JP7512959B2 - Press-fitting device and press-fitting method - Google Patents

Description

The present invention relates to a press-fitting device and a press-fitting method.

Conventionally, press-fitting devices and press-fitting methods for pressing an axial part into a press-fit hole in a workpiece are known. For example, in the press-fitting device disclosed in Patent Document 1, a press-fitting means (hydraulic cylinder) is floating-connected to an attachment member attached to a positioning means such as a robot hand or manipulator. Specifically, the press-fitting means is connected to the attachment member via a spring so that it can move up and down or swing. It is described that this prevents the press-fitting reaction force from acting on the positioning means.

JP 2006-116669 A

For example, when a workpiece to be pressed into a casting is supported by a receiving jig on the casting surface, not the machined surface, or when the workpiece is pressed into a press-fit hole that is positioned away from the center of gravity of the workpiece, the workpiece may tilt. If an axial part is pressed into a tilted workpiece by applying a press-fit load that is greater than necessary, there is a risk of insufficient press-fitting or the workpiece cracking. There is also the problem that the press-fit actuator requires more energy than necessary. The conventional technology of Patent Document 1 does not take into consideration measures against such tilting of the workpiece to be pressed into.

The present invention was created in light of these points, and its purpose is to provide a press-fitting device and press-fitting method that can perform appropriate press-fitting without applying more force than necessary, even if the workpiece being pressed into is tilted.

The press-fitting device of the present invention is a device for pressing a shaft-shaped part (90) into a press-fit hole (88) formed inside a container-shaped housing (80) that has a pressing end face (83) on the periphery of an opening (82) and a press-fit hole (88) formed inside the opening as a workpiece to be pressed in. This press-fitting device includes a receiving jig (40), a housing presser (30), a punch (20), a support post (50), a pull rod (61), and a pull-down biasing member (62) .

The receiving jig receives the housing by abutting from below against the receiving surface (84, 85) provided on the opposite side of the housing opening. The housing presser is biased downward by the pressing member (37) and abuts against the pressing end surface of the housing, pressing the housing against the receiving jig.

The punch, while holding the shaft-shaped part, descends toward the press-fit hole and applies a press-fit load. The support post supports the part directly below the press-fit hole (45) located directly below the press-fit hole on the opposite side of the receiving jig from the housing. The pull rod passes through an insertion hole (56) formed along the axis of the support post and is connected to the part directly below the press-fit hole of the receiving jig. The pull-down biasing member biases the pull rod downward so that the part directly below the press-fit hole abuts against the top (55) of the support post.

When the housing clamp comes into contact with the clamping end face of the housing, the receiving jig can float so that it tilts with the point directly below the press-fit hole as a fulcrum.

With the housing clamp abutting the clamp end face, the receiving jig floats so that it tilts with the point directly below the press-fit hole as a fulcrum, correcting the position of the workpiece being pressed into a horizontal position. This allows for proper press-fitting without applying more pressure than necessary.

Preferably, the punch is capable of floating so that when the tip of the shaft-shaped part abuts against the mouth of the press-fit hole, the tip of the shaft-shaped part moves parallel to the press-fit hole. This allows the shaft-shaped part to follow the positional deviation of the press-fit hole caused by the floating of the receiving jig.

The press-fitting method of the present invention uses the press-fitting device to press a shaft-shaped part (90) into a press-fitting hole using the housing (80) as the workpiece. This press-fitting method includes a lowering step (S1), a receiving jig floating step (S2), and a press-fitting step (S4).

In the descending stage, the housing clamp and punch descend toward the housing. In the receiving jig floating stage, when the housing clamp abuts the clamping end face of the housing, the receiving jig floats so that it tilts with the point directly below the press-fit hole as a fulcrum. In the press-fit stage, the punch descends further, and the shaft-shaped part is pressed into the press-fit hole. This achieves the same effect as the press-fit device described above.

1A is a plan view, FIG. 1B is a front view, and FIG. 1C is a bottom view of a housing for a wastegate valve actuator, which is an example of a workpiece to be pressed in. FIG. 1 is a diagram showing a schematic image of a shaft (shaft-shaped part) press-fitting process. 1 is a flow chart of a press-in method using a press-in device according to one embodiment. FIG. 2 is a diagram of an upper mechanism of the press-fitting device according to one embodiment. 4A to 4C are diagrams showing the "setting stage" to the "lowering stage" of the press-fitting device according to one embodiment. FIG. 13 is a diagram of the receiving jig floating stage using the press-fitting device of one embodiment. FIG. 2 is a diagram of the punch floating stage using an embodiment of the pressing device. FIG. 2 is a diagram of the pressing stage using the pressing device of one embodiment. A diagram of the "press-in stage" when the press-in hole is not perpendicular to the clamping end face.

(One embodiment)
A press-fitting device according to an embodiment of the present invention and a press-fitting method using the press-fitting device will be described with reference to the drawings. The press-fitting device presses an axial part into a press-fit hole in a container-shaped housing as a workpiece to be pressed into the housing. First, referring to FIG. 1, the shape of a housing for a wastegate valve actuator used as a workpiece to be pressed into the housing in one embodiment will be described. FIG. 1(b) is a front view, and FIGS. 1(a) and 1(c) are a plan view seen from the direction Ia in FIG. 1(b) and a bottom view seen from the direction Ic, respectively.

The housing 80 is, for example, a casting made of an aluminum alloy, and has an opening 82 on the opposite side of the outer surface 81. The areas with dashed hatching in the plan view and bottom view indicate machined surfaces. The areas other than the machined surfaces are the cast surfaces. The machined surface 83 on the periphery of the opening 82 is used as the "holding end surface" in the press-fitting method.

The structure of a wastegate valve actuator is well known, as disclosed in, for example, JP 2019-78177 A. Inside the opening 82 of the housing 80, there are provided a motor insertion hole 86 in which the motor is housed, holes 87 and 88 in which an intermediate shaft for an intermediate gear that transmits motor rotation is press-fitted, and a hole 89 in which a bearing for a final gear is press-fitted. The intermediate shaft and bearing correspond to the "shaft-shaped parts" that are the objects to be press-fitted. In this embodiment, the press-fitting device and press-fitting method will be described using the press-fitting hole 88 in which the intermediate shaft for the second intermediate gear is press-fitted as an example.

In the press-fitting process, the housing 80 is supported horizontally from below by a receiving jig with the opening 82 facing upward, and the shaft-shaped part is pressed in from above. In the following explanation, the opening 82 side shown in FIG. 1(a) is referred to as "top", and the outer surface 81 side shown in FIG. 1(c) is referred to as "bottom". The flat surface shown in the bottom view is used as a load-bearing surface that abuts against the press-fit receiving jig. For example, the bottom surface 84 of the press-fit hole 88, the bottom surface 85 of another press-fit hole 89, and other casting surfaces are load-bearing surfaces.

Figure 2 shows a schematic image of the press-fitting process. Hereinafter, the intermediate shaft for the second intermediate gear will be simply referred to as "shaft 90". The shaft 90 is held by a punch 20 that can be raised and lowered. The specific configuration of the punch 20 will be described later with reference to Figure 4. The housing 80 is supported by a receiving jig 409 with the opening 82 facing upward. While holding the shaft 90, the punch 20 descends toward the press-fitting hole 88 and applies a press-fitting load, thereby pressing the shaft 90 into the press-fitting hole 88.

In the conventional press-fit process, the receiving surface is processed to stabilize the product's position, the perpendicularity of the press-fit hole relative to the receiving surface is ensured, and guide shapes are formed at the mouth of the press-fit hole and the tip of the pin, all of which are designed to make assembly easier. However, in recent years, there has been a trend to forcibly press the product in by applying a large press-fit load in order to reduce the number of processing steps.

Here, when the casting surface, not the machined surface, is supported by the support jig 40 and pressed in, the position of the support jig 40 is easily tilted. In particular, the press-in hole 88, which is located away from the center of gravity of the housing 80, is poorly balanced. Therefore, if the shaft 90 is pressed in by applying a press-in load that is greater than necessary to the tilted housing 80, there is a risk of insufficient press-in or cracking of the housing 80. There is also the problem that the press-in actuator requires more energy than necessary.

The purpose of the press-fitting device and press-fitting method of this embodiment is to reduce the average value of the press-fitting load by performing appropriate press-fitting without applying more than necessary press-fitting load, even if the housing 80 is tilted.

Next, the configuration of the press-fitting device 10 according to one embodiment and the method of press-fitting the shaft 90 using the press-fitting device 10 will be described with reference to Figures 3 to 9. In the flowchart in Figure 3, the symbol "S" denotes a step. After the setting step S0, the descending step S1, the receiving jig floating step S2, the punch floating step S3, the press-fitting step S4, and the ascent step S5 are carried out in that order.

The press-fitting device 10 is broadly divided into an upper mechanism that grasps the shaft 90 at the top of the housing 80 and raises and lowers it, and a lower mechanism that receives the housing 80. Figure 4 shows the upper mechanism. The punch 20 and housing presser 30 are attached so that they hang down from the lower end of the lifting rod 12 of the servo press, which serves as the driving device. Note that bolts and other members that fasten each member together are omitted from the illustration as appropriate.

The punch 20 includes a punch holder 21, an automatic misalignment correction device 22, a spacer 23, a bracket 24, a shaft holder 25, a load plate 28, etc. The punch holder 21 is attached to the lower end of the lifting rod 12 of the servo press, and raises and lowers each part of the punch 20 as a unit, and also raises and lowers the housing presser 30 in a height-displaceable state.

The automatic misalignment correction device 22 is a device that automatically corrects misalignment between the upper and lower shafts of the device, and may be, for example, a commercially available product. The spacer 23, bracket 24, and shaft holder 25 are coaxially connected to the lower part of the automatic misalignment correction device 22 by a spigot joint. This allows the axis Zw of the spacer 23, bracket 24, and shaft holder 25 to move horizontally parallel to the mechanical axis Zm of the servo press.

The shaft holder 25 has a set hole 26 formed with a diameter and length corresponding to the dimensions of the shaft-shaped part. A holding mechanism 27 is provided that opens into the inner wall of the set hole 26 and presses the outer circumferential surface of the shaft 90. The holding mechanism 27 is formed, for example, using a commercially available short plunger. The shaft 90 inserted from below the set hole 26 is held by the holding mechanism 27 with a force that does not cause it to fall under its own weight.

A high-hardness load plate 28 made of hardened steel or the like is provided between the bracket 24 and the shaft holder 25. The pressing load generated by the servo press is applied to the upper end of the shaft 90 via the load plate 28. The load plate 28 is used as a consumable part that is replaced when it deteriorates due to repeated pressing.

The housing retainer 30 is formed in a frame plate shape that can abut against the retaining end surface 83 of the housing 80. However, the housing retainer 30 does not need to have the exact shape of the retaining end surface 83, and may be formed in a simple ring disk shape as long as it can abut against the retaining end surface 83 in a balanced manner at multiple points.

The housing presser 30 has presser rods 31 connected to it at multiple circumferential locations (e.g., three locations spaced 120° apart). The presser rods 31 pass through guide holes 34 in guide bushes 33 provided on the periphery of the punch holder 21. Above and below the guide holes 34 in the punch holder 21, there are upper and lower covers 35 and 36 that prevent the guide bushes 33 from falling off.

Above the guide hole 34, a flange 32 that limits the downward limit of the pressing rod 31 is provided on the outer periphery of the pressing rod 31. Below the guide hole 34, a pressing spring 37 is provided as a "pressing biasing member" between the lower cover 36 and a spring seat 38 fixed to the housing presser 30.

As a result of being biased downward by the pressure spring 37, the housing pressure 30 comes into contact with the pressure end surface 83 of the housing 80, as shown in FIG. 6, and presses the housing 80 against the receiving jig 40. When the punch 20 further descends as shown in FIGS. 7 and 8, the housing pressure 30 and pressure rod 31 rise relative to the punch 20, as shown by the dashed lines.

Next, referring to Figures 5 to 8, the receiving jig 40 and the support post 50 as components of the lower mechanism of the press-fitting device 10 will be mainly described. The receiving jig 40 is generally block-shaped, and the upper surface 41 abuts against the receiving surfaces 84, 85 of the housing 80 from below to receive the housing 80. The portion of the receiving jig 40 opposite the housing 80, i.e., the lower surface 42 side, located directly below the press-fitting hole 88, is referred to as the portion directly below the press-fitting hole 45.

The support post 50 is substantially cylindrical and fixed on the base 16. The top 55 of the support post 50 is formed in a convex spherical shape. Here, the part 45 directly below the press-fit hole of the receiving jig 40 has a concave spherical shape with a radius slightly larger than the radius of the convex spherical surface of the top 55 of the support post 50. The top 55 of the support post 50 supports the part directly below the press-fit hole 45 by making point contact near the center of the part directly below the press-fit hole 45. Therefore, the receiving jig 40 is supported in a floating state so that it can tilt with the part directly below the press-fit hole 45 as a fulcrum.

A stripper bolt 61 serving as a "pull rod" is inserted through an insertion hole 56 formed along the axis of the support post 50. The stripper bolt 61 passes through the insertion hole 56 and is connected to a screw hole 44 formed in the portion immediately below the press-fit hole 45 of the receiving jig 40. A pull-down spring 63 serving as a "pull-down biasing member" is provided between the head 62 of the stripper bolt 61 and the spring seat portion 57 of the support post 50. The pull-down spring 63 biases the stripper bolt 61 downward, causing the portion immediately below the press-fit hole 45 of the receiving jig 40 to abut against the top 55 of the support post 50.

The auxiliary plate 13 is fixed to the base 16 via multiple supports 15 so as to face the underside 42 of the receiving jig 40 and surround the support post 50. As shown in FIG. 5, when the receiving jig 40 is in a horizontal position, a gap δ of about 0.5 mm is secured between the underside 42 of the receiving jig 40 and the auxiliary plate 13. When no press-fit load is applied, the receiving jig 40 is held horizontally by a holding mechanism 14 provided on the auxiliary plate 13. The holding mechanism 14 is configured using, for example, a commercially available short plunger.

Next, with reference to Figures 3 and 5 to 8, each stage of the press-fitting method using the press-fitting device 10 will be described. For convenience of explanation, the inclination of the housing 80 is exaggerated so that the pressing end surface 83 and the receiving surfaces 84 and 85 are not parallel to each other.

[S0 Set stage] to [S1 Fall stage]
5, in the setting step S0, the shaft 90 is set in the shaft holder 25 of the punch 20 at the original position where the servo press is raised. At this time, the length L1 from the lower end surface of the housing presser 30 to the tip of the shaft 90 is set shorter than the length L2 from the pressing end surface 83 of the housing 80 to the mouth of the press-fit hole 88. In the descending step S1, the housing presser 30 and the punch 20 descend from the original position toward the housing 80.

[S2 Receiving jig floating stage]
As shown in Fig. 6, in the receiving jig floating stage S2, the housing presser 30 abuts against the pressing end surface 83 of the housing 80. At this time, the receiving jig 40 floats so as to tilt with the portion directly below the press-fit hole 45 as a fulcrum (indicated by an arc-shaped double-headed arrow). Here, the load of the pressing spring 37 is set to be greater than the floating force. As a result, the posture of the housing 80 is corrected so that the pressing end surface 83 becomes horizontal following the housing presser 30. Accordingly, the center position Cw of the mouth of the press-fit hole 88 shifts with respect to the machine axis Zm.

[S3 Punch floating stage]
7, in the punch floating stage S3, the punch 20 further descends and the tip of the shaft 90 abuts against the mouth of the press-fit hole 88. At this time, the punch 20 floats such that the tip of the shaft 90 moves parallel to the press-fit hole 88 due to the action of the automatic core misalignment correcting device 22.

[S4 Press-in stage]
8, in the press-fitting step S4, the punch 20 is further lowered and the shaft 90 is press-fitted into the press-fitting hole 88. Here, it is assumed that the receiving jig 40 is in a floating state and the press-fitting hole 88 is perpendicular to the pressing end surface 83. After the press-fitting step S4, in the ascent step S5, the punch 20 and the housing presser 30 are raised and returned to their original positions. The housing 80 with the shaft 90 press-fitted is transported to the next process.

However, if the press-fit hole 88 is not perpendicular to the clamping end face 83, the press-fit hole 88 will be tilted relative to the shaft 90 when the receiving jig 40 is floating. In that case, as shown in FIG. 9, the receiving jig 40 will again float during the press-fitting process, and the clamping end face 83 will escape from the housing clamp 30, allowing the shaft 90 to be pressed straight into the press-fit hole 88.

(Effects of this embodiment)
(1) In the press-fitting device 10 of this embodiment, when the housing presser 30 comes into contact with the pressing end surface 83 of the housing 80, the receiving jig 40 can float so as to tilt with the portion directly below the press-fit hole 45 as a fulcrum. This allows the housing 80 to be corrected so that its posture is horizontal. Therefore, appropriate press-fitting can be achieved without applying a press-fitting load more than necessary.

We actually compared the press-fit load with and without the floating receiving jig. When the number of data points was about 30, the average press-fit load for the device of this embodiment was less than half that of the device without the floating receiving jig, and the standard deviation was also reduced to less than 30%.

(2) The press-fitting device 10 further includes a stripper bolt 61 that passes through an insertion hole 56 formed along the axis of the support post 50 and is connected to the part immediately below the press-fitting hole 45 of the receiving jig 40, and a pull-down spring 62 that urges the stripper bolt 61 downward so that the part immediately below the press-fitting hole 45 abuts against the top 55 of the support post 50. This determines the fulcrum during floating and prevents misalignment between the part immediately below the press-fitting hole 45 and the top 55 of the support post 50.

(3) By providing the punch 20 with an automatic core misalignment correction device 22, the punch 20 can float so that when the tip of the shaft 90 abuts against the mouth of the press-fit hole 88, the tip of the shaft 90 moves parallel to the press-fit hole 88. This allows the shaft 90 to follow the positional misalignment of the press-fit hole 88 caused by the floating of the receiving jig 40.

Other Embodiments
(a) In the floating mechanism of the receiving jig relative to the support post, a convex spherical portion may be formed on the receiving jig and a concave spherical portion may be formed on the support post, contrary to the above embodiment.

(b) The press-fitting device of this embodiment is not limited to the case where a shaft of a single diameter is pressed into a hole of a single diameter as an axial part, but may also be applied to the case where a shaft of multiple diameters is simultaneously pressed into multiple holes. In addition, the press-fitting workpiece can be applied to a container-like housing for any purpose that has a pressing end face on the periphery of an opening and a press-fitting hole formed inside the opening.

The present invention is not limited to the above-mentioned embodiment, and can be implemented in various forms without departing from the spirit of the invention.

10... Press-fitting device,
20...Punch,
30: Housing presser; 37: Presser spring (presser biasing member);
40: receiving jig; 45: directly below the press-fit hole;
80...Housing (press-fit workpiece),
82: opening; 83: pressing end surface;
84, 85: receiving surface; 88: press-fit hole;
90...Shaft (shaft-shaped part).

Claims (3)

A press-fitting device for pressing a shaft-shaped part (90) into a press-fit hole (88) formed inside a container-shaped housing (80) that has a pressing end surface (83) on the periphery of an opening (82), the press-fitting workpiece being a press-fitted workpiece, the press-fitting device comprising:
a receiving jig (40) that receives the housing by contacting from below with a receiving surface (84, 85) provided on the opposite side of the housing from the opening;
a housing presser (30) that is biased downward by a pressing biasing member (37) and abuts against the pressing end surface of the housing to press the housing against the receiving jig;
a punch (20) that holds the shaft-shaped part while descending toward the press-fit hole and applies a press-fit load;
a support post (50) for supporting a portion of the receiving jig directly below the press-fit hole (45) located directly below the press-fit hole on the opposite side of the receiving jig from the housing;
A pull rod (61) that passes through an insertion hole (56) formed along the axis of the support post and is connected to a portion directly below the press-fit hole of the receiving jig;
a downward biasing member (62) that biases the pull rod downward so that the portion immediately below the press-fitting hole abuts against the top (55) of the support post;
Equipped with
When the housing presser abuts against the pressing end surface of the housing, the receiving jig is capable of floating so as to tilt with a point directly below the press-fit hole as a fulcrum. 2. The press-fitting device according to claim 1 , wherein the punch is capable of floating so that when the tip of the shaft-shaped part abuts against the mouth of the press-fitting hole, the tip of the shaft-shaped part moves parallel to the press-fitting hole. A press-fitting method for pressing a shaft-shaped part (90) into a press-fit hole (88) formed inside a container-shaped housing (80) that is a workpiece to be pressed into, the housing having a pressing end surface (83) on the periphery of an opening (82) and a press-fit hole (88) formed inside the opening, the method comprising the steps of:
a receiving jig (40) that receives the housing by contacting from below with a receiving surface (84, 85) provided on the opposite side of the housing from the opening;
a housing presser (30) that is biased downward by a pressing biasing member (37) and abuts against the pressing end surface of the housing to press the housing against the receiving jig;
a punch (20) that holds the shaft-shaped part while descending toward the press-fit hole and applies a press-fit load;
a support post (50) for supporting a portion of the receiving jig directly below the press-fit hole (45) located directly below the press-fit hole on the opposite side of the receiving jig from the housing;
A pull rod (61) that passes through an insertion hole (56) formed along the axis of the support post and is connected to a portion directly below the press-fit hole of the receiving jig;
a downward biasing member (62) that biases the pull rod downward so that the portion immediately below the press-fitting hole abuts against the top (55) of the support post;
Using a press-fitting device (10) equipped with
a descending step (S1) in which the housing presser and the punch descend toward the housing;
a receiving jig floating step (S2) in which the receiving jig is floated so as to tilt with a part directly below the press-fit hole as a fulcrum when the housing presser abuts against the pressing end surface of the housing;
a press-fitting step (S4) in which the punch is further lowered and the shaft-shaped part is press-fitted into the press-fitting hole;
The pressing method includes:

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