RU2251466C2 - Progressive die set for punching, trimming and straightening forgings of box nut wrench - Google Patents

Abstract

FIELD: plastic working of metals, possibly operations for finish working of forgings of double-end box nut wrenches.

SUBSTANCE: die set includes upper and lower plates with guiding columns, punch for punching operation mounted on upper plate, stripper, lower die for punching, half-open trimming lower die and trimming punch. Trimming lower die is mounted on upper plate; it has cutting edge and cavity arranged behind collar of cutting edge and designed for freely placing forging of nut wrench. Trimming punch is mounted on lower plate and it has embracing supporting surface for fixing forging at trimming and straightening operations.

EFFECT: enhanced quality of forging.

9 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure, in particular to dies intended for finishing operations - punching holes in forgings, trimming burrs and straightening curvatures, and can be used for forging double-sided straight socket wrenches.

A serial stamp is known for trimming burrs and flashing holes in the forgings, containing upper and lower plates with guide columns, piercing and trimming punches fixed to the top plate, piercing and trimming dies with holes for failure and a piercing punch remover (Bryukhanov A.N., reference book “Forging and volumetric stamping of steel” under the editorship of MV Storozhev, volume 2, p. 282, fig. 23, ed. “Mechanical Engineering”, Moscow, 1968).

When applying the well-known stamp for finishing operations on forgings of double-sided straight socket wrenches obtained on horizontal forging machines (HCM), that is, for punching holes in the eyes of the wrench heads under the handle, as well as for trimming burrs, the following disadvantages were identified.

Firstly, when punching a hole in the eye of the key head, the forging is curved in the form of a slight bending of the head relative to the rod. The amount of curvature is influenced by the state of the cutting edges of the punch punch, as well as the gap between the die and the punch. The increase in the gap causes an increase in the degree of curvature of the forging, which may exceed the tolerance for alignment.

Secondly, the method of fixing the forgings on the edging matrix along the outer contour used for the forgings of the socket wrenches used in the known stamp does not always ensure the correct location of the forgings relative to the cutting edges and high-quality trimming. So, if the forgings are dimensioned in excess of the corresponding matrix size, that is, in cases where the body of the forgings is allowed to be “cut” when cutting the burrs, the lower surface of the burrs does not come into contact with the matrix surface when fixing the forgings and can be located at an angle to the latter. For forgings, this is expressed in a possible turn of the forgings relative to the longitudinal axis during its installation and fixation, which causes the appearance of defects in the form of incomplete trimming and crushing of burrs. After turning relative to the longitudinal axis and the bent key forging installed at the cutting position, the head and the rod are bent upwards, therefore, during the cutting process, the forging head and rod do not abut the supporting surface of the enclosing cavity of the cutting punch, but only along the lines of the initial touch, which leads to the local collapse of the shaft and the head The crushing of the edge of the head of the socket wrench causes a distortion of the geometric shape of the internal hexagonal cavity.

The technical problem to which the claimed invention is directed is to improve the quality of forgings of double-sided straight socket wrenches by eliminating the disadvantages inherent in the known serial stamp by changing its layout and design.

The problem is solved in that in a serial stamp for punching, trimming and straightening forgings of socket wrenches, containing the upper and lower plates with guide columns, a punch punch mounted on the top plate, a puller, a matrix for punching with a hole in the hole, a half-open cutting matrix with a cutting edge and a cutting punch with a covering surface, a semi-open cutting matrix is mounted on the upper plate and is made with a cavity located behind the cutting edge of the cutting edge for free placement of spanner wrenches, the cutter punch is fixed on the bottom plate, and its female surface is made supporting from the condition of fixing the forgings during cutting and dressing.

Common signs of the claimed invention and the known serial stamp for trimming burrs and flashing holes in the forgings are the presence in the stamp of the upper and lower plates with guide columns, a punch punch mounted on the upper plate, a puller, a die for punching with a hole in the hole, a half-open trim matrix with cutting edge and edging punch with female surface.

New features in the claimed invention are:

- a cut semi-open matrix is mounted on the upper plate and is made with a cavity located behind the belt of its cutting edge for free placement of the head of the forging of a wrench;

- the edged punch is fixed on the bottom plate, and its covering surface is made supporting from the condition of ensuring forging fixation during trimming and dressing.

The forging in the stamp according to the claimed invention, after punching the hole, is removed from the punching position and transferred to the cutting position of the burrs with the head bent up. The combination of new features of the claimed invention provides the following results. Firstly, in contrast to the known stamp, the forging during trimming of the burrs is fixed in the covering cavity of the edging punch, mounted on the bottom plate. The forging head is fixed both along the outer contour and by focusing on the plane of the eye. Additional fixation with the emphasis in the plane of the eye prevents the forgings from turning relative to the longitudinal axis and provides, in comparison with the known stamp, a more accurate setting of the forging at the cutting position. Secondly, fixing the edging matrix on the top plate eliminates the possibility of local crushing of the bent head and the forgings rod, since the half-open edging matrix has cavities for their placement during trimming and only comes into contact with the forging along the trimming contour. Thirdly, in comparison with the known stamp, when trimming the burrs, additional bending of the head of the forgings of the socket wrench is performed, that is, correction of the curvature of the forgings obtained by punching the hole is performed. Editing the bent head to the value of the permissible deviation from the alignment of the head and the rod is carried out in the covering cavity of the edging punch, which simultaneously plays the role of the straightening stream, by forcing the forgings with the edging matrix through the curved burrs located on the head along the forging axis on the sides of the curvature. The direction of editing the bend coincides with the direction of movement of the cut matrix. The dressing force is created by the force that occurs when trimming the burrs.

Elimination of the disadvantages of the known serial stamp used for finishing operations on the forgings of double-sided straight socket wrenches in this way can improve the quality of the forgings.

Figure 1 shows a sequential stamp for punching, trimming and dressing forgings socket wrenches, General view in section; figure 2 is a top view (with the top plate removed); figure 3 is a section bB in figure 1; figure 4 is a section bb in figure 3; figure 5 - forging of a double-sided straight socket wrench after stamping on the gas condensate field; figure 6 is a view of figure 5; Fig.7 is a section DD in Fig.5; on Fig - place E in Fig.6; figure 9 is a simplified diagram of the trimming of the burrs of forgings and edits.

The serial stamp for punching, trimming and straightening forgings of double-sided straight socket wrenches 1, having burrs 3 at the head 2, contains the upper 4 and lower 5 plates, interconnected by guide columns 6. The punch 7, mounted on the upper plate 4, and the matrix 8 are intended for punching a hole d under the handle in the eye of the head 2 of the socket wrench. To remove the forgings from the punch 7, a puller 9 is used. Matrix 8 has a hole for removing waste after punching, located above the hole in the bottom plate 5. A half-open matrix 10 with cutting edges for trimming burrs is attached to the top plate 4. The matrix has a cutting edge has a cavity 11 for free placement of the head 2 of the key after trimming the burrs. The trim punch 12, mounted on the bottom plate 5, at the same time serves to fix the forgings before cutting, which is carried out by means of the covering cavity of the end support surface of the punch. The figure of the enclosing cavity is performed by forging, taking into account the largest permissible values of the maximum deviations. The shift of the forgings in the horizontal plane is limited by the external female contour of the cavity of the punch, the possible turn of the forgings relative to the longitudinal axis is limited by the contact along the plane 13 of the eye between the punch and the forgings. The burrs 3 of the forgings 1 before trimming are located above the covering edges 14 of the punch and do not affect the accuracy of fixation.

The stamp works as follows. The forging of the socket wrench 1 is placed in the fixing cavity of the punch matrix 8 and, after being pressed by the stripper 9, punching the hole d with the punch punch 7. After punching, the forging receives a slight bend of the head 2 upward relative to the rod, and the bend line passes along the center line of the punch punch, i.e. centerline of the hole d. Further, from the punching position, the forging without rotation relative to the longitudinal axis is transferred and placed into the fixing cavity of the cutter punch 12. When the top plate 4 moves downward at the beginning of the cut, the cutoff matrix 10 is in contact with the curved burrs in those places that are located on the sides of the axial line of the hole d. During trimming, the impact of the matrix on the burrs is transferred to the forging and straightens it. The editing scheme proposed in the claimed invention is similar to the V-bending scheme (Moshnin E.N., reference book “Forging and Die Forging of Steel”, edited by M.V. Storozhev, volume 2, p. 167, fig. 2, ed. “ Engineering ", M., 1968), and the bending force is transmitted through the trimmed burr. The condition for editing the curvature of the forgings in the form of bending of the head should be the fulfillment of the ratio:

Rob .≥ Rib., (1)

where is robr. - burr cutting force;

Rib. - the required effort is flexible over a section passing along the centerline of the hole d.

When bending, the magnitude of the normal stresses in the cross section of the bent part depends on the bending moment, and tangents on the magnitude of the transverse force. With a decrease in the distance between the supports L, the bending moment also decreases during bending with a distance L <4 h, where h is the thickness of the part, when calculating the bending force, one should proceed from the shear force: Q≈ 0.5 · F bend · G _B (Moshnin E .N., Handbook “Forging and Die Forging of Steel” under the editorship of MV Storozhev, volume 2, p. 169, file (5), publishing house “Engineering”, M., 1968),

where is the bend. - the cross-sectional area of the forgings along the center line of the hole d;

G _B - temporary tensile strength of the material of the bent part.

The distance L at the beginning of trimming is defined as the length of the projection of the burrs on the longitudinal axis of the forging, during the dressing process, the value of L will be further reduced. For a nomenclature of type I wrenches with an internal hexagon, forged, double-sided, straight, the ratio L <4 h is fulfilled (“Special socket wrenches”, Technical specifications TU2-035-550-95, Pavlovsky Tool Plant JSC, 1996).

The required bending force for the section along the centerline of the hole d:

Rig. = Q · L / B≈ 0.5 · Fb · G _B · L / B, (2)

where B is the distance from the edge of the head of the key to the centerline of the hole d.

The burr cutting force is determined by the ratio (Brukhanov A.N., Handbook “Forging and Die Forging of Steel”, edited by MV Storozhev, vol. 2, p. 255, ed. “Mechanical Engineering”, M., 1968) :

Rob. = (1.5-1.8) G _B Fcp, (3)

where G _B - temporary tensile strength;

Fcp = t · lcp is the cut area;

t is the thickness of the trimmed burrs;

lcp is the perimeter of the slice.

Substituting expressions (2) and (3) in relation (1), the condition for editing the curvature of the forgings of the socket wrenches is specified in the following form:

(1.5-1.8) · G _B · Fcp≥ 0.5 · F bend · G _B · L / _B.

Taking on the left side the minimum values of quantities and thereby weakening the inequality, the condition for editing the forgings can be represented as:

1.5 · Fcp min≥ 0.5 · Fg · / V; or Fbo ≤ 3 · Fcp min · V / L, (4)

where Fcp min is the minimum cut area of the burrs, taking into account the maximum size of the matrix, the minimum size of the forging and taking into account the cutoff curves at the transition from the body of the forging to the burrs.

The equality of the left and right sides of the relation (4) establishes the greatest value of Fb at which the effect of editing the distortion of the forgings of the socket wrenches begins. If the right-hand side of the relationship is equal or exceeds, after forging, the head of the forgings comes into contact with the covering support surface of the punch 12. Since the cutting matrix 10 has a cavity 11 for freely accommodating the key head, local cutting of the head and forging rod 1 and deformation of the internal hexagonal cavity are excluded after cutting. .

Example. A serial die was made and mastered in production for punching holes, trimming burrs and straightening the bend of the forging head of a straight double-sided socket wrench from 40X steel in hot form with head dimensions: S = 27 mm; D = 39.1-40.5 mm; L = 65 mm; B = 46 mm; h = 21 mm; d = 20 mm; Flex = 385.4 mm.

Truncated burrs 3 are formed along the line of the matrix connector when receiving forgings on the gas condensate field. The thickness of the cut burrs t = 1 mm, the perimeter of the cut t = 135 mm, the radius of curvature when passing from the body of the forging to the burrs r = 1.5 mm. The size along the width of the cutting contour of the edged matrix is U = 39.69-40.31 mm.

Maximum residual burr protrusion when trimming:

e = (Umax-Dmin) / 2 = (40.31-39.1) = 0.6 mm.

For e = 0.6 mm, the thickness of the cut, taking into account the radius of curvature r = 1.5 mm, is determined graphically or by calculation: t min = 1.6 mm. Minimum cutting area: Fcp min = tmin · lav = 1.6 · 135 = 216 mm ² . Fulfillment of the editing condition (4):

F bend ≤ 3 · Fcp min · V / L; 385.4 <3 · 216 · 46/65 = 458.6 - satisfied.

The stamp works as part of a stamping line. After disembarking the head of the key on the gas-condensate field, the forging is hot conveyed by the conveyor to the die. First, the hole d is punched, then the burr 3 is cut along the head contour. Operations on the stamp are performed in a hot state with one heating. After punching the hole, a slight bending of the head relative to the rod is formed. When trimming the burrs, the matrix rests on the burrs and straightens the limb of the head, and during the further course, trims the burrs. The half-open cut matrix is contacted with the forging only through the side burrs, therefore, cases of crushing and deformation of the rod and key head during operation are not observed. The design of the serial stamp, made in accordance with the claimed invention, in production has shown its efficiency. The quality of the forgings meets the established requirements.

Thus, the use of the claimed invention eliminates the disadvantages of the known sequential die used for trimming burrs and flashing holes in the forgings, and perform hole punching, burr trimming and straightening of the forgings of double-sided straight socket wrenches according to the claimed invention, to comply with the established requirements for quality. This result is ensured by changing the design and layout of the known stamp.

Claims (1)

Serial stamp for punching, trimming and straightening forgings of socket wrenches, containing upper and lower plates with guide columns, punch punch mounted on the top plate, puller, die for punching with a hole in the hole, half-open cutting matrix with a cutting edge and a cutting punch with covering surface, characterized in that the semi-open edging matrix is mounted on the upper plate and is made with a cavity located behind the cutting edge of the cutting edge for free placement of the forging head Nogo key cut punch is secured to the bottom plate, and covering its surface is made of the supporting conditions for ensuring fixation of the forging during the trimming and straightening.

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