RU2063829C1 - Method of holes conditioning in hard material - Google Patents

Abstract

FIELD: metals working by pressure, production of precision holes and also outer contours with facet in hard material blanks. SUBSTANCE: method provides for putting fin, that is formed during initial conditioning of hole, into such volumetric form, that during final removal of rest stock along near edge zone with fin, provides additional amount of material breaking-off. Method of hole conditioning in hard material provides for piercing of preliminary hole, initial conditioning of near edge zone of preliminary hole on part of blank thickness with leading fin inside hole and beyond lower surface of blank, final removal of stock along near edge zone on rest part of blank thickness with fin by its breaking-off by punch, that passes smoothly through conditioned area. EFFECT: improved process. 2 cl, 3 dwg

Description

 The invention relates to the processing of metals by pressure and can be used to obtain holes and external contours with a chamfer in parts of solid sheet materials with high surface finish.

 A known method of producing holes with chamfer in sheet material, including punching holes and extruding chamfers / "Technology of cold stamping" A.N. Malov, Mechanical Engineering, M, 19691. p.379, Fig. 211 /.

 The disadvantage of this method of producing holes with a bevel is the swelling of the surface and distortion of the edges of the workpiece due to extrusion of the material during the formation of the bevel.

 There is a method of producing holes with a clean surface in a sheet material in which a preliminary hole is punched, then the surrounding brilliant belt obtained by punching is pushed out of the zone into the annular section adjacent to the chip surface, such a volume of material that is necessary to fill the annular section in the chip zone , and then calibrate the hole (A.S. and 1412842, 21 D 28/10, publ. 1988 g).

 Closest to the claimed method of stripping, the prototype is a method of stripping holes, including punching a preliminary hole, initial cleaning of the edge zone of the preliminary hole on the part of the thickness of the workpiece with the removal of the burr into the hole and the final removal of the allowance along the edge zone on the remaining part of the thickness of the workpiece with a punch freely passing through the cleaned area of the hole, and the matrix / A.s. N 1433566, B 21 D 28/16, decl. 01/28/87, publ. 10.30.88 g. N 40 /.

 The disadvantage of this method of stripping is the need to form a chamfer by extruding the material, which leads to bloating and distortion of the edges of the workpiece.

 The claimed method of stripping ensures the manufacture of precision bored holes in the blanks of solid material.

 This goal is achieved by the fact that in the method of stripping holes, including punching the preliminary hole, the initial cleaning of the edge zone of the preliminary hole on the part of the thickness of the workpiece with the removal of the burr into the hole and the final removal of the allowance along the edge zone on the remaining part of the thickness of the workpiece with a punch freely passing through the cleaned area holes, and the matrix, in addition, the initial cleaning is performed with the removal of part of the flap for the lower surface of the workpiece, and the final The pressure of the remaining allowance on the marginal zone sweeps produce its cleavage direction in which the cross-sectional plane of the workpiece passes through the connecting angle formed by the intersection of the upper surface of the remainder of the machining allowance of the marginal zone and buffed surface portion of the preliminary hole, and the leading edge of the matrix.

 The essence of the invention is to give the area formed during the initial cleaning of the hole, such a three-dimensional shape, which, when the final removal of the remaining allowance along the edge zone from the area provides cleaving an additional amount of material.

 The presence of the specified set of features of the claimed invention provides an increase in the quality of chamfered holes made due to the complete removal of the allowance along the edge zone left for stripping the hole, as well as the formation of a chamfer on one side of the workpiece by removing material, which eliminates swelling of the surface and distortion of the edges of the workpiece.

 In FIG. 1 shows the technological process of stripping holes using the claimed method of stripping holes: FIG. 1a punching a preliminary hole; FIG. 1b, the initial stripping on a part of the thickness of the workpiece with the formation of a bulk flake; FIG. 1c, the final removal of the allowance along the marginal zone on the remaining part of the workpiece thickness.

 In FIG. 2 shows a part obtained by manufacturing a hole using the inventive method for stripping a hole.

 In FIG. Figure 3 shows the initial stripping on a part of the thickness of the workpiece with the caulking of a bulk flake on a “hard” ejector.

 A method for cleaning holes in a solid material is as follows, FIG. 1.

The blank 1 is mounted on the matrix 2 and pressed with a clamp 3, FIG. 1a. The punch 4 is introduced into the material of the workpiece 1 and the cutting of the preliminary hole is performed. Waste 5 falls into a working window of the matrix 6. Thus the preform 1 made a preliminary hole with a diameter d _before with a rough surface. The value of d _pre is selected as well as with the known methods of stripping to obtain a protected hole with a diameter of d _nom . Then, the preform 7 with a punched preliminary hole 8 is mounted on a matrix 9 having a working one 10, conjugated with a punch 11, and pressed by a clamp 12, FIG. 1b. The punch 11 produce the initial cleaning of the preliminary holes and to a depth of h ₁ , moreover:
h ₁ <H / 1 /
where H is the thickness of the workpiece. The material cut off by the punch 11 of the allowance along the marginal zone of the preliminary hole 8 is crushed into the bulk flange 13, which is held on the jumper 14 with a thickness of h ₂ equal to:
h ₂ H h _1/2 /
moreover, the bulk flap 13 is located both inside the preliminary hole 8 and in the working window 10 of the matrix 9 below the lower surface 15 of the workpiece 7. The size of the jumper h ₂ is set based on the size of the chamfer to be obtained.

Then, the workpiece 17 with the preliminary hole 18 having the stripped part 19 is mounted on a matrix 20 having a working window 21, which has a diameter d _m corresponding to the outer diameter of the chamfer that needs to be trained and pressed with a clamp 22, FIG. 1c. The punch 23 has a diameter dp, and:
d _p ≅ d _nom -2Δ (3))
where d _{nom is the} nominal diameter of the manufactured hole and, accordingly, the diameter of the cleaned part 19 of the preliminary hole 18;
Δ minimum unilateral tolerance required for free passage of the punch 23 through the stripped portion 19 of the preliminary holes 18.

Thus, the punch 23 freely passes through the stripped part 19 of the pre-hole 18. The punch 23 makes chipping the remaining part 24 of the allowance along the edge zone and the volume region 25 held thereon. Volume region 25 has sufficient rigidity since solid material is processed and region 25 is not flat , but has a considerable thickness, so that, taking into account the thickness h _{2 of the} jumper 24, the chip occurs in the direction that in the plane of the cross section of the workpiece passes along the line connecting the angle formed by the intersection of the upper surface of the remaining part of the allowance along the edge zone and the surface of the cleaned preliminary hole, and the working edge of the matrix 20. The resulting waste falls through the working window 21 of the matrix 20.

Для придания поверхности фаски более высокой чистоты может производится дополнительное подчеканивание поверхности фаски на последующих операциях изготовления детали. При этом вздутия поверхностей и искажения краев заготовки не происходит, так как производится пластическая деформация только микронеровностей, образовавшихся при сколе материала.Thus, in the blank 30 of thickness H, a smoothed hole 31 of diameter d _nom and depth h _{1 is} obtained with a high surface quality and a chamfer 32 of size h2 by l, FIG. 2 where

To impart a higher purity to the chamfer surface, additional pinching of the chamfer surface can be carried out in subsequent manufacturing operations of the part. In this case, the swelling of the surfaces and distortion of the edges of the workpiece does not occur, since plastic deformation is carried out only microroughness formed during cleavage of the material.

 This method can be used to clean the external contours of the workpiece.

 To impart greater rigidity to the volume envelope, the initial stripping can be done by tapping the volume envelope on a “hard” ejector.

In this case, the initial cleaning is performed as follows in FIG. 3. A blank 35 with a punched preliminary hole 36 is mounted on a matrix 37 having a working window 38, conjugated with a punch 39, in which a pusher 40 is mounted, spring loaded with a force F _prot , and pressed with a clamp 41. An initial stripping of the preliminary punch with a force F holes 36 to a depth of h ₁ . The material of the allowance cut by the punch 39 along the marginal zone of the preliminary hole 36 is crushed into the bulk envelope 42, and the punch 39 also has to overcome the backpressure force F _prot created by the ejector 40. The force F _prot is set so that a dense bulk envelope 42 is formed, which is located inside the preliminary hole 36, and in the working window 38 of the matrix 37 below the lower surface 43 of the workpiece 35. The denser structure of the bulk flake 42 provides greater rigidity, since it is cut off at the initial cleaning, the allowance along the edge zone must first be compressed in the vertical direction and only after that the material will move horizontally inside the pre-hole 36. Accordingly, the high stiffness of the volume flap 42 allows for the final removal of the remaining part of the allowance along the edge area of the preliminary hole to chip more workpiece material and, accordingly, get a large bevel.

 The technical and economic effect of the use of the claimed invention is to reduce the cost of manufacturing precision holes in parts of solid material, which on one side must be chamfered, by making such holes on the dies simultaneously with the manufacture of the part itself. YYY2

Claims (2)

 1. A method of stripping holes in a solid material, including punching a preliminary hole, initial cleaning of the marginal zone of the preliminary hole to part of the thickness of the workpiece with the removal of burrs inside the hole and the final removal of the allowance along the edge zone on the remaining part of the thickness of the workpiece with a punch freely passing through the cleaned portion of the hole, and a matrix, characterized in that the initial cleaning is carried out with the removal of part of the flash over the bottom surface of the workpiece, and the final removal of the remainder shegosya allowance on the marginal zone shearing burr produce it, the direction in which the cross-sectional plane of the workpiece passes through the connecting angle formed by the intersection of the upper surface of the remainder of the machining allowance of the marginal zone and buffed surface portion of the preliminary hole, and the leading edge of the matrix.  2. The method according to p. 1, characterized in that the initial cleaning of the hole is performed with the pinning of the flake on the ejector.

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