JP2006136892A - Method for opening through-hole on peripheral wall of workpiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To open a through-hole by punching with a press without generating burrs on the peripheral wall of a tube part. <P>SOLUTION: The through-hole 70 is opened by forming a circular dent part 74 having an inner peripheral surface 75 by shearing which is slightly larger than the through-hole 70 in a diameter by press working in a predetermined position for opening the through-hole from the outside of the tube part 71 and driving a punch 53 which is smaller than the dent part in the diameter in the position corresponding to the dent part from the inside of the tube part. Because the inner peripheral surface of the dent part 74 is a shear plane and the shear plane is not pulled out to the outside by driving the punch, a fracture surface and the shear plane coincide in the inside of the through-hole. That is, the occurrence of burrs on the edge of the hole is prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for opening a through hole in a peripheral wall of a cylindrical portion of a workpiece having a cylindrical portion, such as a body of a hydraulic valve lifter, a through hole opening device, and a workpiece having a through hole.

In order to open a through hole in a plate material, cutting with a drill, punching of a press, electric discharge machining, and the like can be performed.
However, in drilling with a drill or a press, burrs are generated at the hole edge, which takes time for deburring. Electrical discharge machining has a problem that it takes a long machining time and productivity is low.
On the other hand, as shown in FIGS. 13a and 13b, there has been proposed a method of opening a through hole without causing burrs by punching a plate (7b) with a press (Patent Document 1).
In this process, a circumferential groove (74a) corresponding to the diameter of the through hole (70a) to be punched is formed on at least the back surface of the plate (work) (7b) by primary processing by pressing or cutting (see FIG. 13a). As shown in FIG. 5, the punching punch (51a) is driven from the opposite side surface of the plate (7b) to the position corresponding to the center of the circumferential groove by the secondary processing by pressing to open the through hole (70a).
In the method shown in FIG. 13, when the peripheral groove (74a) is formed by cutting with a cutting tool, the machining efficiency is poor. When the circumferential groove (74a) is opened by press working, the plate material (7b) is plastically deformed and warped, which deteriorates the accuracy during the secondary processing and deteriorates the yield.

Further, as a method of opening a through hole without causing burrs, a method shown in FIGS. 14a and 14b is also disclosed in the literature (Patent Document 2).
As shown in FIG. 14a, the plate material (7b) is positioned between the presser punch (51c) and the die (31a), and the push-up punch (31b) is first lifted from below the die (31a) by a primary process. Thus, an upward half-punched portion (73a) is formed on the lower surface of the plate (7b). Next, by a secondary process, the bulging portion (73b) swelled upward by the half punching is punched from above by a punching punch (51d) and a die (31c) different from the above.
However, the relationship between the inner diameter of the half punched portion (73a) and the diameter of the punching punch (51d) is not described.
The outer diameter of the bulging part (73b) is naturally larger than the inner diameter of the half-blanked part (73a). If the diameter of the punching punch (51d) is made slightly smaller than the inner diameter of the half punching part (73a), it is considered that no burr is formed at the lower end opening edge of the punching through hole (70a), but the through hole (70a) At the upper end opening edge, the outer peripheral edge of the bulging portion (73b) remains higher than the upper surface of the plate (7b). That is, the result is the same as when burrs are formed on the upper surface side of the plate (7b).
If the diameter of the punching punch (51d) is made larger than the outer diameter of the bulging portion (73b), it is clear that burrs are generated at the punching hole edge.
In any case, as shown in FIG. 14b, the upper and lower edges of the through hole (70a) are certainly not square.

FIG. 12 shows a small-diameter cylindrical body (7a) of the hydraulic valve lifter, and a through-hole (70) for inflow of engine oil is formed in the peripheral wall (72) of the body (7a).
When the through hole (70) is opened by drilling or punching from the outside of the body, as described above, burrs are generated at the hole edge, and it takes time to perform post-processing for deburring. Since the body (7a) is cylindrical, the workability of deburring is also worse than in the case of a plate material.
Also, when the through hole (70) is opened from the outside of the cylindrical body (7a) by punching the press, the punched residue (78a) is discharged into the body (7a), and the effort to take out the punched residue from the body (7a) It also takes.
When trying to open the through hole (70) by the method shown in FIG. 13, there are the following problems.
First, in the method shown in FIG. 13, when the work is planned to be a flat plate, and the work is a small diameter cylindrical body (7a), the work is placed on the back side of the work, that is, on the inner surface of the tubular body (7a). Hesitated as a means of opening a ditch.
Even if a circumferential groove is provided on the outer peripheral surface of the tubular body (7a) and the through hole (70) is punched from the inside of the body (7a), it is still arranged in the through hole (70). Whether to open a corresponding circumferential groove and how to punch from the inside to the outside of the small-diameter tubular body (7a) by what punch is considered.
For example, an annular ridge corresponding to the circumferential groove is formed on the outer peripheral edge of the punch tip, and a circumferential groove corresponding to the diameter of the through hole (70) is formed on the peripheral wall (72) of the body (7a) by driving the punch. Even so, a load is not applied evenly to the annular ridges on the peripheral surface of the tubular body (7a), and the ridges are quickly worn out. Further, it is difficult to correct the polishing for the annular ridges, and it is not practical in terms of durability.

  Even if it is going to open the said through-hole (70) by the method shown in FIG. 14, since the method is not certain as mentioned above, it cannot implement.

Japanese Patent Laid-Open No. 5-42330 ([0005], [0006], [0009], [0019], etc.) JP 2000-301261 A ([0004], [0005])

As a result of diligent efforts, the applicant devised the punch and succeeded in punching the through-hole from the inside to the outside of the small-diameter cylindrical body (7a). However, the Bali problem remains.
In addition, as shown in FIG. 12, when the through hole (70) is applied to the step (73) on the outer periphery of the body (7a), in the embodiment, the inclined step, an offset load acts on the punch, thereby extending the life of the punch. The problem of shrinking remained.
The present invention does not cause burrs on the peripheral wall of the cylindrical part of the workpiece having the cylindrical part, and even when a step is generated on the outer periphery of the peripheral wall and the through hole is opened on the step, The method, the apparatus and the work which opened the through-hole can be clarified so that the through-hole can be opened without shortening the service life and without generating burrs.

  According to the first aspect of the present invention, the through-hole opening method includes the cylindrical portion (71) in a state where the cored bar (5) for preventing inward deformation of the inner surface of the cylindrical portion at the through-hole opening planned position is inserted into the cylindrical portion (71). From the outside of the through hole to the opening planned opening position, drive the shaft part (31 ') whose tip is cylindrical and the tip surface is flat with respect to the cylinder axis, and slightly larger than the through hole (70) to be opened A circular recess (74) having an inner peripheral surface (75) and a flat bottom surface by shearing in diameter is formed, and a recess (from the inside of the cylindrical portion (71) to a position corresponding to the recess (74) ( 74) A through hole (70) is opened by punching a slightly smaller diameter punch.

  Claim 2 is the method for opening a through hole according to claim 1, wherein the cored bar (5) is disposed at a position corresponding to the through hole (70) to be opened and the inner surface of the cylindrical part (71) in a wider range of the through hole (70). The through hole opening method according to claim 1, wherein the presser punch (51) that hits the boss is protruded short.

Claim 3 includes a crushing step, a drilling step, and a drilling step in the through-hole opening method according to claim 1 or 2, wherein in the crushing step, the metal core (5) is fitted in the cylindrical portion (71), and the cylindrical portion Crush punch (31) from the outside of (71) to the through-hole opening planned position to form a circular recess (74) on the outer surface of the cylindrical peripheral wall (72),
In the drilling step, the drilling punch (52) is driven from the inside of the cylindrical part (71) at a position corresponding to the concave part (74), and the peripheral wall (72) has a bottom having a smaller diameter than the concave part (74). Open a hole (76)
In the perforating step, a perforated punch (53) having a slightly smaller diameter than the perforated punch (52) is driven from the inside of the cylindrical portion (71) into a position corresponding to the bottomed hole (76), and the bottomed hole (76) A through hole (70) is opened by punching the bottom of the plate.

  According to a fourth aspect of the present invention, in the through hole opening method according to any one of the first to third aspects, a step portion (73) is formed on the outer surface of the peripheral wall (72), and the step portion (73) is hung on the through hole (70). ) And the recess (74) is applied lower than the lower part of the step (73).

As shown in FIG. 2, the through-hole opening device of claim 5 has first, second, and third three stations (S1, S2, S3), and a workpiece having a cylindrical portion (71) ( 7) is moved in order from the first station (S1) to the third station (S3), and is sequentially pressed at each station (S1, S2, S3), and the peripheral wall (72) ) A device that opens a through-hole (70) having a smaller diameter,
Each station (S1), (S2), and (S3) are arranged in a die block (3) and a die block (3) so as to be able to approach and separate from each other, and a core ( 5)
The die block (3) of the first station (S1) has a circular recess (74) having a slightly larger diameter than the through hole and having an inner peripheral surface by shearing at the position where the through hole is to be opened in the cylindrical part (71). Crushing punch (31) for forming,
The core bar (5) of the second station (S2) has a punch (52) projecting toward the die block (3) side of the station (S2), and the punch (52) has a cylindrical portion ( 71) having a diameter smaller than that of the recess (74), capable of being pushed in halfway through the wall of the peripheral wall (72) of the cylinder, and having a length that can be accommodated in the cylinder (71) including the core metal (5). Yes,
The core bar (5) of the third station (S3) is provided with a perforated punch (53) toward the die block (3) side of the station (S3), and the punch (53) is connected to the second station (S2). ) Perforated punch (52) is slightly smaller in diameter than the bottomed hole (76) formed by driving the peripheral wall (72) of the cylindrical part, and the bottom of the bottomed hole (76) can be punched and the The length is within the cylindrical part (71) including the cored bar (5), and the die block (3) of the third station (S3) has a hole (78) for discharging the through hole punched residue (78). 32) has been established.

  According to a sixth aspect of the present invention, a work having a cylindrical portion has a through hole (70) formed in the cylindrical peripheral wall (72) by the method according to any one of the first to fourth aspects.

The through-hole opening method according to claim 1 has an inner peripheral surface (75) and a flat bottom surface by shearing at a position where the through-hole is to be opened from the outside of the cylindrical portion (71), and has a slightly larger diameter than the through-hole (70). After forming the recess (74), a through hole (70) is established by driving a punch with a smaller diameter than the recess (74) into the position corresponding to the recess (74) from the inside of the work (7). Therefore, on the punching side of the punch, the fracture surface of the meat due to the punching is continuous with the inner peripheral surface (75) due to the shearing of the concave portion (74), so that the meat of the peripheral surface (75) is pulled out to the outside. There is nothing. That is, no burr is generated at the hole edge.
In addition, since the recess (74) is formed in advance on the side opposite to the punch driving side, the punch length can be shortened corresponding to the depth of the recess, which can prevent punch breakage and prolong the life of the punch. I can do it.
Further, since the punch is pushed in from the inside of the tube portion (71) to open the through hole (70), the punched residue (78) is automatically discharged to the outside of the tube portion (71), and the tube portion (71) It is possible to save the trouble of taking out the residue (78).
In addition, formation of the recessed part (74) to a cylinder part (71) outer peripheral surface is the core part (5) which prevents the inward deformation | transformation of the cylinder part inner surface of a cylinder part (71) in a through-hole opening plan position. Since the shaft portion (31 ′) is pushed from the outside of the tube portion (71) in the inserted state, inward deformation of the tube portion (71) is prevented and the original shape of the tube portion (71) is damaged. There is no.
In addition, the shaft (31 ') has a cylindrical shape and the tip is formed on a flat surface perpendicular to the cylinder axis, so even if the tip of the shaft (31') is worn out, it can be easily polished and used repeatedly. it can.

  According to a second aspect of the present invention, there is provided a through hole opening method in which the inner surface of the cylindrical portion (71) corresponding to the through hole (70) to be opened is pressed by the presser punch (51) protruding from the core bar (5). Inward deformation of (71) can be prevented.

  In addition to the crushing step for forming the recess (74), the through-hole opening method of claim 3 forms a bottomed hole (76) by driving a drilling punch (52) at the through-hole opening planned position. After that, in order to punch out the bottom of the bottomed hole (76) by punching the perforated punch (53) into the bottomed hole (76), compared to punching the peripheral wall (72) at a time punch (52) (53) This reduces the load on the punch and extends the punch life.

  The through hole forming method according to claim 4 secures a flat bottom by forming a recessed portion (74) having a slightly larger diameter than the through hole (70) in advance from the outside of the cylindrical portion (71) at a position where the through hole is to be opened. Therefore, the stepped portion does not exist at the through hole opening planned position. For this reason, it is possible to prevent the bias life from acting on the punch driven into the peripheral wall (72) from the inside of the cylindrical portion (71) and shortening the life of the punch.

The through-hole opening device according to claim 5 can form a recess (74) in the through-hole opening planned position of the cylindrical portion (71) by the crushing punch (31) of the first station (S1), and the second station (S2 ) Drilling punch (52) can open a bottomed hole (76) from the inside of the cylindrical part (74) to the position where the through hole is to be opened, and the third station (S3) drilling punch (53) is used to open the bottomed hole. A through hole (70) can be opened by punching the bottom of (76).
The workpiece (7) can be supported by fitting its cylindrical portion (71) to the core bar (5) of each station, and the workpiece (7) is sequentially moved from the first station (S1) to the third station (S3). By feeding in, the through hole (70) can be efficiently opened in the peripheral wall (72) of the work cylinder portion (71).

  The work (7) of claim 6 has no through burr at the hole edge because the through hole (70) is opened by the method of any one of claims 1 to 3.

In the embodiment, the workpiece (7) to be machined is a body (7a) of the hydraulic valve lifter shown in FIG. 12, and a through hole (70) is opened in the peripheral wall (72) of the cylindrical portion (71) of the body. It is. The front portion of the tube portion (71) is closed.
A step portion (73) inclined around the outer surface of the cylindrical portion (71) and inclined in the axial direction is formed at the planned opening of the through hole.
The outer diameter of the cylindrical portion (71) is about 16 mm, the inner diameter is about 10 mm, the length is about 40 to 50 mm, and the diameter of the through hole (70) is slightly smaller than the wall thickness of the cylindrical portion (71).

FIG. 1 shows the order of processing steps. In the crushing step shown in FIG. A, the crushing punch (31) is driven from the outside of the cylindrical portion peripheral wall (72) toward the axis of the cylindrical portion (71) (accurately). In this case, “the work (7) is crushed and driven into the punch (31)”), the recess (74) lower than the lower part of the step (73) is formed. The diameter D of the recess (74) is slightly larger than the diameter of the through hole (70).
The front end portion (upper end portion) of the crushing punch (31) is formed as a short cylindrical shaft portion (31 ′), and the front end surface is a flat surface orthogonal to the cylindrical shaft core.
The inner peripheral surface of the recess (74) is a sheared surface (75) that is sheared by the tip shaft portion (31 ') of the crushing punch (31).
When the tip shaft portion (31 ′) of the crushing punch (31) bites into the peripheral wall (72), the presser punch (51) that prevents the wall of the peripheral wall (72) from bulging inward is formed on the inner surface of the peripheral wall (72). Hit.
In the drilling step shown in FIG. b, the punching punch (52) is driven from the inner side of the cylindrical part peripheral wall (72) toward the outer side in the radial direction of the cylindrical part at the position corresponding to the recessed part (74). Open hole (76). When the punch (52) is driven into the peripheral wall (72), the work (7) is received by the die block (3).
The diameter of the punch (52) is slightly smaller than the diameter of the recess (74).
The inner peripheral surface of the bottomed hole (76) is also a sheared surface that has been sheared by the perforated punch (52).
The bottom (77) of the pushed meat (78a) enters the recess (74) and slightly protrudes from the opening edge of the recess (74) on the lower side of the inclined step (73).
In the perforating step shown in FIG. c, the perforated punch (53) is driven into the bottomed hole (76) from the inner side of the cylindrical part peripheral wall (72) toward the outer side in the radial direction of the cylindrical part. Open the through hole (70) by punching the bottom outward.
When the perforating punch (53) is driven into the bottomed hole (76), the work (7) is received by the die block (3).

FIG. 2 shows a punching unit (11), (12) in each of the first station (S1) that performs the crushing process, the second station (S2) that performs the drilling process, and the third station (S3) that performs the drilling process. 13) is shown.
Each punching unit (11), (12) and (13) includes die blocks (3), (3) and (3) and cored bars (5), (5) and (5). Punches (51), (52), and (53) are provided so as to protrude downward on each core bar (5).
The work cylinder part (71) is fitted to the metal core (5) located above the die block (3), the metal core (5) is lowered, and the work (7) is received by the die block (3) to punch ( 52) (53) is driven into the peripheral wall (72) from the inside of the cylindrical portion (71) of the work (7). However, in the first station (S1) where the crushing process is performed, the presser punch (51) simply presses against the inner surface of the work cylinder (71) and does not drive into the peripheral wall (72). A recess (74) is formed on the corresponding outer peripheral surface by a crushing punch (31).
Each of the punching units (11), (12) and (13) is connected to the die block (3) via the mounting base (2) on the common base (1) as shown in FIGS. A metal core (5) is attached.
The mounting base (2) has a right wall plate (22) and a left wall plate (23) protruding from the rear of the bottom plate (21), and a rear wall plate between the rear ends of the left and right wall plates (22) and (23). Closed at (24).

The die block (3) is placed in front of the bottom plate (21) of the mounting base (2) and straddles the right wall plate (22) and the left wall plate (23) to the wall plate (22) (23). It is fixed with bolts.
In the center of the upper surface of the die block (3), a shallow groove (30) corresponding to the outer periphery of the work (7) is opened in the front-rear direction so that the work (7) can be stably received.
When the die block (3) receives the workpiece (7) in the groove portion (30), the vertical hole (32) whose upper end is reduced in diameter at a position corresponding to the planned opening of the through hole of the workpiece (7). Has been opened through.

As shown in FIG. 2a, an axial crushing punch (31) is inserted into the vertical hole (32) of the die block (3) of the first station (S1), and the crushing punch (31) has an angular top edge. Corresponding to the shape of the recess (74) of the work (7), the upper end protrudes upward from the groove (30) corresponding to the depth of the recess (74).
As described above, the tip (upper end) of the crushing punch (31) is formed as a short cylindrical shaft (31 ′), and the tip is a flat surface perpendicular to the cylinder axis.
The crushing punch (31) is supported by a cradle (33) provided on the bottom plate (21) of the mounting base (2) and is prevented from moving downward.

As shown in FIGS. 3 and 5, the elevating block (4) can be moved up and down in a space surrounded by the three wall plates (22), (23), (24) and the die block (3) of the mounting base (2). Is done.
In the upper part of the lifting block (4), a mandrel mounting hole (41) is opened in the front-rear direction, and the shaft-shaped mandrel (5) leaves the front part in the mandrel mounting hole (41). Inserted. The protruding portion of the cored bar (5) from the elevating block (4) is located directly above the groove (30) of the die block (3).
The elevating block (4) has a spring accommodating hole (42) opened from the bottom side, and is urged upward by a spring (44) accommodated in the spring accommodating hole (42). The raising / lowering block (4) in the raised position can be lowered by the gap between the bottom surface of the block and the bottom plate (21) of the mounting base (2). The rising end height of the lifting block (4) is regulated by a rising end regulating means (not shown).
The spring (44) is supported by a spring pressure adjusting base (45) screwed to the bottom plate (21) of the mounting base (2), and the spring pressure can be adjusted by tightening or loosening the adjusting base (45). .
The elevating block (4) has a clamp bolt (43) reaching the core metal mounting hole (41) on the side surface of the block, and the core metal (5) can be fixed by tightening the clamp bolt (43).
Punches (51), (52) and (53) projecting from each metal core (5) are fitted to the metal core (5) by fitting the cylindrical part (71) of the work (7) to the opening of the cylindrical part (71). The side end face is in contact with the elevating block (4), and corresponds to the through hole scheduled opening position of the work (7).

  The base (1) is fixed to the base (not shown) of the press device, and each lifting block (4) (4) (4) is moved from the standby position by the lowering of the ram (not shown) of the press device. 44) Against 44), when the ram rises, it returns to the standby position all at once by the spring force.

A stripper (6) is provided in the die block (3) of the second station (S2) and the third station (S3).
The stripper (6) has a contact plate (62) projecting from a block body (61) fixed to the upper surface of one end of the die block (3) with a bolt toward the upper portion of the core metal (5).

As shown in FIG. 6, the core bar (5) is lowered to the height method corresponding to the portion W that fits into the cylindrical part (71) of the work (7) at the top end of each core bar (5). A cut portion (50) is formed. As shown in FIGS. 7 and 8, the cut portion (50) is cut in an arc shape along the inner peripheral surface of the work cylinder portion (71).
The core metal (5) of the first station (S1) has a presser punch (51), the metal core (5) of the second station (S2) has a punch punch (52), and the metal core of the third station (S3). In (5), a perforated punch (53) is projected downward at a position directly above the hole (32) of the lower die block (3).
The peripheral edge of the punching side of each punch is angular.
As shown below, although the lengths of the presser punch (51), the punching punch (52), and the punching punch (53) are different, as shown in FIGS. 6 and 7, the cut portion (50) of each cored bar (5) The distance H1 from the punch to the tip of the punch (51) (52) (53) is almost uniform within the range that can be inserted into and removed from the cylindrical portion (71) of the workpiece (7), and the protrusion length of the punch is increased. The depth H2 of the cut portion (50) of the cored bar (5) is increased.

The presser punch (51) of the first station (S1) is dented by driving the tip shaft portion (31 ') of the crushing punch (31) from the outside of the peripheral wall (72) of the work (7) as described above. When forming (74), it is intended to prevent the meat from locally expanding on the inner surface of the peripheral wall (72).
If the peripheral surface of the core bar (5) is in contact with the inner surface of the peripheral wall (72), the presser punch (51) can be omitted.
In the case of the embodiment, as shown in FIG. 12, there is a slight step on the inner surface of the cylindrical portion (71) of the work (7), and the peripheral surface of the cored bar (5) cannot be applied to the through hole opening planned position. A presser punch (51) having the same length as the step is protruded from the peripheral surface of the cored bar (5).
It is desirable that the tip diameter of the presser punch (51) be able to press the range of the peripheral wall (72) on the inner surface of the peripheral wall (72) beyond the range corresponding to the recessed part (74). It is larger than the diameter D of 74).

  The diameter of the punch (52) in the second station (S2) is slightly smaller than the diameter of the recess (74), and the length can be driven to about 1/2 of the wall thickness of the peripheral wall (72). Length.

  The diameter of the punch punch (53) at the third station (S3) is slightly smaller than the diameter of the punch punch (52) at the second station (S2), that is, the bottom hole (76) of the workpiece (7). The length is slightly smaller than the diameter, and the length is such that the bottom of the bottomed hole (76) can be punched. It is not necessary for the tip of the punching punch (53) to reach the bottom of the recessed portion (74) of the work (7), and when the punch is driven to a depth approaching the bottom of the recessed portion (74), a through hole (70) is established. .

It is essential that the diameter D of the recess (74) is larger than the diameter of the punching punch (53), but how much larger the diameter D depends on the diameter of the punching punch (53), the material of the workpiece (7), and the wall thickness. Although it depends on conditions such as the depth of the bottomed hole (76), it has been empirically understood that the following formula can be used.
Recessed portion diameter D = Drilling punch diameter + {2 × (plate thickness × 5-12%)}
If the diameter of the recess (74) deviates from the above formula and is too large or too small, the effect of not generating burrs is not obtained.

However, the lifting / lowering block (4) is fitted in the state where the cylindrical portion (71) of the work (7) is fitted to the core bar (5) of the first station (S1) until the opening edge of the cylindrical portion hits the lifting / lowering block (4). Lower. The presser punch (51) on the core bar (5) presses the cylindrical wall (72) (FIG. 9a), and at the same time, the tip shaft (31 ') of the crushing punch (31) is driven into the through hole opening planned position. A recess (74) is formed (FIG. 1a).
What is important here is that since the peripheral edge of the tip shaft portion (31 ′) of the crushing punch (31) is angular, the inner peripheral surface (75) of the concave portion (74) becomes a shear surface (75). is there. Further, since the tip end surface of the shaft portion (31 ′) is a flat surface orthogonal to the shaft core, the bottom surface of the recess portion (74) is formed flat.

The work (7) in which the recess (74) is formed at the first station (S1) is removed from the metal core (5), and the metal core (2) of the second station (S2) is left with the recess (74) facing down. 5) The lifting / lowering block (4) is lowered while fitting the cylindrical portion (71) of the work (7) until the opening edge of the cylindrical portion hits the lifting / lowering block (4).
A hole punch (52) on the metal core (5) is driven from the inside of the peripheral wall (72) into the position corresponding to the recess (74) (Fig. 9b), and a hole with a bottom (76) is opened. (FIG. 1b).
The bottom (77) of the pushed meat (78a) enters the recess (74) and slightly protrudes from the opening edge of the recess (74) on the lower side of the step (73). This protrusion (77) escapes into the hole (32) of the die block (3).
The inner peripheral surface of the bottomed hole (76) is a sheared surface.
When the elevating block (4) moves up to the standby position, the work (7) hits the contact plate of the stripper (6) (62) and the drilling punch (52) comes out of the bottomed hole (76), and the core It becomes possible to remove the workpiece (7) from the gold (5).

The work (7) in which the bottomed hole (76) is formed in the second station (S2) is removed from the metal core (5), and the cylindrical part (5) of the work (7) is attached to the metal core (5) of the third station (S3). 71) is lowered with the opening of the bottomed hole (76) facing upward (FIG. 9c) in a state in which the opening edge of the bottomed hole (76) is directed straight up.
A perforation punch (53) on the metal core (5) punches the bottom of the bottomed hole (76) to open a through hole (70) (FIG. 1c).
As shown in FIG. 2c, the punched residue (78) is discharged outside through the hole (28) of the mounting base (2) and the hole (10) of the base (1) from the hole (32) of the die block (3). Is done.
When the elevating block (4) moves up to the standby position, the work (7) hits the contact plate (62) of the stripper (6), and the punching punch (53) comes out of the work (7).

When the bottom of the bottomed hole (76) is punched, on the punching side of the punch, the fracture surface of the meat due to punching is continuous with the inner peripheral surface (75) due to shearing of the recess (74). (75) meat will not be pulled out. That is, no burr is generated at the hole edge.
For this reason, the processing process for deburring can be eliminated like the conventional press punching and opening of the through-hole by a drill.
Further, the punching of the press requires a shorter processing time than the opening of the through hole by electric discharge machining, and the productivity can be improved.
Further, since the recess (74) having a diameter slightly larger than the diameter of the through hole (70) to be punched is formed in advance on the side opposite to the punching side of the punching punch (53), the length of the punching punch (53) is Corresponding to the depth of the dent (74), it can be shortened, the breakage of the punching punch (53) can be prevented and the life can be extended.

  Since the bottom surface of the recessed portion (74) on the outer peripheral surface of the cylindrical portion (71) is flat, there is no stepped portion at the position where the through hole is to be opened. For this reason, it is possible to prevent the bias life from acting on the punch driven into the peripheral wall (72) from the inside of the cylindrical portion (71) and shortening the life of the punch.

Although the movement of the workpiece (7) between the stations (S1), (S2) and (S3) and the insertion of the workpiece tube portion (71) into each core bar (5) can be performed manually, a transfer device (not shown) Of course, the work efficiency can be further improved if it is automatically performed in step).
Example 1

The cylindrical portion (71) has an outer diameter of 16 mm, an inner diameter of 10 mm, and a length of 40 mm.
In FIG. 1a, the wall thickness t1 on the high side is 3 mm, the wall pressure t2 on the low side is 2.5 mm, and the crushing punch (31) is bordered by the step (73) on the outer peripheral surface of the cylindrical wall (72). The diameter D of the recess (74) formed by the driving is 2.2 mm, and the depth L1 of the recess (74) is 0.5 mm on the thin side.
In FIG. 2b, the diameter of the perforated punch (52) is 1.75 mm, and the depth L2 of the bottomed hole (76) formed by the perforated punch (52) is 0.9 mm.
In FIG. 2c, the diameter of the perforated punch (53) is 1.70 mm.
A through hole (70) with no burr was established.

In the embodiment, the die block (3) of each station (S1) (S2) (S3) has the same shape for compatibility. That is, the shape of the hole (32) penetrating in the vertical direction of the die block (3) is the same, but the die block (3) of the second station (S2) is perforated even if it is not the through hole (32). By punching in the punch (52), it is only necessary to form a recess that allows the flesh protruding slightly from the opening edge of the recess (74) in the cylindrical peripheral wall (72) to escape.
The shape of the hole (32) of the die block (3) of the third station (S3) is not limited as long as it has a function of discharging the scrap (78).

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

In the present invention, after opening the recessed portion (74) on the outer peripheral surface of the work cylinder portion (71), it penetrates to the corresponding position with the recessed portion (74) in one step from the inside of the tube portion (71). Of course, it includes the opening of holes.
In this case, the productivity is improved by reducing one machining step, but the punching thickness becomes large and the load load increases, which is disadvantageous for the durability of the punch.

It is process explanatory drawing. It is explanatory drawing of the unit according to station. It is a slope view of a unit. It is a left view of the unit which partly fractured It is a top view of a unit. It is a side view of a metal core and a punch. It is a front view of a metal core and a punch. It is explanatory drawing which shows the state which a workpiece | work hits a stripper. It is explanatory drawing according to station of the state in which a punch is driven into the thickness of a work cylinder part. It is a top view of a die block. It is sectional drawing of the periphery on the hole of a die block. It is sectional drawing of a workpiece | work. It is explanatory drawing of the opening procedure of the conventional burr-free through-hole. It is explanatory drawing of the opening procedure of the other conventional burr-free through-hole.

Explanation of symbols

2 Mounting base 3 Die block
31 Crushing punch
32 Hole 4 Lifting block 5 Core 7 Workpiece
70 Through hole
71 Tube
72 perimeter wall
73 Inclined step
74 dent
75 Inner surface
76 Bottom hole

Claims (6)

It is a method of opening a through hole in which a burr does not occur by punching a press on a peripheral wall of the cylindrical portion of a workpiece having a cylindrical portion,
With the mandrel that prevents inward deformation of the inner surface of the cylindrical portion at the position where the through hole is planned to be opened inserted into the cylindrical portion, the tip is cylindrical and the tip surface is the cylindrical axis from the outer side of the cylindrical portion to the planned through hole opening position. By driving a flat shaft portion against the core, forming a circular recess having a slightly larger diameter than the through-hole to be opened and having an inner peripheral surface and a flat bottom surface by shearing, from the inside of the cylindrical portion, A method for opening a through hole in a work peripheral wall, wherein a punch having a slightly smaller diameter than that of a dent is driven into a position corresponding to the dent to open a through hole.   The through hole opening method according to claim 1, wherein the core metal has a presser punch that projects on the inner surface of the cylindrical portion at a position wider than the through hole at a position corresponding to the through hole. Including crushing process, drilling process and drilling process,
In the crushing process, a metal core is fitted into the cylinder part, and a crushing punch is driven from the outside of the cylinder part to the through-hole opening planned position to form a circular recess on the outer surface of the peripheral wall,
In the drilling step, a hole with a bottom is formed in the peripheral wall by punching a punch from the inside to the outside at a position corresponding to the recess, and opening a bottom hole smaller than the recess.
In the drilling step, a perforation punch having a slightly smaller diameter than the drilling punch is driven from the inside of the cylindrical portion at a position corresponding to the bottomed hole, and the through hole is formed by punching out the bottom of the bottomed hole. 2. A method for opening a through hole in the work peripheral wall according to 2.   The work peripheral wall according to any one of claims 1 to 3, wherein a stepped portion is formed on an outer surface of the peripheral wall, a through hole is formed in the stepped portion, and the recessed portion is formed lower than a lower portion of the stepped portion. Through hole opening method. The first, second, and third stations are provided, and the workpiece having the cylindrical portion is moved in order from the first station to the third station, and press work is sequentially performed at each station to form a through hole in the peripheral wall of the cylindrical portion. A device to be opened,
Each station includes a die block and a core bar that is disposed so as to be able to approach and separate from the die block and is fitted in and supported sideways so that the cylindrical portion can be inserted and removed.
The die block of the first station has a crushing punch for forming a circular recess having a slightly larger diameter than the through-hole and having an inner peripheral surface by shearing at the planned opening of the through-hole of the cylindrical portion,
The core metal of the second station is provided with a hole punch toward the die block side of the station, and the hole punch has a diameter smaller than that of the recessed portion and penetrates to the middle of the wall thickness of the cylinder portion peripheral wall. It is a length that can be accommodated in the cylinder part including the core metal,
The core metal of the third station has a perforated punch toward the die block side of the station, and the punch has a diameter of a bottomed hole formed by driving the perforated punch of the second station into the peripheral wall of the cylinder portion. The diameter is slightly smaller than that of the bottom hole, so that the bottom part of the bottomed hole can be punched out and fits into the cylinder part including the cored bar. A through-hole opening device to the workpiece peripheral wall.   A workpiece having a cylindrical portion, wherein the through-hole is formed in the peripheral wall of the cylindrical portion by the method according to claim 1.

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