JP7496665B2 - Crimping device and crimping method - Google Patents

Description

The present invention relates to a crimping device and a crimping method.

For example, in the automobile manufacturing process, crimping is used as a means of joining dissimilar materials together, as it creates a mechanical bond by plastically deforming one or both of the materials. Here, the crimping strength depends on the crimping method, but is usually affected by the amount of plastic deformation, so in this type of crimping process, it is important to manage the amount of plastic deformation during crimping or a parameter equivalent to this amount of deformation.

For example, Patent Document 1 describes controlling the stroke amount of the pushing part in the pushing direction when the nut is pushed in the axial direction to plastically deform the nut radially inward to connect with the bolt. In detail, Patent Document 1 proposes a crimping method including a process of determining a crimping depth that satisfies a predetermined condition, a process of determining a stroke amount of the pushing part that is equal to or greater than the determined crimping depth based on a predetermined relationship, a process of determining a stroke amount of the drive part that is equal to or greater than the determined stroke amount of the pushing part based on a predetermined relationship, and a process of controlling the drive part with a target control stroke amount that is equal to or greater than the determined stroke amount of the drive part and less than the stroke amount of the drive part at which a preset crimping part (plastic deformation part) breaks.

JP 2016-198774 A

However, when the actual member to be crimped is made of a specific material other than iron, which is a common automotive material, such as aluminum, there may be a large variation in hardness. If the hardness of the member to be crimped varies greatly in this way, when crimping is performed using a conventional method (stroke control) such as that described in Patent Document 1, there may also be a large variation in the amount of crimping (the amount of plastic deformation required to achieve the crimped state). On the other hand, since the allowable range of the amount of crimping is often set strictly (narrowly), when this type of joining means is applied to members with large variations in hardness, there is a problem in that it is difficult to keep the amount of crimping within the allowable range for all workpieces.

In light of the above, the technical problem to be solved in this specification is to keep the amount of crimping within a stable allowable range, even when the component being crimped is one that is prone to hardness variation.

The above-mentioned problems are solved by the crimping device of the present invention. That is, this device is characterized in that it includes a punch for crushing the crimped member and a control unit for controlling the driving of the punch, and in the crimping device for forming a crimped portion in the crimped member by plastic flow that occurs when the crimped member is crushed by the punch, the punch has a crushing portion at its tip that can crush the crimped member, and has a restricting surface that is located closer to the base end of the punch than the crushing portion and restricts the crushing by abutting against an area of the crimped member that is not crushed by the crushing portion, and the control unit is configured to be controllable to stop driving the punch in the crushing direction when it detects that the crimped member has abutted against the restricting surface during crushing.

In this way, in the crimping device according to the present invention, the punch for crushing the crimped member is provided with a restricting surface that is located closer to the base end of the punch than the crushing portion provided at the tip of the punch and restricts the crushing by abutting against the area of the crimped member that is not crushed by the punch. Therefore, by performing crimping using a punch provided with this restricting surface, the restricting surface restricts the crimped member from being crushed by a certain amount. Furthermore, when crimping is performed using a punch having this restricting surface, the driving of the punch in the crushing direction can be stopped when it is detected that the crimped member has abutted against the restricting surface, so that the crushing operation of the punch can be reliably stopped when the crushing amount reaches a certain amount. Therefore, even when a crimped member with a large variation in hardness is to be crimped, it is possible to stably keep the crimping amount within an acceptable range.

Alternatively, the above problem can also be solved by the crimping method of the present invention. That is, this method is a method for forming a crimped portion in a crimped member by plastic flow that occurs in the crimped member when the member is crushed with a punch, and is characterized in that a crushing portion capable of crushing the crimped member is provided at the tip of the punch, and a restricting surface is provided closer to the base end of the punch than the crushing portion, which restricts the crushing by abutting against an area of the crimped member that is not crushed by the crushing portion, and when it is detected that the crimped member has abutted against the restricting surface during crushing by the punch, the driving of the punch in the crushing direction is stopped.

In this way, in the crimping method according to the present invention, the crimping is performed using a punch for crushing the crimped member, which is provided with a restricting surface that is located closer to the base end of the punch than the crushing portion provided at the tip of the punch and restricts crushing by abutting against an area of the crimped member that is not crushed by the punch. Therefore, as with the crimping device according to the present invention, crushing of the crimped member by more than a certain amount is restricted by the restricting surface. Furthermore, if it is detected that the crimped member abuts against the restricting surface during crimping using a punch having this restricting surface, the driving of the punch in the crushing direction can be stopped, so that the crushing operation of the punch can be reliably stopped when the crushing amount reaches a certain amount. Therefore, even when the crimped member has a large variation in hardness, a stable crimping amount can be obtained.

In addition, in the crimping method according to the present invention, when the hardness of the crimped member shows a predetermined variation, the load during crushing is set so that the amount of crushing of the crimped member showing the upper limit of the variation in hardness is equal to or greater than the lower limit of the allowable range of the amount of crushing, and the position of the regulating surface in the crushing direction may be set so that the amount of crushing of the crimped member showing the lower limit of the variation in hardness is equal to or less than the upper limit of the allowable range of the amount of crushing.

According to the crimping method of the present invention, even if the crimped member has a lower limit of hardness variation among the crimped members having hardness variation, the regulating surface prevents excessive crushing, making it possible to obtain a stable amount of crimping. In addition, as described above, the load during crushing is set so that the amount of crushing of the crimped member having the upper limit of hardness variation is equal to or greater than the lower limit of the allowable range of the amount of crushing, and the position of the regulating surface in the crushing direction is set so that the amount of crushing of the crimped member having the lower limit of hardness variation is equal to or less than the upper limit of the allowable range of the amount of crushing. This makes it possible to obtain the desired amount of crimping not only for the crimped member having the lower limit of hardness variation, but also for the crimped member having the upper limit of hardness variation. In other words, even if the crimped member has a large hardness variation, it is possible to stably keep the amount of crimping within the desired range, regardless of the hardness.

As described above, according to the present invention, even when the component to be tightened is one that is prone to hardness variation, it is possible to keep the amount of tightening within a stable allowable range.

1 is a front view showing an overall configuration of a crimping device according to an embodiment of the present invention; FIG. 2 is an enlarged view of a portion A of the crimping device shown in FIG. 1 . 13 is an example of a graph showing the relationship between the hardness of a crimped member and the amount of crushing. 10 is a flowchart showing a control flow during crimping. 1A is an enlarged view of a main part at the start of crimping, and FIG. 1B is an enlarged view of a main part at the completion of crimping. 6A and 6B are graphs showing the relationship between the amount of crushing and the load during crimping.

The following describes the details of a crimping device and crimping method according to one embodiment of the present invention with reference to the drawings.

Figure 1 shows the overall configuration of the crimping device 10 according to this embodiment. That is, the crimping device 10 according to this embodiment includes a punch 11, a drive unit 12 that drives the punch 11, and a control unit 13 that controls the drive unit 12. Each element will be described in detail below.

In this embodiment, the crimped member 2 is crimped by crushing the end 2b of the crimped member 2, whose fitting hole 2a is fitted into the outer circumferential surface 1a of the shaft portion 1 that is to be crimped.

The punch 11 is capable of crushing the end 2b of the member to be fastened 2, and is positioned facing the end 2b of the member to be fastened 2. The punch 11 also has a circular crushing portion 14 at its tip (see FIG. 2), and is configured to be able to crush the end 2b of the member to be fastened 2, which also has a circular shape, in the axial direction over the entire circumference.

The punch 11 also has a restricting surface 15 for restricting the crushing of the crimped member 2, located closer to the base end of the punch 11 than the crushing portion 14 (upper side in FIG. 1). In this embodiment, the restricting surface 15 has a flat shape and is located on the outer periphery of the crushing portion 14. The radial dimension of the restricting surface 15 is set so that the contact area with the crimped member 2 is larger than that of the end face 14a of the crushing portion 14. The position of the restricting surface 15 in the crushing direction (the retreat amount R of the restricting surface 15 from the end face 14a of the crushing portion 14 toward the base end of the punch 11 in this embodiment) will be described later.

The driving unit 12 is capable of driving the punch 11 along the crushing direction of the crimped member 2, and is configured to be capable of linear reciprocating motion, for example. The driving unit 12 is also configured to be capable of detecting the position of the punch 11 in the crushing direction, and the reaction force that the punch 11 receives from the crimped member 2. Any means can be used as the driving unit 12 as long as it can drive the punch 11 in the above-mentioned manner, and for example, a servo cylinder that enables highly accurate load control is preferable.

The control unit 13 is capable of controlling the drive unit 12, and for example, as described below, is capable of controlling the drive of the punch 11 based on the magnitude of the reaction force that the punch 11 receives from the crimped member 2. In other words, the control unit 13 is capable of load-controlling the drive of the punch 11.

Next, we will explain the set load during crimping (crushing load) and the position of the regulating surface 15 in the crushing direction.

3 shows the relationship between the hardness H of the crimped member 2 and the amount of crushing C when the crimped member 2 is crimped. That is, as shown by the thick line in FIG. 3, at least in the crimping mode according to this embodiment, there is a certain correlation between the hardness H and the amount of crushing C. That is, as the hardness H increases, the amount of crushing C tends to decrease, and as the hardness H decreases, the amount of crushing C tends to increase. In this case, the thick line showing the relationship between the two parameters H and C tends to shift (translate) overall depending on the load at the time of crimping (load at the time of crushing). That is, the thick line tends to shift upward as the load at the time of crushing increases, and the thick line tends to shift downward as the load at the time of crushing decreases. In consideration of the above, for example, when the hardness H of the crimped member 2 varies from a lower limit H1 to an upper limit H2 as shown in Fig. 3, the magnitude of the crushing load is set so that the crushing amount C of the crimped member 2 showing the upper limit H2 of the variation in hardness H falls within the allowable range of the crushing amount C. In other words, when the lower limit of the allowable range of the crushing amount C is C1 and the upper limit is C2, the magnitude of the crushing load applied to the crimped member 2 by the punch 11 is set so that the crushing amount C of the crimped member 2 showing the upper limit H2 of the hardness H is at least equal to or greater than the lower limit C1 of the allowable range of the crushing amount C. As an example, if the crush amount C of the crimped member 2, whose hardness H indicates an upper limit value H2, is set to a predetermined value C3 that is greater than the lower limit value C1 of the allowable range, the magnitude of the crush load is set so that a thick line (dotted dash line) showing the relationship between the hardness H and the crush amount C passes through the intersection of the crush amount C3 and the hardness H2.

The position of the restricting surface 15 relative to the end face 14a of the crushing portion 14 is set so that the amount of crushing C of the crimped member 2, which has a lower limit H1 of the variation in hardness H, falls within the allowable range of the amount of crushing C with respect to the position of the restricting surface 15 along the crushing direction. That is, the position of the restricting surface 15 relative to the end face 14a of the crushing portion 14 (i.e., the amount of retreat R of the restricting surface 15 from the end face 14a of the crushing portion 14) is set so that the amount of crushing C of the crimped member 2, which has a lower limit H1 of hardness H, is equal to or less than the upper limit C2 of the allowable range of the amount of crushing C. As an example, when the amount of crushing C of the crimped member 2, which has a lower limit H1 of hardness H, is set to a predetermined value C4 smaller than the upper limit C2 of the allowable range, the position of the restricting surface 15 relative to the end face 14a of the crushing portion 14 (the amount of retreat R) is set to be equal to the predetermined value C4.

Next, an example of a crimping method using the crimping device 10 configured as described above will be described with reference to the flowchart shown in FIG.

First, the control unit 13 sends a command to the drive unit 12 to drive the punch 11 in the crushing direction (downward in Figure 1). In this case, the movement speed of the punch 11 is set to a predetermined magnitude. After driving starts, the drive unit 12 detects the reaction force that the punch 11 receives from the crimped member 2 at regular intervals. In reality, the predetermined reaction force can be detected when the crushing portion 14 of the punch 11 abuts against the end portion 2b of the crimped member 2 (see Figure 5(a)), and the reaction force increases as the crushing progresses (the punch 11 descends) (see Figure 6(a)).

Each time the reaction force is detected as described above, the control unit 13 judges whether the detected reaction force is equal to or greater than the preset threshold value T. Here, if the crimped member 2 is, for example, one that exhibits a value on the upper limit value H2 side of the variation in hardness H, the threshold value T is set to a value equal to the crushing load at which the value of the crushing amount C becomes a value C3 that is greater than the lower limit value C1 of the allowable range. If the detected reaction force is judged to be less than the threshold value T, the driving of the punch 11 in the crushing direction continues (see FIG. 4). Alternatively, if the detected reaction force is judged to be equal to or greater than the threshold value T, it is assumed that the end 2b of the crimped member 2 is crushed in the axial direction by the dimension C3, and a crimping portion 3 of the required size is formed inside the crushed area (see FIG. 5(b)), and the driving of the punch 11 in the crushing direction is stopped.

On the other hand, when the crimped member 2 has a value on the lower limit value H1 side of the variation in hardness H, the crushing amount C increases with a smaller load (reaction force) compared to when the crimped member 2 has a value on the upper limit value H2 side of the variation in hardness H (see FIG. 6(b)). Then, when the crushing amount C4, which is equal to the retreat amount R of the regulating surface 15, is reached, the area of the crimped member 2 that is not crushed, that is, the area radially outside the end 2b, comes into contact with the regulating surface 15 (see FIG. 5(b)). Therefore, the contact area between the punch 11 and the crimped member 2 increases rapidly, and the reaction force that the punch 11 receives from the crimped member 2 also increases rapidly (see FIG. 6(b)). As a result, when it is determined that the detected reaction force is equal to or greater than the threshold value T, it is considered that the end 2b of the crimped member 2 is sufficiently crushed and the crimped member 2 comes into contact with the regulating surface 15 of the punch 11, and the driving of the punch 11 in the crushing direction is stopped. This prevents the crimped member 2 from being crushed beyond the upper limit C2 of the allowable range.

As described above, in the crimping device 10 and crimping method according to this embodiment, the crimping is performed using a punch 11 for crushing the crimped member 2, which is provided with a restricting surface 15 that is located closer to the base end of the punch 11 than the crushing portion 14 provided at the tip of the punch 11 and restricts crushing by abutting against an area of the crimped member 2 that is not crushed by the punch 11. Therefore, crushing of the crimped member 2 exceeding a certain amount is restricted by the restricting surface 15. In addition, when the crimped member 2 abuts against the restricting surface 15 during crimping using the punch 11 having this restricting surface 15, the driving of the punch 11 in the crushing direction is stopped, so that the crushing operation of the punch 11 can be reliably stopped at the point when the crushing amount C reaches a certain size. Therefore, even when the crimped member 2 has a large variation in hardness H as the crimping target, a stable crimping amount can be obtained.

In addition, in this embodiment, when the hardness H of the crimped member 2 shows a predetermined variation, the load at the time of crushing is set so that the crush amount C of the crimped member 2 showing the upper limit value H2 of the variation of hardness H (see FIG. 3) is equal to or greater than the lower limit value C1 of the allowable range of the crush amount C, and the position (position in the crushing direction) of the regulating surface 15 is set so that the crush amount C of the crimped member 2 showing the lower limit value H1 of the variation of hardness H is equal to or less than the upper limit value C2 of the allowable range of the crush amount C. By setting the load C at the time of crushing in this manner and setting the position of the regulating surface 15 in the crushing direction, it is possible to obtain the desired crimping amount not only for the crimped member 2 showing the lower limit value H1 of the variation of hardness H, but also for the crimped member 2 showing the upper limit value H2 of the variation of hardness H. In other words, even if the crimped member 2 has a large variation in hardness H (H2-H1 is large), it is possible to stably keep the crimping amount within the desired range regardless of the hardness H.

Although one embodiment of the present invention has been described above, the crimping device and crimping method according to the present invention may have configurations other than those described above without departing from the spirit of the invention.

For example, in the above embodiment, the restricting surface 15 is illustrated as being flat and disk-shaped, but the shape of the restricting surface 15 is not limited to this. As long as it is possible to restrict the crushing of the crimped member 2 by the punch 11, the shape, attitude, and size of the restricting surface 15 are arbitrary, and it is advisable to set them taking into consideration, for example, the shape of the area of the crimped member 2 other than the area to be crushed (here, the end 2b).

In addition, in the above embodiment, the regulating surface 15 is provided as part of the punch 11, but of course other configurations are also possible. For example, a member having the regulating surface 15 may be manufactured separately from the punch 11 and attached to the outer periphery of the punch 11, thereby making it possible to regulate the crushing of the crimped member 2. By making it a separate member, the position of the regulating surface 15 in the crushing direction can be easily changed regardless of the timing of replacing the punch 11 due to wear of the crushing portion 14, for example.

In addition, in the above embodiment, the position of the punch 11 in the crushing direction and the force that the punch 11 receives from the crimped member 2 as a reaction force to the load when the punch 11 crushes the crimped member 2 are detected by the drive unit 12, but of course other configurations are also possible. The position of the punch 11 in the crushing direction and the crushing load may be measured directly or indirectly by a position measuring device such as a laser displacement meter provided separately from the drive unit 12 or a load measuring device capable of measuring load.

In the above embodiment, the crimped member 2 is crimped by setting the crushing load so that the value C3 of the crush amount C is close to the lower limit C1 of the variation when the crimped member 2 is crimped, whose hardness H indicates the upper limit H2 of the variation (see FIG. 6(a)). However, crimping may be performed under other conditions. That is, although not shown, the crushing load may be set so that the non-crushed area of the crimped member 2 comes into contact with the regulating surface 15 when the crimped member 2 is crimped, whose hardness H indicates the upper limit H2 of the variation. By setting in this way, the driving and stopping of the punch 11 in the crushing direction can always be controlled with the same threshold value, making the control mode very simple.

Reference Signs List 1 Shaft portion 1a Outer peripheral surface 2 Crimped member 2a Fitting hole 2b End portion 3 Crimping portion 10 Crimping device 11 Punch 12 Driving portion 13 Control portion 14 Crushing portion 14a End surface 15 Regulating surface C1 Lower limit C2 of allowable range of crushing amount Upper limit H1 of allowable range of crushing amount Lower limit H2 of hardness variation Upper limit R of hardness variation Amount of recession T from end surface of crushing portion Threshold value

Claims (5)

A crimping device includes a punch for crushing a crimped member and a control unit for controlling the driving of the punch, and is configured to form a crimped portion in the crimped member by plastic flow that occurs when the crimped member is crushed by the punch,
a load measuring device capable of measuring a load when the punch crushes the crimped member,
the punch has a crushing portion at its tip that is capable of crushing the crimped member, and a restricting surface that is located closer to the base end of the punch than the crushing portion and abuts against a region of the crimped member that is not crushed by the crushing portion to restrict the crushing,
the control unit controls the driving of the punch in the crushing direction to stop when it detects that the crushing amount of the crimped member has reached a size sufficient to form the crimped portion based on the load during crushing measured by the load measuring device,
A crimping device characterized by being configured to be controllable to stop driving of the punch in the crushing direction when it detects that the crimped member has come into contact with the regulating surface during the crushing based on the load during the crushing measured by the load measuring device. 1. A method for forming a crimped portion in a crimped member by plastic flow that occurs in the crimped member when the crimped member is crushed with a punch, comprising:
a crushing portion capable of crushing the crimped member is provided at a tip end of the punch, and a restricting surface is provided on a base end side of the punch relative to the crushing portion, the restricting surface contacting a region of the crimped member that is not crushed by the crushing portion to restrict the crushing;
The load when the punch crushes the crimped member can be measured,
when it is detected that the amount of crushing of the crimped member has reached a size sufficient to form the crimped portion based on the measured load during crushing, driving of the punch in the crushing direction is stopped;
A crimping method characterized by stopping the drive of the punch in the crushing direction when it is detected that the crimped member abuts the regulating surface during the crushing by the punch based on the measured load during the crushing . the control unit sets a load during the crushing so that, when the hardness of the crimped member shows a predetermined variation, a crushing amount of the crimped member showing an upper limit value of the variation in hardness is equal to or greater than a lower limit value of an allowable range of the crushing amount, and
The crimping device according to claim 1 , wherein the position of the restricting surface in the crushing direction is set so that the crushing amount of the crimped member, which indicates a lower limit of the variation in hardness, is equal to or less than an upper limit of an allowable range of the crushing amount. When the hardness of the crimped member shows a predetermined variation, a crushing load is set so that a crushing amount of the crimped member showing an upper limit value of the hardness variation is equal to or greater than a lower limit value of an allowable range of the crushing amount,
The crimping method according to claim 2 , wherein the position of the regulating surface in the crushing direction is set so that the crushing amount of the crimped member, which indicates a lower limit of the hardness variation, is equal to or less than an upper limit of an allowable range of the crushing amount. 1. A method for forming a crimped portion in a crimped member by plastic flow that occurs in the crimped member when the crimped member is crushed with a punch, comprising:
a crushing portion capable of crushing the crimped member is provided at a tip end of the punch, and a restricting surface is provided on a base end side of the punch relative to the crushing portion, the restricting surface contacting a region of the crimped member that is not crushed by the crushing portion to restrict the crushing;
when it is detected that the crimped member comes into contact with the regulating surface during the crushing by the punch, driving of the punch in the crushing direction is stopped,
When the hardness of the crimped member shows a predetermined variation, a crushing load is set so that a crushing amount of the crimped member showing an upper limit value of the hardness variation is equal to or greater than a lower limit value of an allowable range of the crushing amount,
A crimping method characterized in that the position of the regulating surface in the crushing direction is set so that the crushing amount of the crimped member, which indicates the lower limit of the hardness variation, is below the upper limit of the allowable range of the crushing amount.

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