JP7348790B2 - Part manufacturing method - Google Patents

Description

The present invention relates to a processing method for forming a protrusion on a metal plate using a press device.

Conventionally, when forming a female thread in a metal plate-like member, a protrusion was formed on the plate material and the inner side of the protrusion was It is common practice to form screw holes in the Burring is also used as a processing method for forming protrusions on thin plates. For example, Patent Document 1 listed below discloses a thin plate burring method in which a cylindrical raised portion is formed on a thin plate by burring.

In the thin plate burring method of Patent Document 1, it is said that sufficient burring height can be obtained even for a thin plate by crushing the target part in advance and performing ejection after the crushing process. ing.

Japanese Patent Application Publication No. 2013-126673

Incidentally, in parts used in parts where particularly strength is required, parts in which screw holes are formed by processing a thick plate (such as a steel plate with a thickness of 3.0 mm or more) are sometimes used. With such a thick plate, it is difficult to perform burring because the deformation resistance of the material increases. Therefore, in the case of thick plate parts, sometimes the thick plate is partially protruded by embossing molding (push molding) using a press machine to form a protrusion, and then tapping is performed to form a screw hole.

However, when performing embossing on a thick plate, due to factors such as increased deformation resistance, the punch will swing if you push the punch into the thick plate once, making it difficult to obtain an extruded shape with a constant thickness with a single extrusion process. is difficult. Furthermore, when embossing a thick plate, there is a problem in that the amount of pushing, processing force, etc. increase in order to push the necessary amount of material into the embossed part.

On the other hand, if the punch diameter is made smaller to reduce the deformation resistance, the absolute volume of material pushed in will decrease, making it difficult to fill the required amount of material into the embossed part (the part that forms the protrusion of the part). becomes. As a result, there are problems such as the material not being sufficiently filled at the base of the protrusion that requires particular strength in the molded part, or the material not flowing well over the entire protrusion, resulting in variations in the diameter and thickness of the protrusion. There is. As described above, when a thick plate is formed by extrusion (embossing), it is difficult to extrude it into a required shape due to the relationship between the thick plate and the punch diameter.

Also, assuming that the protrusion is formed by means such as partially cutting the surface of the thick plate, or by pressing repeatedly with a press device, a constant wall thickness can be obtained. However, there are problems such as increased process and processing costs.

In this way, when forming a protruding part (tap part) in a part molded from a thick plate, the challenge is to stably extrude the protruding part and ensure a stable wall thickness of the protruding part. It had become.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide a method for manufacturing a component that can stably mold the thickness of a protrusion.

Here, conventionally, the inner side of the protrusion was completed as a pilot hole (recess) for a tap by press working, and tapping was performed by inserting a drill into the pilot hole (recess). However, there were problems such as the drill being tilted due to factors such as positional accuracy and hole diameter accuracy during the pressing process, and uneven thickness of the protrusion obtained by pressing, which affected the tool life.

Here, the inventors of the present invention have considered measures for solving the above-mentioned problems. Specifically, a hole (projection) with a diameter one size smaller than the tap pilot hole is formed by press working, and then the tap pilot hole is formed by passing through the projection by cutting, and then the tap pilot hole is formed. We considered performing tapping on the In this way, a stable hole diameter can be obtained by cutting.

However, as mentioned above, the extrusion of a thick plate is determined by the positional relationship and relative size of the punch to be pushed in and the lower die that receives it, so the smaller the punch diameter, the less material is pushed in, which is disadvantageous for forming. becomes.

The inventors of the present invention have further investigated a method that can stably press material into an embossed part by pressing with a small-diameter punch. As a result, if preliminary pressing is performed using a punch with a diameter slightly larger than the punch used during extrusion molding, the material (meat) can be efficiently flowed to the part where the protrusion will be formed (embossed part). The following findings were obtained. Specifically, by using a punch with a larger diameter than the punch used during extrusion molding to generate plastic flow in the material, more thickness can be extruded when the material is subsequently molded with a smaller diameter punch. We found that it is possible to do so.

To explain in more detail, if preliminary pressing is performed using a punch with a larger diameter than the punch used during extrusion molding, the opening edge of the embossed part will have a tendency to bend so that the molding material will fit in, and the opening edge will be formed. Extrusion molding can be carried out in a state where the materials are familiar. In other words, it is possible to generate a trigger for conforming to the lower die of the plank, and to press sufficient material into the base of the protrusion of the part to form the part.

As a result, during extrusion molding, there is no gap at the opening edge of the embossed part (the base of the protrusion of the part), a gap on the side of the punch (inner peripheral surface of the protrusion), or a corner of the embossed part (the base of the protrusion of the part). It is possible to reduce the gap at the tip of the part. As a result, it is possible to reduce unevenness in the thickness of the component or insufficient thickness at the root or tip of the protrusion, thereby reducing concerns about a decrease in the strength of the component.

The method for manufacturing a component of the present invention provided based on the above-mentioned knowledge is a method for manufacturing a component in which a protrusion is formed on a thick plate by push molding using a press device having a lower mold and a punch, the method comprising: The method includes a pre-pressing step of pre-pressing the thick plate with a first punch, and an extrusion-molding step of extruding the thick plate with a second punch to form the protrusion after the pre-pressing step, The outer diameter of the first punch is larger than the outer diameter of the second punch.

According to the method for manufacturing parts of the present invention, during extrusion molding, there is no gap in the opening edge of the embossed part (the base of the protruding part of the part), a gap in the punch side surface (inner peripheral surface of the protruding part), or embossed molding. It is possible to reduce gaps at the corners of the parts (the tips of the protruding parts of the parts). As a result, it becomes possible to machine screw holes while securing machining allowance through cutting, etc., reducing uneven thickness of parts or insufficient wall thickness at the base or tip of protrusions, which reduces the strength of parts. concerns can be reduced.

As described above, according to the component manufacturing method of the present invention, a large volume of molding material is extruded into the embossed part to stabilize the shape of the protruding part and to ensure machining allowance when forming a tapped hole or tapping. The quality of parts can be stabilized.

Furthermore, according to the method for manufacturing parts of the present invention, the material can be processed through a preliminary pressing step and a single extrusion molding step, without having to perform multiple extrusion molding steps to extrude the material into the embossed part. It is possible to do this without requiring a significant increase in the number of steps. Further, according to the component manufacturing method of the present invention, it is possible to reduce the stroke amount of the punch and the processing force in the extrusion molding process.

Further, in the component manufacturing method of the present invention, a C-face forming portion serving as a chamfered portion of the first punch is provided at an end of the first punch, and in the preliminary pressing step, the It is preferable that a C-plane is formed on the part.

According to the above-described configuration, the preliminary pressing process can also be performed as the process of forming the C-plane. As a result, according to the component manufacturing method of the present invention, it is not necessary to provide a separate step of forming the C-plane, and the process can be simplified.

Furthermore, in the method for manufacturing a component of the present invention, the extrusion molding step forms the protrusion that protrudes in the extrusion direction on the component, and a hole is formed inside the protrusion. A C-face forming part, which is a chamfered part of the first punch, is provided at the end of the first punch, and a C-face forming part, which is a chamfered part of the first punch, is provided at a part that becomes the opening edge of the hole in the preliminary pressing step. It is desirable that the outer diameter of the first punch is large enough to include the C-plane of the hole.

According to the above configuration, the molding material can be efficiently blended into the opening edge of the embossed part in the preliminary pressing step.

According to the component manufacturing method of the present invention, the thickness of the protrusion can be formed stably.

FIG. 1 is a schematic diagram of a press device used in an embodiment of the present invention. It is a figure showing an example of parts manufactured by the manufacturing method of the present invention. FIG. 2 is a diagram showing a preliminary pressing process performed using the press device of FIG. 1. FIG. 2 is a diagram showing an extrusion molding process performed using the press apparatus of FIG. 1. FIG. It is a figure which shows the tapping process performed after extrusion molding. FIG. 2 is a diagram showing a main part of an embossing section of the press device shown in FIG. 1. FIG. It is a figure which shows the modification of the press apparatus of FIG. 8 is a diagram showing an extrusion molding process performed by the press apparatus of FIG. 7. FIG.

Embodiments of the present invention will be described below with reference to the drawings. In the component manufacturing method of the present invention, a press apparatus 10 shown in FIG. 1 is used.

In this embodiment, a method for manufacturing a rear suspension plate of a vehicle as a part P will be explained as a specific example. As shown in FIGS. 2(a) and 2(b), the part P is a part in which a protrusion Pc is formed on a thick steel plate (8.0 mm in this embodiment), and from one side to the other. A screw hole Pb is formed so as to penetrate through the surface.

Note that the component manufacturing method and press apparatus of the present invention are not limited to manufacturing a rear suspension plate as a component, but can be widely applied to components in which a protrusion is formed on a thick plate.

Note that in this specification, a "thick plate" refers to a metal material such as a steel plate formed into a plate shape, and has a thickness of 3.0 mm or more.

As shown in FIG. 2(b), the part P is a steel plate material (hereinafter sometimes simply referred to as a "thick plate" or "workpiece W") with a thickness D1 (8.0 mm in this embodiment). ) is manufactured by processing. Further, as shown in FIG. 2(c), the screw hole Pb of the completed component P has an inner diameter D3 (10.8 mm in this embodiment).

As shown in FIG. 2(a), the component P has a plate-like portion Pa formed with a protrusion Pc. As shown in FIG. 2(b), the protrusion Pc is formed on one of the front and back surfaces of the component P.

As shown in FIG. 2(c), the protruding portion Pc has a predetermined height D4 (4.0 mm in this embodiment) from the plate-like portion Pa. A screw hole Pb is formed in the inner peripheral surface of the protrusion Pc. Further, a C surface Pe, which is a chamfered portion, is formed on the surface opposite to the side on which the protruding portion Pc is formed, and at a portion that becomes the opening edge of the screw hole Pb.

In addition, in the following description, in the part P or the work W, the surface on the side where the C surface Pe is formed may be described as "upper surface F1". Further, the surface opposite to the upper surface F1 (the surface on which the protrusion Pc is formed) may be described as a "lower surface F2" or a "protrusion forming surface F2."

The press device 10 is for performing press processing such as extrusion molding and shear processing on a work W (molding material) such as a steel plate material.

The press device 10 includes a slider, a cylinder, a guide post, etc., which are not shown. Further, as shown in FIG. 1, the press device 10 includes a punch 13, a lower mold 20, and a pressing member 12. The press device 10 is provided with a first punch 30 (first punch) and a second punch 40 (second punch) as the punches 13.

In addition, in the following description, the first punch 30 and the second punch 40 may be collectively referred to simply as "punch 13". Further, the stroke direction (pressing direction) of the punch 13 may be simply described as "pressing direction X" for explanation.

As shown in FIG. 1, the lower die 20 is provided with an embossed part 22 for forming the protrusion Pc of the component P. The embossed part 22 is formed as a concave portion of the lower die 20.

As shown in FIG. 3A, the inner diameter of the embossed portion 22 is set to a size corresponding to the outer diameter D2 of the protrusion Pc (inner diameter D2, 16.0 mm in this embodiment). Further, the embossed portion 22 has a depth D4 (4.0 mm in this embodiment) corresponding to the height D4 of the protrusion Pc. The opening edge (corner portion 24) of the embossed portion 22 is rounded. In the following description, the inner circumferential surface of the embossed part 22 may be referred to as a "vertical wall portion 25" and the portion that becomes the bottom surface may be referred to as a "bottom portion 23."

The first punch 30 (first punch) is provided to perform a preliminary pressing process. As shown in FIG. 3(a), the first punch 30 is formed with a seat surface 32 that presses the workpiece W substantially orthogonally. Further, the first punch 30 is provided with a C-surface forming portion 34 that is a chamfered portion so as to surround the seat surface 32. The C-plane forming section 34 is provided to form the C-plane Pe of the component P.

The second punch 40 (second punch) is provided for performing an extrusion molding process. More specifically, the second punch 40 is provided to push the workpiece W into the embossing molding section 22 and form the protrusion Pc on the workpiece W. As shown in FIG. 4A, the second punch 40 has an outer diameter D6 (9.8 mm in this embodiment) that is larger than the thickness of the workpiece W (8.0 mm).

Here, the relationship between the radial sizes of the first punch 30 and the second punch 40 will be explained. The outer diameter D5 (14.0 mm in this embodiment) of the first punch 30 is larger than the outer diameter D6 (9.8 mm in this embodiment) of the second punch 40 (D5>D6). Further, the outer diameter D5 of the first punch 30 is a size including the outer diameter of the C surface Pe formed on the part P (size of the screw hole Pb + size of the chamfered part (C surface)), and It is smaller than the inner diameter D2 (16.0 mm in this embodiment) of the embossed part 22. To explain more specifically, the hole diameter (inner diameter D3) at the time of completion of the part P is set as the target dimension, and the outer diameter D6 of the second punch 40 is set as a size that takes into account the tapped hole and the machining allowance for tapping. The outer diameter D5 of the first punch 30 is set as a diameter that takes into consideration the formation of the C-plane Pe.

Therefore, when the first punch 30 presses the work W and performs preliminary pressing, the material (work W) is bent so that it gets caught on the opening edge (corner 24) of the embossed part 22, and the corner 24 is bent. The materials become familiar. That is, before the main processing (extrusion molding step), a large diameter punch (first punch 30) can be used to once generate plastic flow in the material (preliminary pressing). Thereby, in the extrusion molding process to be performed later, a larger volume of material can be extruded into the embossed part 22 compared to the case where preliminary pressing is not performed.

Next, a preliminary pressing process and an extrusion molding process performed using the press device 10 will be explained.

<Pre-pressing process>
In the preliminary pressing process, the C surface Pe of the workpiece W, which is required for tapping, is formed in advance, and the diameter of the punch (first punch 30) at that time is increased to improve the shape of the material (workpiece W). A trigger for familiarization to the lower mold 20 is generated.

The preliminary pressing step is performed by pressing the workpiece W, which is placed at the processing position of the press device 10 and held by the pressing member 12, by a predetermined amount with the first punch 30. Specifically, as shown in FIGS. 3(a) and 3(b), the first punch 30 is inserted into a predetermined position with respect to the workpiece W which is sandwiched and positioned between the lower die 20 and the holding member 12. It is stroked by a distance (a stroke amount that forms C surface Pe on the workpiece W) and pressed.

As a result, a portion that becomes the C surface Pe is formed on the workpiece W (see FIG. 4(a)), and the lower surface F2 (protrusion forming surface F2) of the workpiece W is pressed so as to fit into the corner 24. (See FIG. 6(a)). That is, by pressing the upper surface F1 of the workpiece W with the seating surface 32 of the first punch 30 having a large area (an area close to the area of the opening area of the embossed part 22), the lower surface F1 of the workpiece W is pressed. F2 can efficiently contact the corner portion 24 and generate plastic fluidity in the workpiece W.

<Extrusion molding process>
After the preliminary pressing step, an extrusion molding step is performed. As shown in FIG. 4(b), in the extrusion molding process, the second punch 40 is stroked downward to extrude the workpiece W so as to follow the shape of the embossed part 22. As described above, in the pre-pressing process, the workpiece W is in a state where it fits into the corner part 24 (see FIG. 6(a)), so when the workpiece W is extruded in the extrusion process, the embossed part 22 The material flows efficiently toward the corner 26 (see FIG. 6(b)). As a result, it is possible to suppress the occurrence of the problem that the material is not filled in the vicinity of the corner portion 24 or that the material is not sufficiently pushed into the vertical wall portion 25.

As shown in FIG. 5A, by the extrusion molding process, a protrusion Pc is formed on the workpiece W (thick plate), and a hole Pf is formed inside the protrusion Pc. After the extrusion molding process, the workpiece W is tapped. Specifically, the hole portion Pf is penetrated using a machine tool such as a machining center, and then the threaded hole Pb is formed by tapping. Through these steps, as shown in FIG. 5(b), a screw hole Pb having an inner diameter D3 is formed in the inner circumferential surface of the protrusion Pc.

As described above, according to the component manufacturing method of the present invention, the material (workpiece W) that has caused the material to become familiar to the lower die 20 in the preliminary pressing process is By performing secondary processing (extrusion processing) on the diameter), it is possible to obtain appropriate conformability to the lower mold. Furthermore, according to the method for manufacturing parts of the present invention, the stroke amount and processing pressure during extrusion molding can be reduced.

As described above, according to the component manufacturing method of the present invention, even if the second punch 40 has a small diameter, a large volume of material is extruded into the embossed part 22, the shape of the protruding part Pc is stabilized, and the tapped hole is The quality of the part P can be stabilized by ensuring machining allowance when forming (when penetrating the hole Pf) or tapping.

Further, according to the method for manufacturing parts of the present invention, the material is processed through a preliminary pressing step and a single extrusion molding step, without performing multiple extrusion molding steps to extrude the material into the embossed part 22. , and does not require a significant increase in the number of steps.

Through the steps described above, a part P as shown in FIG. 2 is manufactured. As described above, according to the manufacturing method of the present invention, the protruding part Pc (rising part) of the screw hole Pb is formed by press working without performing processing such as cutting the surface of the thick plate to cut out the protruding part. can do. Furthermore, the workpiece W can be efficiently processed in the extrusion molding process by using the process of forming the C-plane Pe as a preliminary pressing process. As a result, the protrusion Pc of the component P can be efficiently formed without requiring an excessively large number of steps. Furthermore, it is possible to suppress the occurrence of problems such as the strength of the component P being reduced because the material is not sufficiently filled in the base portion (neck portion Pd) and the tip portion of the protruding portion Pc.

<Modified example>
Next, a modification of the present invention will be explained. In the component manufacturing method of the present invention, a lower mold 50 described below can be used instead of the lower mold 20.

As shown in FIG. 7A, the lower die 50 is provided with an embossed portion 52 that is a concave portion for forming the protrusion Pc. Furthermore, a step portion 60 (bulging portion) formed to bulge toward the punch 13 is provided on the bottom surface portion 53 of the embossed portion 52 .

As shown in FIG. 7A, the stepped portion 60 is provided approximately at the center of the bottom portion 53 of the embossed portion 52, and has a generally circular upper surface 62 in plan view. As shown in FIG. 7(b), the height D7 of the stepped portion 60 is less than half the distance (this modification In this case, the depth is 2.0 mm, which is half of the depth D4.

Further, as shown in FIG. 7B, an inclined portion 64 is provided between the upper surface 62 of the stepped portion 60 and the bottom surface portion 53 as a surface inclined toward the bottom surface portion 53. The slope angle θ of the slope portion 64 forms an angle with respect to the axis L of the punch 13. In this modification, the inclination angle θ of the inclination portion 64 (the angle with respect to the axis L of the punch 13) is approximately 45 degrees.

When extrusion molding is performed using the lower die 50, in addition to the flow of the material due to the pushing of the second punch 40, the shape of the stepped portion 60 formed in the lower die 50 can promote the flow of the material. As a result, the thickness of the protruding portion Pc can be increased more efficiently.

As shown in FIGS. 8(a) and 8(b), when the workpiece W is pressed against the lower die 50 by the second punch 40, there is a gap between the seating surface 42 of the second punch 40 and the upper surface 62 of the stepped portion 60. The material sandwiched between is pushed along the inclined portion 64 toward the corner 56 of the embossed portion 52 (towards the outside in the radial direction of the embossed portion 52). Thereby, the material is filled toward the corner 54, vertical wall 55, corner 56, etc. of the embossed part 52, and the deviation in the thickness of the protrusion Pc of the component P can be reduced.

As mentioned above, in the past, when forming a thick plate by indentation (embossing), it was difficult to extrude it to the required shape due to the relationship between the thick plate and the punch diameter, but with the manufacturing method of the present invention, , it is possible to extrude a thick plate into the required shape without requiring an excessive increase in the number of steps.

As a result, according to the method for manufacturing parts of the present invention, the material is efficiently flowed toward the periphery of the embossed part 22 to form the protruding part of the part, and the uneven thickness of the protruding part or It is possible to reduce the problem of insufficient wall thickness at the base and tip of the protrusion, thereby reducing concerns about a decrease in the strength of the component.

The present invention can be suitably employed as a method for manufacturing parts by extrusion molding a thick plate using a press machine.

10 Press device 13 Punch 20 Lower die 22 Embossed part 23 Bottom part 24 Corner part 30 First punch (first punch)
40 Second Punch (Second Punch)
50 Lower die 52 Embossed part 53 Bottom part D5 Outer diameter D6 Outer diameter P Part Pc Projection part W Work (thick plate)

Claims (1)

A method for manufacturing a part in which a protrusion is formed on a thick plate by push molding using a press device having a lower mold and a punch, the method comprising:
a preliminary pressing step of preliminary pressing the thick plate with a first punch;
After the preliminary pressing step, an extrusion molding step of extruding the thick plate with a second punch to form the protrusion,
The outer diameter of the first punch is larger than the outer diameter of the second punch,
A C-plane forming portion serving as a chamfer of the first punch is provided at an end of the first punch,
A method for manufacturing a component, characterized in that in the preliminary pressing step, a C-face is formed on the component .

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