RU2271902C2 - Method for making teeth of hack saw webs - Google Patents

Abstract

FIELD: machine engineering, possibly tool production, for example working of teeth of hack saw webs.

SUBSTANCE: method comprises steps of assembling blanks of hack saws in pack and placing separation plates between them; arranging assembled pack on working table of machine tool with use of holder and forming teeth at moving working table; shaping teeth by means of chisel subjected to vertical reciprocation motion from rotating cam shaft. Metal of blank is cut by means of blade of chisel and simultaneously it is plastically deformed by means of face of chisel while uniformly moving working table in lengthwise direction depending upon revolution number of cam shaft and providing non-uniform reciprocation motion of chisel. Speed of said non-uniform motion of chisel is determined according to desired profile of teeth in longitudinal cross section.

EFFECT: enhanced efficiency, improved quality and enlarged assortment of products.

3 cl, 3 dwg

Description

The invention relates to mechanical engineering and can be used, for example, in tool production when processing cutting teeth of hacksaw blades.

A known method [1] of the manufacture of teeth on band tools, in which the blanks are collected in a bag, secured in a machine tool and with a special mill, the teeth are milled to a full depth equal to the height of the teeth of the blade, see Ushakov MV, Simakin F.A. Determination of optimal processing conditions for small periodic profiles with milling cutters with helical tooth backing. Bulletin of Tula State University, series "Engineering", Issue 3, Part 1, Tula: TulSU, 1997, p. 171.

The disadvantages of the known method of manufacturing teeth on band tools are: the complexity of the design of the tool used, significant cutting forces (~ 6000 N), due mainly to the width of the machined surface (from 300 to 310 mm).

The closest technical solution is the method [2] for obtaining the teeth of hacksaw blades by grinding, in which the workpieces of hacksaw blades are pre-assembled into a bag, dividing plates are placed between them, mounted on the machine’s work table and the teeth are formed when the work table is moved (RU 2089357 C1, 10.09. 1997, B 21 D 63/12).

The disadvantages of the closest method are: low productivity and quality, as well as a narrow range of manufactured products.

The technical result of the invention is to increase productivity, quality and expand the assortment of manufactured products with a given tooth profile on the workpieces in the form of a tape (plate) or any other shape.

The expansion of the functionality of the notching method when receiving the teeth of hacksaw blades of a given geometry is achieved:

1. Pre-assembly of hacksaw blade blanks in a package with the location of separation plates between them, installation using the clip of the resulting package on the machine’s work table and the formation of teeth when moving the work table and chisel. The chisel is informed of the vertical reciprocating movement from the rotating cam shaft from the condition of ensuring the cutting of the workpiece metal with the chisel blade and simultaneous plastic deformation of the workpiece metal by its face with uniform longitudinal movement of the working table, which is set depending on the speed of the cam shaft.

2. The formation of the teeth with the specified values of the front and rear angles of the cutting wedge of the tooth of the blade.

3. The choice of speed of the reciprocating movement of the chisel, depending on the desired profile of the back and the front surface of the teeth.

The invention is illustrated by drawings, in which Fig. 1 shows a kinematic diagram of a notching machine, Fig. 2 shows the fastening of blanks during cutting, Fig. 3 shows a diagram of the formation of a profile with a chisel in the section - (back surface), and in the section - (front surface ) in the longitudinal section of the teeth of the blade.

A device for manufacturing the teeth of hacksaw blades by the method of notching (Fig. 1) contains a chisel 1 fixed in the cartridge 2 of the percussion mechanism 3. The chisel 1 is mounted at an angle to the surface of the working table 4, on which a clip 5 with blanks 6 is fixed, for example, in the form of canvases .

In the clip 5 of the workpiece 6 are located, alternating with the dividing plates 7, forming a package (figure 2). The desktop 4 has the ability to longitudinally move relative to the fixed table 8 of the cutting machine. The package of blanks is pressed by the presser foot 9 to the clip 5 with blanks with a force of R _l . The hammer 10 (figure 1) is installed in contact with the protrusion of the cam shaft 11, which is connected to the electric motor 14 through the driven pulley 12 and the belt drive 13, and connected to the driven pulley 19 through the belt drive 17 with the tension pulley 19. The pulley 19 is fixed to the worm the shaft 20, which is engaged with the worm wheel 21. The worm wheel is mounted on the lead screw 22.

The running sleeve 23 is connected to the housing of the working table 4, with which the rod 24 of the pneumatic cylinder 25 is also connected.

The working spring 26 is in constant contact with the tensioning mechanism 27, which is mounted on the column 28. The discharge spring 29 and the loading spring 30 are connected to the column 28 and the table 8.

A method of manufacturing the teeth of hacksaw blades is as follows. Pre-assemble the clip 5 from the blanks of hacksaw blades 6, between which set the separation plate 7 (figure 2).

The clip is fixed in the desktop 4, which is installed on the table 8 of the cutting machine. Then they press vertically the hacksaw blanks with the presser foot 9, and the side surface of the holder with the wedge 31 using the bolt 32 (Fig. 2).

In the process of manufacturing the teeth of hacksaw blades due to the directed deformation of the metal of the workpieces 6 form the geometry of the teeth of the blade.

The hammer 10 (FIG. 1) periodically comes into contact with the protrusion of the cam shaft 11, which receives rotation from the electric motor 14 through the V-belt drive 13. The rotation of the cam shaft 11 is kinematically connected through the flat-belt gear 17 and the worm pair 20-21 with the lead screw 22 and the lead sleeve 23.

When the percussion mechanism 3 is raised by the protrusion of the cam shaft 11, the percussion mechanism compresses the working spring 26, which, after the cam shaft exits from under the hammer, gives its energy to the percussion mechanism with a chisel 1.

The formation of the surface profile of the teeth (figure 3) is carried out in the following sequence. Chisel 1 is moved along line I-II. From point I to point II, the workpiece metal is cut with a chisel blade (point "a"). On the line I-II form the back (back surface) of the tooth profile. At the same time, the surface E of the chisel 1 plastically deforms the metal of the workpiece 6. The metal is forced up and onto the side faces of the workpiece. The deformation in the lower part of the tooth base is completed and the front surface of the tooth is formed along the line II-III. As a result of plastic deformation, the tooth peaks at point III exceed the surface of the workpiece 6, and thickenings are formed on the side faces of the workpiece (positions B ₁ ; C; D ₃ ).

The uniform longitudinal movement of the workpiece with a speed of V ₁ , which is set depending on the speed of the cam shaft, depends on the pitch of the teeth of the blade. The uneven reciprocating movement of the chisel with a speed of V ₂ is determined depending on the desired tooth profile in the longitudinal section and set by the cam shaft profile.

, а перемещение зубила 1 при проникновении в тело заготовки 6 задают в виде изменения (перепада) величины радиуса-вектора Δr кулачкового вала для каждой координаты Y, гдеThe depth of penetration of the chisel depends on the profile of the teeth of the blade between points I and II, which is set by the profile of the cam shaft 11, therefore, the speed V _{2 is} uneven. For example, when choosing a part of the section between points I and II, in the form of an arc of a circumscribed circle of radius R and passing through points I and II, the coordinates X and Y of the positions of point “a” are determined within the specified limits on the section I-II. Set the X coordinate of the point "a" in the interval X ₁ <X <X ₂ , determine the Y coordinate of the point "a", where

and the movement of the chisel 1 upon penetration into the body of the workpiece 6 is set in the form of a change (difference) in the radius vector Δr of the cam shaft for each coordinate Y, where

Δr = Y / cosα,

where Δr is the radius vector of the cam shaft profile,

ΔY is the coordinate of the point "a",

α is the angle of inclination of the axis of the chisel to the plane of the table.

The kinematic adjustment of the machine is carried out, observing the dependence: the longitudinal speed V ₁ should be equal to the tooth pitch with a cam shaft 1 with one protrusion and two steps with a cam shaft with two protrusions in one revolution. The front surface of the blade along the line II-III is formed when the chisel 1 is lifted up. Next, the cycle is repeated.

The method allows to make a hacksaw blade. Take a hacksaw blade 2800-0005 according to GOST 6645-86, the tooth profile is a right triangle, pitch t is 1 mm, the angle of inclination of the back (section I and II) of the teeth is α = 40 °, the cutting machine ZiR-6, the cam shaft with one protrusion , the angle of rotation of the cam shaft from 0 to 180 ° every 30 °, R = 2 mm

Calculation to obtain the specified teeth.

The length of the segment between points I and II of figure 3

t / cosα = 1 / cos40 ° = 1 / 0.766 = 1/3 mm.

The center of the circumscribed circle (point O) of radius R = 2 lies on the perpendicular to the center of the segment between points I and II.

The angle ω is determined by: cosω = t / 2Rcosα = 1/2 · 2cos40 ° = 0.325; ω = 71 °.

The angle φ is determined: φ = 180-ω-α = 69 °.

The coordinates of point I are determined relative to the center O of the circumscribed circle of radius R, X ₁ = const = R · cos69 ° = 0.717 mm, Y ₁ = const = R · sin69 ° = 1.867 mm, hereinafter, the numerical values of the quantities are rounded to thousandths of mm

The speed V _{1 is} determined: V ₁ = S _x · b = IP _x · b / 360 = 0.00278, where

P _x = S _x · b - moving the slide from the lead screw, mm,

I = 0.1662 - gear ratio of the cutting machine ZiR-6 with a tooth pitch of up to 1 mm,

P _x · b = 6 - lead screw pitch, mm.

The displacement S · b is determined when the cam shaft is rotated through an angle φ = 30 °, S _x · b = 0.083 mm.

The X coordinates of point "a" will be determined in the range X ₁ <X <X ₂ , where X ₁ = const = 0.717 mm, X ₂ = const = 1.217 mm.

The X coordinate is determined by turning the cam shaft φ from φ _to = 0 ° to φ _to = 30 ° X _{30 °} = 0.80 mm.

.The Y coordinate is determined by turning the cam shaft φ from φ _to = 0 ° to φ _to = 30 °,

.

The change in the radius vector Δr = ΔY / cosβ, where

ΔY = Y _{0 °} -Y _{30 °} = 0.034 mm; Δr = 0.0356 mm.

Similarly, calculations are performed for the rotation angles of the cam shaft of 60 °, 90 °, 120 °, 150 °, 180 °.

Analysis of the calculation data shows that the speed V _{1 is} uniform, and V _{2 is} uneven.

The invention improves the productivity, quality and expand the range of manufactured products with a given profile of the teeth of hacksaw blades in the form of a tape, plate or any other shape, which allows to expand the functionality of the method of obtaining teeth of hacksaw blades of a given geometry with different sharpening angles of the chisel.

Claims (3)

1. A method of manufacturing teeth of hacksaw blades, including pre-assembly of hacksaw blade blanks in a bag with the location of separation plates between them, installing the resulting package on the machine’s work table and forming teeth when moving the work table, characterized in that the installation of a package of hacksaw blade blanks on the desktop produced using a clip, while the package of blanks is pressed against the clip, the formation of teeth of hacksaw blades is carried out with a chisel, which informs the vertical return the reciprocating movement from the rotating cam shaft from the condition of ensuring the cutting of the workpiece metal with a chisel blade and simultaneous plastic deformation of the workpiece metal by its face, while uniformly moving the working table, which is set depending on the speed of the cam shaft, and uneven reciprocating motion chisels, the speed of which is determined depending on the desired tooth profile in longitudinal section. 2. The method according to claim 1, characterized in that the teeth are formed with predetermined values of the front and rear angles of the cutting wedge. 3. The method according to claim 1 or 2, characterized in that the speed of the reciprocating movement of the chisel is determined depending on the desired profile of the back and the front surface of the teeth.

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