JP3546647B2 - Press molded part, molding method and molding apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a press-formed part, a method of forming the same, and a forming apparatus, and more particularly to press-forming a corner of a drum-shaped part.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in order to manufacture a drum-shaped component, a processing method of drawing a plate-shaped material into a cylindrical shape by drawing is used. For example, as shown in FIG. 5, such a drum-shaped component is used as a stepped drum D of a multi-plate clutch or a multi-plate brake as a friction engagement device such as an automatic transmission. In this example, the small-diameter cylindrical portion Ds of the stepped drum D is a cylinder on which the piston P of the hydraulic servo slides, and the large-diameter cylindrical portion Dl is a support portion of the friction engagement element F. .
[0003]
By the way, the corner of the bent portion L connecting the cylindrical portion Ds and the plate-shaped portion Df of such a drum-shaped component has a certain degree of roundness (in terms of a radius when viewed in cross section, Since it is generally called a radius (R), it is inevitable that a rounded corner portion is referred to as a corner radius throughout this specification. It is difficult to make the corner radius equal to or less than the sheet thickness by ordinary press molding.
[0004]
[Problems to be solved by the invention]
Such a corner radius may not be preferable depending on the use form of the component. In particular, when the corner radius is one end of the cylinder as in the above example, if the seal portion of the piston P is applied to the corner radius, leakage of servo hydraulic pressure occurs. Therefore, in such a case, the corner radius is outside the sliding range of the seal portion, and an extra shaft length is required for the drum D, which hinders the compactness of the apparatus. Conversely, if the corner radius can be reduced, the stroke amount of the piston P can be effectively secured within the limited space.
[0005]
Therefore, when a work W formed in advance by drawing and forming a drum-shaped part as shown in FIG. 6A is press-formed, the side to be the plate-shaped portion Df is flattened as shown in FIG. The pressing punch a compresses the die B with the die b to reduce the outer corner R of the boundary between the cylindrical part Dl and the plate part Df. However, in the compression by the flat pressing punch a, there is a limit in obtaining a corner radius R approximately equal to the thickness of the work W. Further, even if the compressive force of the punch a is increased in order to further reduce the corner radius, the material spreads to the side opposite to the corner portion, and the corner radius cannot be sufficiently reduced. Therefore, in order to prevent the flesh of the material from escaping in the outer diameter direction, it is not possible to consider a method of restricting the outer peripheral side with a die c as shown in FIG. Since the load between the shape part Df and the die c is increased, there is a concern that the die c may be cracked or deformed at the time of dispensing due to the work W sticking to the die c.
[0006]
Accordingly, a first object of the present invention is to provide a press-formed product having a shape in which a small inner radius can be obtained over the entire circumference .
[0007]
A second object of the present invention is to reduce the size of the automatic transmission by using a press-formed product having the small corner radius.
[0008]
Next, a third object of the present invention is to provide a method for molding the molded part as described above.
[0009]
A fourth object of the present invention is to provide an apparatus used for carrying out the molding method.
[0010]
Further, a fifth object of the present invention is to provide a punch shape which promotes formation of a small corner radius while improving the durability of the punch and the mold release performance in the above-mentioned molding apparatus.
[0011]
[Means for Solving the Problems]
In order to achieve the first object, the present invention provides a press-formed part having a tubular portion and a plate-shaped portion, in the vicinity of an outer corner side bent portion of an inner diameter side bent portion where the tubular portion and the plate-shaped portion are connected to each other. A groove formed by pressing around the corner portion is formed on the plate-shaped portion located on an extension of the outer peripheral surface of the cylindrical portion .
[0012]
In order to achieve the second object, the press-formed part is a drum-shaped member used for a friction engagement device of an automatic transmission.
[0013]
According to a third aspect of the present invention, there is provided a method of forming a press-formed part using a punch and a die, wherein the plate-shaped part connected to the cylindrical part is supported while supporting the inner peripheral side of the cylindrical part of the formed part by the punch. During pressing, in which the cylindrical part and the plate-shaped part are connected to each other, the plate-shaped part located on the extension of the outer peripheral surface of the cylindrical part in the vicinity of the outer corner of the bent part on the inner diameter side In addition, a groove is formed around the corner portion by pressing the punch.
[0014]
In order to achieve the fourth object, in an apparatus for forming a press-formed part by a punch and a die, an inner surface of the punched part facing a die is connected to a cylindrical part and a plate part of the formed part. On the plate-like portion located on an extension of the outer peripheral surface of the cylindrical portion near the outer corner on the outer corner side of the bent portion, a ridge for forming a groove around the corner is provided.
[0015]
Furthermore, in order to achieve the fifth object, the ridge is configured to have a trapezoidal cross section with the side facing the die as the upper bottom.
[0016]
Function and effect of the present invention
In the press-formed part according to claim 1, which adopts the above configuration, a groove for reducing the inside radius of the press-formed part by plastically flowing material of the material to the inner diameter side of the plate-shaped part is formed on the plate surface side of the corner part. Therefore, while obtaining a small corner radius by forming the groove, it is possible to realize a form in which the groove does not hinder the use of the inner surface on the cylindrical portion side. Also, by forming the groove on the plate-shaped portion located on the extension of the outer peripheral surface of the cylindrical portion, the material meat is effectively plastically flowed into the inner-diameter corner of the plate-shaped portion to reduce the corner radius. However, a component form that does not impair the component strength can be obtained. Further, by forming the groove around the corner portion, the corner radius of the press-formed part can be reduced over the entire circumference.
[0017]
Further, according to the configuration of the second aspect , since the corner radius is small, a piston stroke of a clutch or a brake, which is a friction engagement device of the automatic transmission, can be lengthened in a limited space. As a result, the axial dimension of the automatic transmission can be reduced.
[0018]
Next, according to the forming method of the third aspect , since the groove is formed near the inner diameter side corner portion where the cylindrical portion and the plate-shaped portion of the press-formed part are connected, the material of the material is formed into the corner portion at the time of groove formation. Plastic flow can be caused toward the inner diameter side of the groove toward the groove, and a press-formed part having a small corner radius can be obtained.
[0019]
Next, according to the molding apparatus of the fourth aspect , by providing the groove with a groove forming protrusion on the punch, the protrusion is formed near the inner diameter side corner portion where the cylindrical portion and the plate portion of the press-formed part are connected. When molding, it is possible not only to prevent the flesh of the material from flowing to the outer diameter side of the plate-shaped portion, but also to positively plastically flow the corner portion on the inner diameter side, and to provide a groove forming ridge on the punch By itself, the corner radius of the press-formed part can be reduced.
[0020]
Further, according to the configuration of the fifth aspect, the inclination of the trapezoidal side surface of the ridge on the side of the corner promotes the extruding of the meat in the direction of the corner, and the flow of the meat is improved. It can be even smaller. In addition, the inclination of both sides of the trapezoidal side surface of the ridge makes it easier to remove the punch, and facilitates the dispensing of the formed part after processing. Further, since the upper base of the trapezoid of the ridge is flat, the durability of the ridge of the punch is improved.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an axial cross section of a press-formed part according to an embodiment. This part is composed of three cylindrical tubular parts 11, 12, 13 and three disk-shaped plate parts 14, 15. , 16 and a stepped drum-shaped member 1 having a conical portion 17 and having a uniform cross section in the circumferential direction.
[0022]
According to the present invention, a groove 18 formed by pressing is formed on the plate-shaped portion 14 near the outer corner side corner R of the bent portion L where the cylindrical portion 11 and the plate-shaped portion 14 of the drum-shaped member 1 are mutually connected. The groove 18 is formed around the corner R so as to be located on an extension of the outer peripheral surface S of the cylindrical portion 11.
[0023]
As shown in FIG. 2, the drum-shaped member 1 as a press-formed part according to this embodiment is used as a hydraulic servo cylinder in a friction engagement device of an automatic transmission, for example. In this use mode, the plate-like portion 14 of the drum-like member 1 is formed with spline peaks between the grooves by a subsequent groove cutting process, and is fitted into the inner peripheral spline groove 21 of the transmission case 2 so as to prevent rotation. Is axially stopped by the drum-shaped member 3. A piston 4 having a similar shape is axially movably fitted on the inner periphery of the drum-shaped member 1, and O-rings 41 and 42 disposed near both ends in the axial direction of the piston 4 allow the drum-shaped member 1 to be moved. Is prevented from leaking between the inner periphery of the cylindrical portion of FIG.
[0024]
As is well known, the piston 4 compresses the return spring 5 from the initial retracted position (the position shown) due to the load of the return spring 5 by supplying hydraulic pressure between the piston 4 and the cylinder composed of the drum-shaped member 1. While being pushed out in the axial direction (to the right in the example of the drawing) and pressing the brake plate 6 with the tip of the piston 4, the frictional engagement device is brought into engagement. With the movement, the O-ring 41 fitted to the distal end of the piston 4 also slides toward the distal end of the cylindrical portion 11 of the drum-shaped member 1. The limit of the engagement direction of the piston stroke is just before the O-ring 41 reaches the corner radius of the drum-shaped member 1. This is because when the O-ring 41 reaches the corner radius, oil leakage may occur.
[0025]
Thus, according to the frictional engagement device of this embodiment, since the corner radius is substantially reduced to about half of the plate thickness, the same piston stroke is obtained as compared with the conventional case where the corner radius is greater than the plate thickness. However, the axial dimension of the cylinder composed of the drum-shaped member 1 can be shortened accordingly. This contributes to a reduction in weight and size by reducing the axial dimension of the entire automatic transmission. Moreover, since the groove 18 for reducing the corner radius R over the entire circumference is located on the plate surface side of the corner portion, the groove 18 serves as the piston sliding surface on the cylindrical portion side inner surface without deteriorating the component strength. A form that does not hinder use can be realized.
[0026]
Next, FIG. 3 shows an apparatus for forming the press-formed part. In the figure, the left half shows the state before molding, and the right half shows the state after molding. This device is a device for forming a press-formed part W by a groove forming punch 7 and a die 8. The lower holder 90 holding the die 8 holds the work W, and is used for lowering and discharging for forming. A pad 92 supported by a pad spring 91 so as to be able to ascend, a lifter 93 arranged so as to surround the outer periphery thereof, and similarly movable up and down, and a plate 94 arranged so as to further surround the outer periphery, and a pressing plate 94 And a die 8 which is fixed by pressing.
[0027]
On the other hand, a punch 101 that fits on the inner peripheral side of the work W is fixed to the upper plate 100 via a backing plate 102, and the groove forming punch 7 is guided by the knockout pin 103 so as to surround the outer periphery, and On the other hand, it is arranged to be supported by the knockout 104 so as to be able to move up and down. The groove forming punch 7 is provided with a groove forming protrusion 71. The ridge 71 has a trapezoidal cross section with the side facing the die 8 as the upper bottom. In the drawings, reference numeral 95 indicates a guide bush, 96 indicates a lifter pin, 97 indicates a cushion pin, 98 indicates a spool retainer, 105 indicates a guide post, 106 indicates an upper holder, and 107 indicates an adapter plate.
[0028]
Lastly, a molding method will be described with reference to FIGS. As shown in FIG. 3, in this embodiment, the material W has another portion already formed by drawing, and only the plate-shaped portion 14 remains at a large corner radius. The workpiece W in this state is centered and positioned on the pad 92 with the processing portion facing upward.
[0029]
When the elevator is lowered, the groove forming punch 7 is lowered as shown in FIG. 4, and accordingly, the punch 101 is also lowered and fitted to the circumference of the work W. The state before the molding is shown in FIG. 4A, and the work W is supported by the punch 101, the die 8, and the lifter 93 to support the cylindrical portion 11 and the plate-like portion 15 and is immovably restrained.
[0030]
Next, molding starts, and the groove forming punch 7 is lowered as shown in FIG. As a result, before the lower surface of the plate-shaped portion 14 has not yet contacted the die 8, the ridge 71 starts to bite into the work W, and the material of the material radially inward of the ridge 71 is directed toward the corner portion ( Plastic flow in the direction of the arrow). In this case, the radial position of the ridge 71 is such that the material can be effectively extruded radially inward from the ridge 71, and the position of the workpiece W is as close as possible to the corners in terms of processing. It is on an extension of the outer peripheral surface of the shape portion 11.
[0031]
Further, as the compression by the groove forming punch 7 progresses, as shown in FIG. 4 (C), the lower surface of the plate-shaped portion 14 comes into contact with the die 8 and a slight compression acts on the entire plate surface. To end. Thus, a corner radius of about half the thickness of the work can be formed at the bent portion of the work W. In this step, the corner radius R ′ at the inner corner side of the bent portion is also formed in accordance with the chamfer of the inner peripheral upper corner of the die 8. In this case, since the plastic flow of the material in the direction of the corner portion has already been sufficiently performed according to the present invention, it is substantially unnecessary to compress the entire surface of the plate-like portion 14 as in the related art, so that the compressive load is reduced. Need not be particularly large.
[0032]
When the molding is completed in this way, the elevator is raised toward the position shown in the left half of FIG. At this time, the punch 101 comes out of the work W which was initially held by the groove forming punch 7, and then the punch 7 which comes off easily comes off due to the inclination of both sides of the trapezoidal side surface of the ridge 71 of the groove forming punch 7. Thereafter, the work W is paid out by raising the pad 92 as in the conventional case.
[0033]
As described above in detail, according to the molding apparatus and the molding method using the same, the groove forming punch 7 is provided with the groove forming protrusions 71, so that the protrusions 71 and the cylindrical portion 11 of the press-formed part 1 are provided. When the groove 18 is formed in the vicinity of the corner where the plate-shaped portion 14 is connected, not only can the material of the material be prevented from flowing to the outer diameter side of the plate-shaped portion 14, but also the inside of the plate 14 can be positively moved toward the corner portion. By simply providing the groove 7 on the punch 7, the corner radius of the press-formed part can be reduced. Further, the inclination of the trapezoidal side surface of the ridge 71 on the corner side promotes the extruding of the meat of the material in the corner direction and improves the flow of the meat, so that the corner radius can be further reduced. Also, the inclination of the trapezoidal sides of the ridge 71 on both sides facilitates the removal of the punch 7 and facilitates the dispensing of the formed part after processing. Further, since the upper base of the trapezoid of the ridge 71 is flat, the durability of the ridge of the punch 7 is improved.
[0034]
As described above, the present invention has been described in detail based on one embodiment. However, the present invention is not limited to only the disclosed contents of the above-described embodiment, and various detailed configurations within the scope of the claims are described. It is needless to say that the present invention can be implemented by changing.
[Brief description of the drawings]
FIG. 1 is an axial sectional view showing one embodiment of a press-formed part to which the present invention is applied.
FIG. 2 is a partial cross-sectional view in the axial direction showing a state in which the press-formed part is assembled into an automatic transmission.
FIG. 3 is a longitudinal sectional view showing the configuration of a molding apparatus to which the present invention is applied, including its operation.
FIG. 4 is a process explanatory diagram showing the forming method of the present invention step by step.
FIG. 5 is an axial sectional view showing a drum of a friction engagement device of a conventional automatic transmission and its related parts.
FIG. 6 is a processing explanatory view showing a conventional method for forming a corner portion of a press-formed part.
FIG. 7 is a processing explanatory view showing another method of forming a corner portion of a conventional press-formed part.
[Explanation of symbols]
1 Drum-shaped members (press-formed parts)
7 Groove forming punch 8 Die 11 Cylindrical portion 14 Plate portion 18 Groove 71 Convex ridge L Bend R Corner radius (corner)

Claims (5)

In a press-formed part having a cylindrical portion and a plate-shaped portion, the plate-shaped portion located on an extension of the outer peripheral surface of the cylindrical portion near the outer corner at the inner-side bent portion where the cylindrical portion and the plate-shaped portion are interconnected. A press-formed part, characterized in that a groove formed by pressing around a corner portion is formed on the side of the portion . The press molded part is a drum-shaped member for use in friction engagement device of the automatic transmission, 1 Symbol mounting press molding parts claims. In a method of forming a press-formed part by a punch and a die, a press is formed by pressing a plate-shaped part connected to a cylindrical part against a die with a punch while supporting the inner peripheral side of the cylindrical part of the molded part by a punch. Occasionally, the cylindrical portion and the plate-shaped portion are connected to each other, and the plate-shaped portion located on the extension line of the cylindrical portion outer peripheral surface near the outer corner-side corner portion of the inner radius side bent portion is surrounded by the punch by press contact with the corner portion. A forming method characterized by forming a groove. In an apparatus for forming a press-formed part by a punch and a die, a cylindrical part near an outer corner side of an inner diameter bent part where a cylindrical part and a plate part of the molded part are connected to each other on a surface facing a die of a punch. A molding device, characterized in that a ridge for forming a groove around a corner portion is provided on a plate-shaped portion side located on an extension of an outer peripheral surface of the portion . The molding device according to claim 4 , wherein the ridge has a trapezoidal cross-section having a side facing the die as an upper bottom.

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