JP4756990B2 - Press working method - Google Patents

Description

  The present invention relates to a press working method, and more particularly to a press working method in which a second through hole is formed by punching around the first through hole of a workpiece provided with a first through hole.

  A member such as a positioning pin is inserted by punching, which is a kind of press work, around the first through hole of the workpiece in which a through hole (hereinafter referred to as “first through hole”) through which a member such as a shaft is inserted is formed. May be formed (hereinafter referred to as “second through hole”). For example, the wheel sensor 6 shown in FIG. 4 is a component of the toothed pulley 2 that constitutes the variable valve timing mechanism 1, and includes a first through hole 7 that is a shaft hole through which the shaft 4 of the toothed pulley 2 is inserted, and a tooth The second through hole 8 is a pin hole through which the positioning pin 5 of the attached pulley 2 is inserted. In the wheel sensor 6, the first through hole 7 is formed by appropriate processing such as press working. Later, the second through hole 8 is formed by punching.

  The above background art is a technique that is made as a part of the manufacturing process when various parts are manufactured by press working, and the applicant of the present application particularly knows the document describing the background art at the time of filing. Not done.

  The variable valve timing mechanism is a mechanism for changing the timing at which the valve opens and closes in accordance with the engine speed in an automobile engine or the like having an air supply / exhaust valve (hereinafter simply referred to as “valve”). The variable valve timing mechanism will be described in detail. A timing belt is used to rotate the camshaft (shaft for opening and closing the valve) in synchronism with the rotation of the crankshaft (shaft driven by the piston of the engine). As shown in FIG. 4, the variable valve timing mechanism 1 is wound around a toothed pulley mounted on the shaft and a toothed pulley mounted on the camshaft side shaft. By causing a phase shift between the shaft 4 and the teeth 3 (the teeth meshing with the timing belt) of one of the toothed pulleys 2 on the crankshaft side or the camshaft side, the valve opening / closing timing is always controlled with respect to the engine rotation. It is changing without being constant. The toothed pulley 2 that causes a phase shift between the shaft 4 and the tooth 3 has a sensor detection unit 9 whose presence or absence is detected by a detector such as a proximity sensor at the outer peripheral portion in order to detect the phase shift. The wheel sensor 6 described above is mounted on the shaft 4 of the toothed pulley 2 and the mounting angle is fixed by a positioning pin 5.

  When the second through hole is formed by punching after the first through hole is formed, distortion occurs in the first through hole. This is because punching is performed around the first through hole so as to form the second through hole, so that the material around the first through hole flows toward the second through hole, in other words, the first through hole. This is because the meat around the hole is pulled toward the first through hole. Specifically, in the diameter dimension of the first through hole, the radial dimension passing through the second through hole becomes longer and the radial dimension perpendicular to the radial direction passing through the second through hole becomes shorter. Occurs. Therefore, even if the first through hole is formed with high dimensional accuracy (diameter dimension, roundness, straightness, etc.) before the second through hole is formed, the second through hole is formed. Later, this high dimensional accuracy is not maintained, and in some cases, the dimension exceeds the allowable range, and the work after forming the second through hole may become a defective product.

  The present invention has been made in view of the above-described situation, and even if the second through hole is formed around the first through hole by punching the work on which the first through hole is formed, the first through hole is provided. An object of the present invention is to provide a press working method capable of maintaining good dimensional accuracy.

The main means taken by the present invention to solve the above problems are as follows:
“In the press working method for forming the second through hole by punching around the first through hole of the work provided with the first through hole,
The portion around the first through-hole, which is generated when the second through-hole is punched out at a portion separated from the second through-hole at an angle of 90 ° with respect to the center of the first through-hole. A press working method characterized by press-molding a recess that produces a strain in the first through hole in a direction opposite to the strain of the first through hole in the same direction as the punching direction of the second through hole.
It is.

  Here, the shape of the recess is not particularly limited, and may be a non-penetrating shape that does not penetrate the front and back of the workpiece, or may be a penetrating shape that penetrates the front and back of the workpiece. Specific examples of the shape include a circle, an oval, a square, and a line shape (a linear shape with a narrow width or a curved shape). Further, in the case of a non-through shape having a bottom, the depth of the bottom may be uniform, or in order to cause a desired distortion in the first through hole, the portion that is greatly distorted is the depth of the bottom. The portion which is deep and is distorted small may have a shallow bottom.

  Further, the “periphery” of the first through hole in which the second through hole and the recess are provided does not need to specify the arrangement position by a specific numerical value, and the second through hole is a part around the first through hole. This shows a portion where the formation of the hole and the recess may cause a strain that is not negligible in the first through hole.

  In the press working method having the above configuration, when the second through hole is formed by punching, naturally, the first through hole is distorted. However, a concave portion that generates a strain in the opposite direction to the strain caused by the first through hole is formed. Since press molding is performed, the strain caused by the first through hole and the strain caused by the recess are partially offset. Therefore, the dimensional accuracy of the first through hole after the formation of the second through hole is not significantly changed as compared with the case where the recess is not formed.

Therefore, according to the method for manufacturing a press-processed product having the above-described configuration, even if the second through hole is formed by punching, the dimensional accuracy of the first through hole can be favorably maintained.
In particular, in the press working method having the above-described configuration, the concave portion is press-formed in the same direction as the punching direction of the second through hole.
Here, the punching direction is the moving direction of the removal portion that moves relative to the remaining portion when the unnecessary portion is removed by shearing the workpiece with a punch and die in punching, which is a type of press working. . The direction of press molding is the direction in which the material moves after deformation with respect to the deformed portion when the workpiece is deformed by pressing the workpiece with the punch and die to follow the punch and die. is there. Therefore, when forming a bottomed concave part by press molding, for example, the direction of press molding is the direction from the inlet of the concave part toward the bottom.
When the concave portion is press-molded in the same direction as the punching direction of the second through hole, in the front and back direction of the workpiece sandwiched between the punch and the die, when forming the second through hole and when forming the concave portion, The meat (material) of the workpiece is pulled (flowed) in the same direction.
Therefore, according to the press working method having the above-described configuration, the distortion generated when the second through hole is formed, or the distortion that can partially cancel the distortion generated when the second through hole is formed, is pressed in the recess. It can be generated accurately by molding, and the high dimensional accuracy of the first through hole can be maintained better.

  In the series of press working steps in which the workpiece is pressed, the step of forming the recess may be before or after the step of forming the second through hole. If the step of forming the recess is a step before the step of forming the second through-hole, the step of forming the second through-hole in advance is expected by distorting the first through-hole in anticipation of distortion generated in the step of forming the second through-hole. In the case of a subsequent process of the hole forming process, it is a process of correcting the distortion generated in the second through hole forming process.

In the above means,
“After pressing the recess, the second through hole is formed by punching”
It is good.

  If the step of forming the recess is a subsequent step of the step of forming the second through hole, the formation of the recess by press molding affects the already formed second through hole, and the second through hole is distorted. The dimensional accuracy of the second through hole may deteriorate.

  On the other hand, if the step of forming the recess is a pre-process of the step of forming the second through-hole, the second through-hole has not yet been formed. It has no effect on the through hole. Therefore, according to the press working method having the above-described configuration, high dimensional accuracy of the second through hole can be ensured satisfactorily.

  As described above, according to the present invention, even if the second through hole is formed around the first through hole by punching the work in which the first through hole is formed, the dimensional accuracy of the first through hole is good. Thus, it is possible to provide a press working method that can be maintained.

  Hereinafter, an example as an embodiment of the press working method according to the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 shows an example of a pressed product 100 manufactured by the pressing method according to the present invention. In this example, a wheel sensor used for the variable valve timing mechanism as outlined above is exemplified as the press-processed product 100, but the press-processed product 100 manufactured by the press processing method according to the present invention is exemplified. However, the present invention is not limited to this, as long as it has the first through hole 11 and the second through hole 12. The present invention can be applied as a pressing method for manufacturing a wide variety of pressed products 100 in which the second through holes 12 are formed by punching.

  The press-processed product 100 is provided in a disk-shaped main body 10, a sensor detection unit 14 extending outward from the main body 10, and a central portion of the main body 10, and protrudes to one surface side of the main body 10. A boss portion 13, a first through hole 11 formed by the inner surface of the boss portion 13, a second through hole 12 drilled around the first through hole 11, and a periphery of the first through hole 11 And a recessed portion 20 that is recessed. Here, the first through hole 11 is for inserting the shaft of the toothed pulley, and the second through hole 12 is for inserting the positioning pin of the toothed pulley.

  The recess 20 does not perform any function with respect to the variable valve timing mechanism. However, as will be described later, the recess 20 is provided to maintain the dimensional accuracy of the first through hole 11. An axis passing through the center of 20 and the center of the first through-hole 11 is arranged to form an angle of 90 ° with respect to an axis passing through the center of the second through-hole 12 and the center of the first through-hole 11. Yes. In other words, the recess 20 is positioned at a right angle to the second through hole 12 with the center of the first through hole 11 as a reference.

  When the second through hole 12 is formed by punching, the inner diameter of the first through hole 11 becomes longer on the axis passing through the center of the second through hole 12 and the center of the first through hole 11, and the second through hole 12 and the first through hole 11 are distorted so that the diameter on the axis perpendicular to the axis passing through the center of the first through hole 11 is shortened. By arranging them at right angles, the formation of the recesses 20 can cause a distortion in the direction opposite to the distortion of the first through holes 11 caused by the formation of the second through holes 12.

  By the way, the press-worked product 100 of this example forms individual workpieces by punching a long rolled steel sheet wound in a coil shape by a single press machine that simultaneously performs a plurality of press work processes. The workpiece is subjected to a plurality of stages of pressing and finally manufactured as a part having a desired shape. A series of pressing processes will be described in detail below with reference to FIGS. Hereinafter, for convenience of explanation, a process of plastically deforming an appropriate part of the workpiece 200 is referred to as “forming process”, and a process of punching and removing an appropriate part of the workpiece 200 is referred to as “punching process”. Processing including all processing that can be performed by a press machine such as “punching” will be referred to as “press processing”.

  First, as shown in FIG. 2, a long rolled steel plate having a constant thickness is punched to form a disk-shaped workpiece 200 (a). Next, the central portion of the workpiece 200 is bulged by molding (b). Here, since it is difficult to bulge the central portion of the workpiece 200 by a single molding process, the central portion of the workpiece 200 is bulged greatly in stages by sequentially performing a plurality of molding processes. Specifically, a large number of molding processes are performed step by step so that the shape of the bulging portion gradually increases from a shape having a large diameter and a low height to a shape having a small diameter and a high height. By these multiple forming processes, the material smoothly flows and collects in the central portion of the workpiece 200.

  After the central portion of the workpiece 200 is sufficiently bulged, a punching process is performed on the central portion of the workpiece 200 to form a primary hole 11a that becomes the first through hole 11, and around the primary hole 11a. The primary boss 13a to be the boss portion 13 is protruded (c). Next, the primary boss 13a is molded and pressed and deformed in the protruding length direction to form a boss portion 13 protruding at a predetermined height on one surface side of the workpiece 200, and the inner diameter has a predetermined dimension. The first through hole 11 is completed (d).

  Next, as shown in FIG. 3, a punching process is performed on the peripheral portion of the workpiece 200 to form the sensor detection unit 14 extending from the main body 20 in a predetermined shape (a). In other words, the outer peripheral portion of the workpiece 200 is punched to form a desired outer shape as the press-processed product 100.

  Next, a bottomed circular recess 20 is formed in the periphery of the first through-hole 11, more specifically, on the outer side of the boss 13 by molding (b). Finally, by punching, the second through hole 12 is formed in the periphery of the first through hole 11, more specifically, at the outer portion of the boss portion 13, and the rolled steel plate is used as the material. Let it be a press-processed product 100 completed through a series of press processing (c).

  Here, the centers of the recesses 20 with respect to the center of the second through hole 12 are at the same distance from the center of the first through hole 11 and at an angle of 90 ° with respect to the center of the first through hole 11. It arrange | positions so that it may space apart. Therefore, the first through hole 11 is distorted by forming the recess 20 by molding. This distortion is generated in the first through hole 11 by the subsequent punching process of the second through hole 12. In the first through-hole 11 of the completed press-worked product 100, the respective strains are partially offset, so that the first through-hole 11 of the completed press-processed product 100 is an intermediate step (see (d) of FIG. 2). The completed dimensional accuracy is satisfactorily maintained without greatly changing. In the first through hole 11, the diameter on the axis passing through the center of the recess 20 and the center of the first through hole 11 is defined as “recess side diameter”, and the center of the second through hole 12 and the center of the first through hole 11 are defined. The diameter on the passing axis is specifically referred to as “second through-hole side diameter”. First, the concave-side diameter and the second through-hole side diameter are perpendicular to each other. In the first through hole 11, the formation of the concave portion 20 causes a distortion such that the diameter of the concave portion becomes longer and the diameter of the second through hole side becomes shorter. Contrary to the distortion caused by the recess 20 described above, a distortion occurs such that the diameter on the recess side becomes shorter and the diameter on the second through-hole side becomes longer. Therefore, although the distortion due to the recess and the distortion due to the second through-hole are not complete, they are partially offset, and the inner diameter of the first through-hole 11 is smaller than when the recess 20 is not provided. Maintained well.

  Further, in this example, the forming direction of the recess 20 (specifically, the pressing direction by the punch, see the arrow A in FIG. 3) is the punching direction of the second through-hole 12 (specifically, the shearing direction by the punch, 3 (see arrow B in FIG. 3), and the distortion due to the recess 20 and the distortion due to the second through-hole 12 occur in the same direction in the front and back direction of the workpiece 200. Therefore, the respective strains are easily canceled out from each other, and the inner diameter of the first through hole 11 is well maintained from this point.

  By the way, in this example, in the workpiece 200 in which the first through hole 11 and the boss portion 13 are formed, the boss portion 13 having a thicker thickness (dimension in the radial direction of the boss portion 13) than the original plate thickness of the workpiece 200. Will be formed. Thereby, the radial rigidity in the boss portion 12 can be sufficiently ensured.

  Further, in the forming process in which the work 200 is simply bent, the work 200 is likely to be broken or cracked. However, the corner portion of the inner surface of the boss portion 13 is set to a thickness of 0. 0 of the workpiece 200 by performing the molding process as described above. It can be a small R shape such as about 5 to 1.0 times. Thereby, the effective length of the part which the axis | shaft penetrated to the 1st through-hole 11 and the inner surface of the 1st through-hole 11 contact can fully be ensured, and the components completed as a wheel sensor were assembled | attached to the axis | shaft. In the state, it is possible to make it difficult for rattling to occur.

  In particular, in this example, the boss portion 13 has a truncated cone shape. Therefore, the material of the end portion of the projecting side of the primary boss 13a is satisfactorily moved to the side opposite to the projecting side, and is filled in the gap of the press die, and the inner surface of the boss portion 13 has a small R shape. A thick boss portion can be formed. Moreover, by making the shape of the boss part 13 into a truncated cone, it is possible to make it difficult for stress concentration to occur between the main body part 10 and the boss part 13, and also from this point, the radial rigidity of the boss part 13 Can be increased.

Next, a press-processed product manufactured by the press processing method according to the present invention (hereinafter referred to as “invention product”) and a press-processed product manufactured by a conventional press processing method that does not form a recess (hereinafter referred to as “conventional product”) The comparison result of is illustrated. The inventive product and the conventional product have the same shape except for the presence or absence of a recess, and specifically have the following shapes.
・ Body thickness: 2.6mm
-Length of boss part (length of first through hole): 6.5 mm
・ Boss diameter: minimum 25mm, maximum 29mm
・ Shape of the connecting part between the boss and main body: R2mm
-Diameter of the first through hole: 22mm
-Diameter of second through hole: 7 mm
-Distance between the center of the first through hole and the center of the second through hole: 19 mm
・ Recess diameter: 5 mm
-Depth of recess: 0.5mm
-Distance between the center of the first through hole and the center of the recess: 19 mm

  In the conventional product, the diameter on the axis passing through the center of the first through hole and the center of the second through hole (hereinafter referred to as “diameter A”) is long over the entire length of the first through hole, and is orthogonal to the diameter A. The diameter in the direction (hereinafter referred to as “diameter B”) is shortened, and the first through hole that should have been formed with high precision roundness is deformed, resulting in a difference of about 0.043 mm between diameter A and diameter B. It was.

  On the other hand, in the product according to the invention, although the first through hole that should have been formed with high accuracy roundness is deformed such that the diameter A becomes longer and the diameter B becomes shorter, the diameter A and the diameter B And a higher dimensional accuracy of the first through hole than the conventional product could be maintained.

It is a top view which shows an example of the press work goods which made the boss | hub part the front side. It is process drawing which shows the press work method which concerns on this invention. It is process drawing which shows the press work method which concerns on this invention. It is a perspective view which shows an example of a press work product.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable valve timing mechanism 2 Pulley with teeth 3 Tooth 4 Axis 5 Positioning pin 6 Press processed product (wheel sensor)
7 1st through-hole 8 2nd through-hole 9 Sensor detection part 10 Main body part 11 1st through-hole 11a Primary hole 12 2nd through-hole 13 Boss part 13a Primary boss 14 Sensor detection part 20 Concave part 100 Press work product 200 Workpiece

Claims (2)

In the press working method for forming the second through hole by punching around the first through hole of the work provided with the first through hole,
The portion around the first through-hole, which is generated when the second through-hole is punched out at a portion separated from the second through-hole at an angle of 90 ° with respect to the center of the first through-hole. A press working method, comprising: pressing a concave portion that causes a strain in the first through hole in a direction opposite to a strain of the first through hole in the same direction as a punching direction of the second through hole .   The press working method according to claim 1, wherein the second through hole is formed by punching after the concave portion is press-molded.

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