5 mm.

Flat  marking, usually performed on the surface of flat parts, on strip and sheet material, consists in drawing contour parallel and perpendicular lines (patterns), circles, arcs, angles, center lines, various geometric shapes according to given sizes or the contours of various holes according to the patterns .

Spatialmarking is the most common in mechanical engineering; and in receptions it differs from planar.

Devices for flat marking

To carry out the marking, marking plates, linings, rotary devices, jacks, etc. are used.

The parts to be marked are installed on the scribing plate and all devices and tools are placed. The marking plate is cast from fine-grained gray cast iron.

The size of the plate is chosen so that its width and length are 500 mm larger than the corresponding dimensions of the marked blank. The surface of the plate should always be dry and clean. After work, the stove is brushed, thoroughly wiped with a cloth, greased with oil to prevent corrosion and covered with a wooden shield.

Tools for flat marking

Scriber, caliper, punch, ruler, square, hammer, etc.

Scrippers are used to draw lines (marks) on the surface to be marked with a ruler, a square or a template. Scrippers are made of tool steel U10 or U12, sharpened on a cone at an angle of 15-20 0.

Kerner -metalwork tools used for applying recesses (cores) on pre-marked lines.

Cores are made of tool carbon or alloy steel U7A, U8A, 7KhF or 8KhF, at an angle of 50-60 degrees.

  Compasses used for marking circles and arcs, dividing segments and circles, as well as for geometric constructions. Compasses are also used to transfer sizes from measuring lines to the part.

Reismas is the main tool for spatial marking and serves to draw parallel, vertical and horizontal lines, as well as to verify the installation of parts on the plate.

Preparing for the markup.

Before marking, do the following:

Clean the workpiece from dust, dirt, scale, corrosion, steel brush, etc .;

Thoroughly inspect the workpiece;

If shells, bubbles, cracks, etc. are detected, accurately measure them and, drawing up a layout plan, take measures to remove these defects during further processing (if possible);

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

Examine the drawing of the marked part, find out its features and purpose;

To specify the sizes;

Determine the base surface of the workpiece, from which dimensions should be set aside during the marking process;

In planar marking, the bases can be processed edges of the workpiece or center lines, which are applied first;

It is also convenient to take tides, bosses, and platikas for bases.

Marking Risks.  Marking risks are applied in the following order: first, horizontal, then vertical, then inclined, and last, circles, arcs, and curves.

Direct risks are caused by the scriber, which should be tilted in the direction of its movement and away from the ruler. The scriber is always pressed to the ruler, which should fit snugly against the part. Risks are carried out only once. If the risk is applied poorly, it is painted over, the dye is allowed to dry, and the risk is carried out again.
  The marking of angles and slopes is carried out using conveyors, calipers, goniometers.

Marking line marking.A core is a recess (hole) formed from the action of a punch when hit with a hammer. Punch centers should be located exactly on the marking lines.

Marking hammers.  For marking works use hammer No. 1 (weighing 200 g.).

Markup methods.Template marking 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 in this way.

Pencil markingit is produced in a line on blanks of aluminum and duralumin. It is not allowed to mark the latter with a scriber, since when drawing the protective layer, the protective layer is destroyed and traces of corrosion appear.

Defects:

Inconsistency of the dimensions of the marked workpiece with the drawing data due to inattention of the scribe or inaccuracy of the scribe;

Inaccuracy of setting the thicknesser to the desired size; the reason for this is the carelessness or inexperience of the scribe, the dirty surface of the plate or workpiece;

Careless installation of the workpiece on the plate as a result of the alignment of the plate.

Safety.

  Observe the following safety rules:

The installation of blanks (parts) on the stove and removing them from the stove must be done only in mittens;

Workpieces (parts) and fixtures must be installed securely closer to the middle;

Before installing workpieces (parts), check the plate for stability;

Check the reliability of the hammer mounting on the handle;

Only remove dust and scale from the screed plate with a brush, and with large plates with a broom.

Markup  called the operation of applying lines and points to a workpiece designed for processing. Lines and dots indicate processing boundaries.

There are two types of markup: flat and spatial.

Markup is called flatwhen lines and points are drawn on a plane, spatial  - when marking lines and points are applied to a geometric body of any configuration.

Spatial marking can be performed on a marking plate using a marking box, prisms and squares. In spatial marking, prisms are used to rotate the workpiece to be marked.

For flat and spatial marking, a drawing of the part and the workpiece for it, a marking plate, a marking tool and universal marking devices, a measuring tool and auxiliary materials are required.

Marking tools include: scriber (with one point, with a ring, double-sided with a curved end), marker (several types), marking compasses, center punches (ordinary, automatic for stencil, for a circle), calipers with a conical mandrel, a hammer, a center compass , rectangle, marker with a prism.

The marking devices include: a marking plate, a marking box, marking squares and bars, a stand, a surface gage with a scriber, a surface gage with a movable scale, a centering device, a dividing head and a universal marking grip, a rotary magnetic plate, double clamps, adjustable wedges, prisms screw supports.

Measuring tools for marking are: a ruler with divisions, a caliper, a surface gage with a movable scale, a caliper, a square, an angle meter, a caliper, a level, a control ruler for surfaces, a probe and reference tiles.

Auxiliary materials for marking include: chalk, white paint (a mixture of chalk diluted in water with linseed oil and the addition of an anti-drying oil), red paint (a mixture of shellac and alcohol with dye), grease, washing and etching materials, wooden bars and reiki, a small tin plate for paints and a brush.

Simple marking and measuring tools used in locksmith work are: a hammer, scriber, marker, ordinary punch, square, compass, marking plate, ruler with divisions, vernier caliper and caliper.

Flat or spatial marking of the part is carried out on the basis of the drawing.

Before marking, the workpiece must undergo mandatory training, which includes the following operations: cleaning the part from dirt and corrosion (do not produce on a marking plate); degreasing of the part (do not produce on a marking plate); inspection of the part in order to detect defects (cracks, shells, curvatures); verification of overall dimensions, as well as machining allowances; definition of a marking base; white coating of surfaces to be marked and drawing lines and dots on them; determination of the axis of symmetry.

If a hole is taken as a marking base, then a wooden cork should be inserted into it.

Marking base  - this is a specific point, an axis of symmetry or a plane, from which, as a rule, all dimensions on a part are measured.

Screwing up  called the operation of applying small points-recesses on the surface of the part. They define the centerlines and centers of the holes needed for processing, certain straight or curved lines on the product. The mounting is done in order to indicate on the part persistent and noticeable signs that define the base, the boundaries of processing or the place of drilling. The operation is performed using a scriber, center punch and hammer.

Marking using a template is used in the manufacture of a significant number of identical parts. A template made of sheet metal with a thickness of 0.5–2 mm (sometimes stiffened with a corner or a wooden battens) is superimposed on the flat surface of the part and is encircled by a scriber.

The accuracy of the applied contour on the part depends on the degree of accuracy of the template, the symmetry of the tip of the scriber, as well as on the way the tip of the scriber is moved (the tip should move perpendicular to the surface of the part). The template is a mirror image of the configuration of parts, lines and points that must be applied to the surface of the part.

The accuracy of the marking (the accuracy of transferring dimensions from the drawing to the part) depends on the degree of accuracy of the marking plate, accessories (squares and marking boxes), measuring tools, the tool used to transfer the dimensions, the degree of accuracy of the marking method, as well as the qualification of the marker. The accuracy of the marking is usually from 0.5 to 0.08 mm; when using standard tiles - from 0.05 to 0.02 mm.

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.

Purpose and types of marking.

The main purpose of marking is to indicate the boundaries to which the workpiece must be processed. Depending on the shape of the marked blanks for parts, the markup is divided into planar and spatial (volume).

Flat marking  It is performed on the surface of flat parts, on the surface of flat parts on strip or table material and consists in drawing contour and parallel perpendicular lines, circles, arcs, geometric shapes in zonal sizes or the contours of various holes on the workpiece.

For marking individual spatial details  located at different angles to each other in different planes and link the marking of these individual surfaces to each other.
Devices for flat marking are screed plates, pads, rotary devices, jacks. Tools for spatial marking scriber, farmers, compasses, marking bar - compass, ruler, squares.

Before marking, you must perform the following to clean the workpiece from dirt, corrosion, carefully inspect the workpiece to identify shells and cracks. To study the drawing and mentally place the layout plan, determine the base (surface) of the workpiece from which to postpone the dimensions to prepare the surface for painting. For staining, various compositions of chalk diluted in water, a solution of copper sulfate (CuSO4), alcohol varnish, and quick-drying varnishes, paints are used.
  To save time, simple blanks are often machined without preliminary marking.

For example, in order for a fitter-tool maker 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.

Billets are processed in the form of castings (obtained from metal poured into pre-prepared forms - earthen, metal, etc.), forgings (obtained by forging or stamping), or in the form of rolling material - sheets, rods, etc. (obtained by passing metal between rollers rotating in different directions, having a profile corresponding to the resulting hire),