JP2004306115A - Apparatus and method for fastening self-boring type rivet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for fastening which realize fastening of a self-boring type rivet with a prescribed head surface height with respect to the surface of a member to be fastened, even when an elastic deformation occurs apparently between a punch and a nose piece due to strong punching force to the punch in punching of a self-boring type rivet in the apparatus for fastening. <P>SOLUTION: The apparatus for fastening a self-dipping type rivet includes the punch 22 and a die 23 for punching the self-boring type rivet into plurality of members to be fastened and the nose piece 18 movably supporting the punch toward the die and causing the punch to abut on the surface of the member to be fastened. The apparatus for fastening a self-dipping type rivet is provided with: a position measuring instrument 39 for measuring relative position between the nose piece 18 and the punch 22; an instrument 41 for measuring the punching force to the punch 22; a unit (42) which prepares and reserves a table for relative positional changing amount to the pushing force with respect to the changing amount of the relative position between the punch and the nose piece changed to reaction of the die against the pushing force of the punch based on the data from the position measuring instrument and the pushing force measuring instrument; and the unit (42) for correcting the pushing force to the punch by referring to the table for the relative positional change amount to the pushing force. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for fastening a self-piercing rivet having a head and a small-diameter hollow leg hanging from the head to a plurality of members to be fastened. The present invention relates to an apparatus and a method suitable for fastening members to be fastened, which are three or more panels (or panels and parts), to each other using self-piercing rivets.
[0002]
[Prior art]
One example of a self-piercing rivet setting device is described in Japanese Utility Model Laid-Open Publication No. 6-00930 (Patent Document 1), and FIG. 16 shows one example of a self-piercing rivet. The punch and die portions of a typical self-piercing rivet and fastening device currently used will be described with reference to FIGS. In FIG. 1, a self-piercing rivet 1 has a head 2 and a small-diameter hollow leg 3 (typically a cylindrical shape) hanging down from the head 2. As shown in FIG. 2, a self-piercing rivet 1 is formed by a plurality of members 7 such as two panels by a punch 5 movably supported by a nosepiece 4 of a fastening device and an opposite die 6. , 9 The leg 3 is deformed so as to extend the tip of the leg while penetrating the members 7, 9, and the members 7, 9 are connected to each other by the deformed expanding leg 10 and the head 2. You. Aluminum bodies are being adopted for automobile bodies whose weight is being reduced, and self-piercing rivets are suitable for connecting aluminum body panels that are not suitable for welding, and the demand for self-piercing rivets is increasing. I have. In particular, the self-piercing rivet 1 is driven so as to penetrate the fastened member 7 on the side of the punch 5, but not to penetrate the fastened member 9 on the receiving side adjacent to the die 6, but to stay therein. As a result, no rivet penetration hole is formed on the surface of the receiving-side fastened member 9, and the appearance is not impaired. Further, since there is no hole in the receiving-side fastened member 9, the sealing performance is not impaired. There are benefits too.
[0003]
In order to stably secure the fastening strength of the member to be fastened when driving the self-piercing rivet 1, the height H of the rivet 1 driven into the members 7 and 9 shown in FIG. Is the height H of the surface with respect to the surface of the member 7 to be fastened, which is defined as "increase (decillo)" in the present application. It is necessary to always maintain a constant (for example, 0.3 mm). . When the protrusion H changes, the amount by which the expanded and deformed tip 10 of the rivet leg penetrates the member to be fastened on the die side changes, and the tensile shear strength (the horizontal connection strength) of the plurality of members after fastening is changed. ) And peel strength (connection strength in the vertical direction) change, and the strength of fastening is not stable. On the other hand, if the protrusion H is too large, the protrusion on the surface of the member to be fastened is not preferable, and if the protrusion H is a negative value, the surface of the member to be fastened is not preferable. Therefore, in order to keep the projection H constant, as shown in FIG. 2, the relative position between the tip of the punch 5 in contact with the rivet head and the tip of the nose piece 4 in contact with the upper surface of the member 7 during rivet driving. Is monitored by the measuring device 11, and when the relative position reaches a predetermined indicated value, the driving H is determined to have reached a predetermined value and the driving is terminated.
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 6-0093030
[Patent Document 2]
JP-A-2002-192293
[0005]
[Problems to be solved by the invention]
As shown in FIG. 2, it is easy to monitor the relative position between the tip of the punch 5 and the tip of the nosepiece 4 and terminate the driving when the relative position reaches a predetermined instruction value. However, since the pressing force exceeding 10 kN is required for driving the self-piercing rivet, the relative position with respect to the nose piece gradually changes as the pressing force applied to the punch at the time of driving increases. It becomes as if elastic deformation occurred between the pieces. Generally, a C-shaped frame having high rigidity is used for the self-piercing rivet setting device. A nosepiece is attached to one end of the C-shaped frame. A punch is movably supported by the nosepiece toward the other end of the C-shaped frame, and a die is attached to the other end of the C-shaped frame so as to face the punch. In the C-type frame, a strong pressing force of 10 kN, 20 kNk, 30 kN, or the like is applied to the die at the other end from the nose piece side at one end, so that the other end supporting the die is strongly pressed and slightly elastic. Deform. The rigid C-shaped frame does not plastically deform due to the strong pressing force on the punch, but elastically deforms so that one end of the nosepiece and the other end of the die are separated, and when the pressing force on the punch is lost. To return. Since the die is pressed by this elastic deformation and the nose piece relatively moves away from the die, the relative distance between the tip of the nose piece and the tip of the punch also increases. Therefore, even if the measuring device 11 indicating the relative position between the tip of the nosepiece and the tip of the punch reaches a predetermined instruction value, the actual stocking H has not reached the set value. Even if the driving is terminated when the indicated value is reached, the driving will not be performed at an appropriate extra allowance. The allowable range of the allowance H is usually set in the range of several μm to 100 μm, so that it is necessary to finely adjust the set value of the measuring device 11 several times so that the set value of the measuring device 11 falls within the range for proper driving. There was troublesome work. Such elastic deformation can occur not only in the C-shaped frame but also in other mechanical connection systems between the nosepiece and the punch. If the diameter of the punch 5 is changed in order to change the size of the self-piercing rivet, the amount of the above-mentioned elastic deformation is different. Therefore, the fine adjustment of the set value of the measuring device 11 must be performed again for each punch having a different diameter. And the task is cumbersome and time consuming.
[0006]
Patent Literature 1 (Japanese Utility Model Application Laid-Open No. 6-0093030) discloses that even when the hardness of a member to be fastened or the temperature of oil in a hydraulic cylinder of a fastening device changes, the legs of a self-piercing rivet are changed. A fastening device that attempts to maintain a constant driving depth is disclosed. However, according to Patent Literature 1, when a self-piercing rivet is driven, apparently elastic deformation occurs between the punch and the nosepiece due to a strong pressing force on the punch, and the allowance does not reach the set value. Nothing is shown about the problem that the fastening ends in the state, and no solution is shown. Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2002-192293) discloses a C-shaped frame for softening a die (receiving punch) against a member to be fastened when driving a self-piercing rivet into the member to be fastened. A fastening device in which a balancing cylinder is provided between the mounting cylinder and the mounting base is disclosed. Also in Patent Document 2, when a self-piercing type rivet is driven, apparently elastic deformation occurs between the punch and the nosepiece due to a strong pressing force on the punch, and fastening is performed in a state where the allowance has not reached the set value. No indication is given for the failure that terminates, and no solution is given.
[0007]
Accordingly, an object of the present invention is to provide a self-piercing type rivet setting device which can generate a predetermined elastic deformation between the punch and the nosepiece due to a strong pressing force applied to the punch when driving the self-piercing type rivet. It is an object of the present invention to provide a fastening device and a method capable of fastening a self-piercing rivet with an allowance.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the present invention provides a punch and a die for driving a self-piercing rivet comprising a head and a hollow leg having a smaller diameter than the head into a plurality of members to be fastened. And a nose piece having a tip that abuts against the surface of the member to be fastened movably toward the die, and a punch is pressed toward the die inside the nose piece to form a self-piercing rivet into the member to be fastened. The legs are deformed such that the legs extend radially outward while the legs penetrate the member to be fastened, and the legs do not penetrate the member to be fastened adjacent to the die and remain therein. The present invention provides a self-piercing rivet setting device which is driven in such a manner that a plurality of members to be connected are interconnected by a deformed expanding leg and a head. This self-piercing rivet setting device has a position measuring device for measuring the relative position between the nose piece and the punch, and a device for measuring the pressing force on the punch, and further includes a position measuring device and a pressing force measuring device. A device for forming and storing a pressing force versus relative position change amount table for the amount of change in the relative position of the punch and the nosepiece, which changes with respect to the reaction force of the die with respect to the punch pressing force, based on the data from And a device for correcting the pressing force applied to the punch by referring to the pressing force versus relative position change amount table when the rivet is fastened.
[0009]
Further, the present invention provides a punch and a die for driving a self-piercing rivet including a head and a hollow leg portion having a smaller diameter than the head into a plurality of members to be fastened, and a punch directed toward the die. A nosepiece having a tip that supports the movable member and abuts against the surface of the member to be fastened, wherein a punch is pressed toward the die inside the nosepiece and the self-piercing rivet is driven into the member to be fastened, The leg is deformed so that the leg tip extends radially outward while penetrating the member to be fastened, and the leg tip is driven into the member to be fastened without penetrating the member to be fastened adjacent to the die. The present invention provides a self-piercing rivet fastening device that interconnects a plurality of members to be fastened by a deformed expanding leg portion and a head, the nose piece having a tip abutting on a surface of the member to be fastened. And ahead of the rivet head A position measuring device capable of measuring the relative position with respect to the punch with which the abutment comes into contact and measuring the extra allowance (the height of the surface of the rivet head driven into the member to be fastened relative to the surface of the member to be fastened), and Pressure measuring device that measures the pressing force of the punch, connected to the output of the position measuring device and the pressing force measuring device, and the relative position between the tip of the punch and the tip of the nosepiece that changes with respect to the reaction force of the die against the pressing force of the punch. Device for creating a table of the pressing force versus the relative position change amount based on the change amount, the table making device has a maximum pressing force of the punch disposed between the punch and the die prior to the fastening of the self-piercing rivet. When the tip of the nose piece is in contact with the reference plate having rigidity to withstand the pressure and the punch is pressed against the reference plate by applying the pressing force at the start of fastening, the position measuring device and The fastening start reference position of the position measuring device is set based on the data from the pressing force measuring device, and the pressing force of the punch increases and the relative pressure between the punch that presses the reference plate and the nose piece that contacts the reference plate is increased. A configuration in which a pressing force versus relative position change amount table is created and stored from the amount of change in the relative position between the pressing force of the punch and the tip of the punch and the tip of the nose piece obtained by changing the position. When the rivet is fastened, there is provided a device that corrects the pressing force to the punch by referring to the pressing force versus relative position change amount table, so that the head allowance of the self-piercing rivet is maintained at a predetermined value. It is characterized by being performed.
[0010]
In the above self-piercing rivet setting device, the rivet setting device includes a C-shaped frame, and the nosepiece is attached to one end of the C-shaped frame and movably supports the punch toward the other end of the C-shaped frame. The die is mounted on the other end of the C-shaped frame so as to face the punch so as to receive the self-piercing rivet, and the C-shaped frame has the nose piece supported on one end when the pressing force on the punch is strong and the other end on the other end. Although the relative distance to the supported die slightly increases, the rigidity can be restored when the pressing force is removed.
[0011]
Further, the present invention provides a punch and a die for driving a self-piercing rivet comprising a head and a hollow leg portion having a smaller diameter than the head into a plurality of members to be fastened, and a punch directed toward the die. A nosepiece having a tip that supports the movable member and abuts against the surface of the member to be fastened, wherein a punch is pressed toward the die inside the nosepiece and the self-piercing rivet is driven into the member to be fastened, The leg is deformed so that the leg tip extends radially outward while penetrating the member to be fastened, and the leg tip is driven into the member to be fastened without penetrating the member to be fastened adjacent to the die. The plurality of members to be fastened are connected to each other by the deformed and expanded legs and the head, and the tips of the nose piece and the head of the rivet are abutted against the surface of the member to be fastened. The relative position of the punch A position measuring device that can measure the height (excess allowance) of the surface of the rivet head measured and driven into the member to be fastened with respect to the surface of the member to be fastened, and a pressing force measuring device that measures the pressing force to the punch The present invention provides a method for fastening a self-piercing rivet using a self-piercing rivet fastening device that includes a self-piercing rivet fastening device, the method comprising: A rigid reference plate that can withstand the pressing force is arranged, the tip of the nosepiece and the die are brought into contact with the reference plate, and the pressing force at the start of fastening is applied to the punch to bring the tip of the punch into contact with the reference plate. Set the fastening start reference position of the position measuring device based on the relative position data of the nose piece and the punch and the pressing force data on the punch from the pressing force measuring device, and increase the pressing force on the punch From the relative position data from the position measuring device and the pressing force data from the pressing force measuring device, data on the amount of change in the relative position between the tip of the punch and the tip of the nosepiece, which changes with an increase in the pressing force on the punch, is obtained. Then, a table of the pressing force versus the relative position change amount is created and stored, and when fastening the self-piercing rivet, the pressing force on the punch is corrected by referring to the pressing force versus the relative position change amount table. Thus, the margin of the head of the self-piercing rivet is maintained at a predetermined value.
[0012]
As described above, a table of the pressing force versus the relative position change amount is created based on the change amount data of the relative position between the punch tip and the nose piece tip which changes with the increase in the pressing force on the punch, and the self-piercing is performed. When the mold rivet is fastened, the pressing force against the punch is corrected with reference to the pressing force versus relative position change table, so that the head of the self-piercing rivet can be protruded (the rivet head driven into the member to be fastened). (The height of the surface relative to the surface of the member to be fastened) is maintained at a predetermined value. Therefore, even if the self-piercing type rivet setting device applies a strong pressing force to the punch in driving the self-piercing type rivet and apparently deforms elastically between the punch and the nosepiece, the self-piercing type rivet after the driving is completed. The rivet allowance can be maintained at a predetermined value, the members to be fastened can be connected with high fastening strength, and the allowance value can be maintained at a set value, so that high fastening quality can be maintained. In addition, fine adjustment and repetition of the extra time are not required, and the number of work steps is reduced. In the adjustment of the allowance, the operation performed by the operator is only to arrange the reference plate between the punch and the die, and is not only simple, but also, for example, a re-adjustment (adjustment) operation after replacing parts of the fastening device. Similarly, it is only necessary to dispose the reference plate, which greatly reduces the trouble of the conventional adjustment work, and eliminates the need for dedicated parts used for the adjustment work.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 schematically shows the entirety of the self-piercing rivet setting device 13 according to one embodiment of the present invention. In FIG. 3, the self-piercing rivet setting device 13 has a rigid C-shaped frame 14, and a cylindrical housing 17 of a spindle unit 15 is fixed to one end (the upper end in FIG. 2) of the C-shaped frame 14. I have. The spindle portion 15 holds an elongated cylindrical nosepiece 18 slidably in the axial direction on the inner side on the distal end side thereof, and directs the distal end portion of the nosepiece 18 toward the other end (lower end) of the C-shaped frame 14. 14 is extended from one end (upper end). A receiver 21 for receiving the self-piercing rivet sent from the feeding tube 19 in a fixed posture is fixed to the tip of the nosepiece 18. Sent to the tip of 18. The nosepiece 18 is formed in a hollow shape, and a rod-shaped punch (indicated by reference numeral 22 in FIG. 4) is accommodated inside the nosepiece 18 so as to be slidable in the axial direction. The punch 22 acts to press the self-piercing rivet accommodated at the tip of the nosepiece 18 toward the other end (lower end) of the C-shaped frame 14. A die 23 is fixed at a position facing the punch 22 at the other end (lower end) of the C-shaped frame 14. As shown in FIG. 1, the leg 3 of the self-piercing rivet 1 is penetrated and fastened to the workpieces 7 and 9 by the punch 22 and the die 23.
[0014]
It is the spindle 15 that applies a pressing force to the punch 22 and moves the nosepiece 18 and the punch 22 in the axial direction. The spindle unit 15 will be described with reference to FIGS. The spindle portion 15 has a cylindrical housing 17 that slidably supports the nosepiece 18 (and the punch 22 inside the nosepiece 18). It has a main shaft 25 that moves down in cooperation. In order to drive the main shaft 25, the spindle unit 15 includes a servomotor 26, an optical encoder (or a shaft encoder) 27 that outputs the rotation angle and the number of rotations of the servomotor 26, and a torque by decelerating the rotation of the servomotor 26. It includes a reduction gear mechanism 29 that increases and turns back so as to shorten the linear length of the spindle portion 15, and a conversion mechanism 30 that converts the rotational motion into a linear motion and moves the main shaft 25 in the axial direction. The rotational motion sent from the servo motor 26 to the conversion mechanism 30 via the reduction gear mechanism 29 is converted by the conversion mechanism 30 into a movement for lowering or raising the main shaft 25. The tip (lower end) of the main shaft 25 directly contacts the upper end of the punch 22, and when the main shaft 25 is lowered, the punch 22 is pressed and lowered. The main shaft 25 is connected to the nosepiece 18 via a first coil spring 31 surrounding the outer peripheral surface. When the main shaft 25 is lowered, the nosepiece 18 is elastically pressed and lowered. Further, a second coil spring 32 that is weaker than the first coil spring 31 is provided on the outer peripheral surface of the punch 22. When the main shaft 25 is lowered, the punch 22 and the nosepiece 18 are lowered together by the first coil spring 31. When the tip of the nosepiece 18 comes into contact with the member to be fastened, the lowering of the nosepiece 18 stops there (FIG. 4). Position of the one-dot chain line). However, since the punch 22 is in direct contact with the main shaft 25, the punch 22 further descends by lowering the main shaft 25, extends from the tip of the nosepiece 18, presses the self-piercing rivet against the member to be fastened, and presses the leg. The fastening operation is performed on the plurality of fastened members by penetrating the fastened members.
[0015]
When it is detected that the height of the head of the driven self-piercing rivet from the surface of the member to be fastened, that is, the protrusion has reached a certain value, the servo motor 26 is rotated in the reverse direction assuming that the fastening of the member to be fastened has been completed. As a result, the main shaft 25 is raised, and the punch 22 is raised in the nosepiece 18 by the spring force of the second coil spring 32. Further, when the main shaft 25 is raised, the nose piece 18 is also raised together with the punch 22 by the spring force of the first coil spring 31 so as to separate from the member to be fastened, and returns to the position shown by the solid line in FIG. The servo motor 26 is provided with a connector 33 for an articulated robot arm or the like. The connector 33 allows the self-piercing rivet setting device 13 including the spindle unit 15 and the C-shaped frame 14 to be attached to the robot arm or the like. It is mechanically and electrically connected.
[0016]
As described above, the main shaft 25 directly presses the punch 22, but the nosepiece 18 presses indirectly via the first coil spring 31 so that the punch 22 can move in the axial direction with respect to the nosepiece 18. Supported. Since the moving length of the punch 22 is equal to the moving length of the main shaft 25 which directly presses the punch, it can be obtained from the rotation speed and rotation angle data from the optical encoder 27 connected to the servomotor 26. The nose piece 18 has the same movement length as the punch 22 until the tip contacts the member to be fastened, but hardly moves after the contact, but moves by elastic deformation as described in paragraph 0005, It may move within a range of several mm. The length of this movement determines the length of the next generation. Therefore, in order to detect the moving length, the nosepiece 18 is fixed with a meter 34 made of a transparent film in which a large number of grids are formed at a constant fine interval (for example, an interval of several μm). Is fixed to an optical sensor 35 composed of a light emitting element and a light receiving element that optically detects the grating of the meter 34 and outputs a pulse. As shown by the solid line in FIG. 4, at the home position when the fastening operation is not performed, the meter 34 and the optical sensor 35 are located apart from each other. During the fastening operation, the nosepiece 18 moves together with the punch 22 until the tip of the nosepiece 18 contacts the member to be fastened, so that the meter 34 moves with the nosepiece 18 as indicated by an arrow 37, When the tip of the piece 18 approaches the member to be fastened and moves to the position shown by the dashed line in FIG. 4, the meter 34 is organically associated so that its grating can be detected by the optical sensor 35. As described above, the metering ruler 34 is separated from the optical sensor 35 at the home position and is associated with the optical sensor only at the time of work, so that the metering ruler 34 can be shortened as shown in FIG. The length measurement range and measurement time can also be reduced.
[0017]
The pressing force of the punch 22 against the self-piercing rivet is measured by the spindle unit 15. For the measurement, in the illustrated embodiment, an annular load cell 38 is provided between the reduction gear mechanism 29 of the spindle unit 15 and the rotary motion-linear motion conversion mechanism 30. The load cell 38 outputs a measurement value signal obtained by the pressing force of the self-piercing rivet of the punch 22. More specifically, when the punch 22 is pressed by the main shaft 25, the tip of the punch presses the self-piercing rivet at the tip of the nosepiece 18. This pressing force is applied to the punch 22 as a reaction force when the self-piercing rivet penetrates the member to be fastened, and further serves as a force for pressing the load cell 38 via the main shaft 25 and the conversion mechanism 30. From the load cell 38 pressed by the reaction force to the punch 22, a measured value signal corresponding to the pressing force of the punch 22 is output.
[0018]
As described in the paragraph number 0005, even if the rigid C-shaped frame 14 is elastic between the nose piece 18 and the punch 22 due to the high pressing force applied to the punch when the self-piercing rivet is driven. Causes deformation. The C-shaped frame 14 is deformed so that the relative distance between the nose piece 18 supported at one end and the die 23 supported at the other end slightly increases when the pressing force on the punch 22 is strong. This deformation is not a plastic deformation but an elastic deformation that returns to the original state when the pressing force on the punch 22 is removed. This elastic deformation can occur not only in the C-shaped frame 14, but also in other mechanical connection systems between the nosepiece and the punch. In particular, when a punch having a different diameter is replaced to change the size of the self-piercing rivet, the amount of elastic deformation increases. Since the amount of this elastic deformation is different for each punch having a different diameter, it is necessary to redo the fine adjustment of the set value of the margin for each punch, and the operation is troublesome and time-consuming.
[0019]
According to the present invention, even if the self-piercing type rivet setting device apparently causes elastic deformation between the punch and the nosepiece due to a strong pressing force applied to the punch in driving the self-piercing type rivet, the self-piercing type rivet has a predetermined margin. Provided are a fastening device and a method capable of fastening a piercing rivet. Note that the allowance is a height at which the head surface of the rivet driven into the member to be fastened projects to the surface of the member to be fastened, and indicates H in FIG. This allowance is, for example, about 0.3 mm, and the allowable range is usually set in the range of several μm to 100 μm. In addition, when the allowance is a negative value, the surface of the member to be fastened is depressed, which is not preferable for a body panel surface of an automobile. In the driving of the self-piercing rivet, when it is detected that the height of the head of the driven self-piercing rivet from the surface of the member to be fastened reaches the set margin value, the fastening of the member to be fastened is completed. Is determined, the driving operation is completed, and the driving operation at the next position is started.
[0020]
Generally, in a self-piercing type rivet setting device, when a component such as a punch is replaced, a reference point (0 point) adjustment operation (representatively, a reference point (0 point) of the measuring device is reset). Adjustment work). In a conventional adjusting operation, when a punch is replaced, a pressing force of 15 kN or less is applied to the punch to reset a reference point. However, since the above-mentioned elastic deformation is not taken into consideration, the reference point is shifted as the pressing force is increased. If the user noticed a shift in the reference point, the resetting was repeated many times, and a delicate adjustment was made over a long period of time.
[0021]
As shown in FIG. 5, in the present invention, a setting and measurement system 40 for automatically setting a reference point and automatically measuring a change in time in a short time is introduced. In FIG. 5, the setting and measuring system 40 measures the relative position between the nose piece 18 having the tip abutting on the surface of the member to be fastened and the tip of the punch 22 having the tip abutting on the head of the self-piercing rivet. A position measuring device 39 for measuring the height (excess allowance) of the surface of the rivet head driven into the member to be fastened with respect to the surface of the member to be fastened, and a pressing force measuring device 41 for measuring the pressing force to the punch 22. Is further connected to the outputs of the position measuring device 39 and the pressing force measuring device 41, and is based on the amount of change in the relative position between the tip of the punch and the tip of the nosepiece that changes with respect to the reaction force of the die with respect to the pressing force of the punch. A processing device 42 including a device for creating a table of the pressing force versus the relative position change amount is provided. The position measuring device 39 receives the output from the optical encoder 27 connected to the servomotor 26 and the output from the optical sensor 35 that detects the grid position of the meter 34. In the position measurement device 39, the movement length of the punch is measured by the output from the optical encoder 27, and the distance between the nose piece 18 and the punch 22 relative to the optical sensor 35 that detects the grid position of the meter 34 is precisely determined. It is measured. The measurement data of the position measurement device 39 is input to a processing device 42 including a table creation device. The pressing force measuring device 41 receives a measurement value signal corresponding to the pressing force of the punch 22 from the load cell 38, outputs the signal as pressing force data, and inputs the data to a processing device 42 including a table creation device.
[0022]
The processing device 42 is configured by a computer system including a processor CPU, a read only memory ROM, a random access memory RAM, a hard disk drive HDD, an input / output device I / O, and the like. The processing device 42 receives the measurement data from the position measuring device 39 and the pressing force data from the pressing force measuring device 41 that measures the pressing force on the punch 22, and responds to the die reaction force against the punch pressing force. It functions as a device that creates a table of the pressing force versus the relative position change amount based on the changing amount of the relative position change between the punch tip and the nosepiece tip. The processing device 42 also functions as a device that corrects the pressing force applied to the punch 22 by referring to the pressing force versus relative position change table when the self-piercing rivet is fastened, and sends a correction signal to the servo motor 26. By sending 43, the pressing force to the punch is corrected. Further, the processing device 42 has another control function, for example, a normal control function of starting and stopping a servomotor in response to a command from a robot arm or the like. Further, the processing device 42 also performs automatic measurement and adjustment during the adjustment work. These operations are performed, for example, by the processor CPU performing an arithmetic processing operation according to a program stored in the read-only memory ROM and the random access memory RAM, a program stored in the hard disk of the hard disk drive HDD, and the like. An execution command is sent to the fastening device 13 through / O.
[0023]
Pressing force versus relative position change based on the amount of change in the relative position between the tip of the punch and the tip of the nosepiece that changes with the reaction force of the die against the pressing force of the punch created by the table forming device included in the processing device 42. The quantity table is a look-up table obtained by converting each graph shown in FIG. 6 into data. In FIG. 6, a first graph 45 shows a pressing force versus an elastic deformation amount, that is, a pressing force versus a relative position change amount in the case of a punch used for driving a self-piercing rivet having a diameter of 3 mm (φ3). The second graph 46 shows the pressing force versus the elastic deformation amount, that is, the pressing force versus the relative position change amount in the case of a punch used for driving a self-piercing rivet having a diameter of 5 mm (φ5). Actual data corresponding to these graphs is created as a look-up table by a table creation device included in the processing device 42.
[0024]
As shown in the first graph 45 and the second graph 46 of FIG. 6 described above, the pressing force is determined based on the amount of change in the relative position between the tip of the punch and the tip of the nosepiece, which changes with respect to the reaction force of the die with respect to the pressing force of the punch. A method of obtaining the relative position change amount table will be described with reference to the flowchart of FIG. First, prior to fastening of the self-piercing rivet, a rigid reference plate that can withstand the maximum pressing force of the punch 22 is disposed between the punch 22 and the die 23 at the tip of the nosepiece 18 (step 48). Next, the servomotor 26 is activated to bring the tip of the nosepiece 18 into contact with the reference plate (step 49). FIG. 5 shows a state in which the reference plate 47 is arranged on the die 23, the tip of the nosepiece 18 contacts the upper surface of the reference plate, and the tip of the punch 22 contacts. The reference plate has rigidity to withstand the maximum pressing force of the punch 22 (for example, 30 kN). Therefore, the reference plate is formed of a steel panel of 3 mm or more, whereby the position of the tip of the punch 22 with respect to the tip of the nosepiece 18 is fixed, and the pressing force from the punch 22 acts on the die 23. As a result, the blanking of the die 23 can be prevented.
[0025]
As shown in FIG. 5, the tip of the punch is brought into contact with the reference plate while a predetermined pressing force is applied to the punch 22 at the start of fastening (step 50). In this state, data from the position measuring device 39 and the pressing force measuring device 41 are sent to the processing device 42, and a nosepiece / punch relative position based on a predetermined pressing force at the start of fastening is calculated, and based on the relative position data. Then, a fastening start reference position (so-called zero point) of the position measuring device 39 is set (step 51). In this way, by simply placing the reference plate 47 between the punch 22 and the die 23, the setting of the fastening start reference position, that is, the reference point can be performed accurately and automatically in a short time. The pressing force at the start of fastening is ideally 0 kN, but actually requires a pressing force to slightly push the punch 22 from the nosepiece 18.
[0026]
Next, the servomotor 26 is further rotated to gradually increase the pressing force on the punch 22 via the main shaft 25 (step 52). Since the relative position change data of the nose piece and the punch from the position measuring device 39 and the pressing force data from the pressing force measuring device 41 which change according to the increase of the pressing force on the punch 22 are input to the processing device 42, From the amount of change in the relative position of the tip of the punch and the tip of the nosepiece with respect to the pressing force of the punch, which is obtained by increasing the pressing force of the punch and changing the relative position of the punch and the nosepiece, the pressing force versus the relative position The processing unit 42 creates a change amount table. The pressing force versus relative position change amount table is stored in, for example, a random access memory RAM or a hard disk of a hard disk drive HDD. Further, the pressing force versus relative position change amount table is preferably obtained by gradually increasing the pressing force to preferably 20 kN or more, and more preferably 30 kN or more, as shown in the graph of FIG. Further, creation of the pressing force vs. relative position change amount table, that is, the pressing force (load) vs. strain (nosepiece and punch system deformation) amount table is performed, for example, in the adjustment work that is conventionally required such as punch replacement. And man-hours do not increase. Such a pressing force versus relative position change amount table is created and stored for each punch having a different diameter (step 54). To create and save these pressing force versus relative position change tables, the operator simply performs the work of arranging the reference plate between the die and the punch. Do with.
[0027]
FIG. 8 shows a flowchart of an operation of actually driving and fastening a self-piercing rivet into a plurality of members to be fastened. First, in step 56, the C-shaped frame 14 is positioned so that the plurality of members to be fastened are sandwiched between predetermined positions of the punch 22 and the die 23. Also, the allowance (the height at which the rivet head after driving out of the surface of the member to be fastened) is set to a predetermined value (for example, 0.3 mm). Further, the fastening start reference position (point 0) of the position measuring device 39 is already determined as described above. A self-piercing rivet is automatically fed from the receiver 21 to the tip of the nosepiece 18, and the self-piercing rivet is arranged at the tip of the punch 22 (step 57). The operation of the servomotor 26 is started, and the punch 22 is pressed to start driving the self-piercing rivet into the member to be fastened (step 58). As shown in step 59, the pressing force on the punch 22 is increased to advance the driving of the self-piercing rivet, and during the driving, the correcting device included in the processing device 42 applies the pressing force to the punch 22. Is corrected by referring to the pressing force versus relative position change amount table corresponding to the diameter of the punch used. The corrected pressing force value is output as a correction signal 43 to the servomotor 26, and a signal for pressing to the punch movement length corresponding to the set margin is sent to the servomotor 26. As a result, the self-piercing rivet is driven into the member to be fastened so as to reach a proper margin. The punching amount of the punch 22 is pressed longer by the elastic deformation, and the pressing length is corrected by a pressing force versus relative position change amount table. When the processing device 42 determines that the relative position data from the position measuring device 39 has reached the predetermined margin value, the processing device 42 stops driving the servomotor 26 so as to remove the pressing force on the punch 22 and reverses the driving. And the fastening operation is terminated. The protrusion value of the self-piercing rivet after driving is the same as the set value, the members to be fastened are connected with high fastening strength, and the value of the protrusion can be maintained at the set value, so that high fastening quality can be maintained. Although the graphs 45 and 46 in FIG. 6 are shown in a straight line, actually, not only the elastic deformation of the C-shaped frame 14 but also the first coil spring 31 and the second coil spring 32 and other mechanical Due to the deformation in the dynamic connection system, it may not always be a straight line. However, since the table in which the pressing force versus relative position change amount table is created from the actually obtained data is referred to, it is possible to appropriately correct even if it changes linearly or non-linearly.
[0028]
【The invention's effect】
According to the present invention, a table of the pressing force versus the relative position change is created based on the change amount data of the relative position between the tip of the punch and the tip of the nosepiece which changes with the increase of the pressing force on the punch, and Since the pressing force against the punch is corrected with reference to the pressing force versus relative position change table when fastening the piercing type rivet, the margin of the head of the self-piercing type rivet is maintained at a predetermined value. Therefore, even if the self-piercing type rivet setting device applies a strong pressing force to the punch in driving the self-piercing type rivet and apparently deforms elastically between the punch and the nosepiece, the self-piercing type rivet after the driving is completed. The rivet allowance can be maintained at a predetermined value, the members to be fastened can be connected with high fastening strength, and the allowance value can be maintained at a set value, so that high fastening quality can be maintained. In addition, fine adjustment and repetition of the extra time are not required, and the number of work steps is reduced. In the adjustment of the allowance, the operation performed by the operator is only to arrange the reference plate between the punch and the die, and is not only simple, but also, for example, a re-adjustment (adjustment) operation after replacing parts of the fastening device. Similarly, only the arrangement of the reference plate is required, so that the trouble of the conventional adjustment work is greatly reduced, and the dedicated parts used for the adjustment work are not required.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a self-piercing rivet fastened to a member to be fastened, showing a height (an allowance) at which a rivet head comes out of the surface of the member to be fastened.
FIG. 2 is a cross-sectional view showing a conventional nosepiece, a punch, a member to be fastened, and a die, and is an explanatory view for measuring a relative position between the punch and the nosepiece.
FIG. 3 is a perspective view of a self-piercing rivet setting device according to an embodiment of the present invention.
FIG. 4 is a partial sectional view of a spindle unit of the self-piercing rivet setting device of FIG. 3;
FIG. 5 is a block diagram of a measurement and processing portion of the self-piercing rivet setting device according to one embodiment of the present invention.
FIG. 6 is a graph showing a relative position change amount between a nosepiece and a punch with respect to a pressing force applied to the punch.
FIG. 7 is a flowchart for obtaining a pressing force versus relative position change amount table according to the present invention.
FIG. 8 is a flowchart of driving a self-piercing rivet into a member to be fastened according to the present invention.
[Explanation of symbols]
1 Self-piercing rivets
2 Rivets head
3 legs
4 Nosepiece
5 Punch
6 dies
7, 9 member to be fastened
10 Deformation spread leg part
11 Measuring device
13 Self-piercing rivet setting device
14 C type frame
15 Spindle section
17 Housing
18 Nosepiece
19 Feeding tube
21 Receiver
22 Punch
23 die
25 spindle
26 Servo motor
27 Optical encoder
29 Reduction gear mechanism
30 Rotation-linear motion conversion mechanism
31 1st coil spring
32 2nd coil spring
34 meter
35 Optical Sensor
38 Load cell
39 Position measuring device
41 Pressing force measuring device
42 Processing device including table creation device and correction device
47 Reference plate

Claims (4)

A punch and a die for driving a self-piercing rivet comprising a head and a hollow leg having a diameter smaller than that of the head into a plurality of members to be fastened, and the punch being movable toward the die. A nosepiece having a tip that supports and abuts the surface of the member to be fastened, wherein the punch is pressed toward the die inside the nosepiece to strike the self-piercing rivet against the member to be fastened. When inserted, the leg is deformed so that the tip of the leg expands radially outward while penetrating the member to be fastened, and the tip of the leg is inserted into the member to be fastened without penetrating the member adjacent to the die. A self-piercing rivet fastening device, which is driven to stay and interconnects the plurality of members to be fastened by the deformed expanding leg portion and the head.
A position measuring device for measuring a relative position between the nosepiece and the punch, and a device for measuring a pressing force on the punch, further, data from the position measuring device and the pressing force measuring device A device for forming and storing a pressing force versus relative position change amount table for a change amount of a relative position of a punch and a nosepiece that changes with respect to a reaction force of a die with respect to a punch pressing force, and fastening of the self-piercing rivet A self-piercing type rivet setting device, comprising: a device for correcting the pressing force to the punch by referring to the pressing force versus relative position change amount table. A punch and a die for driving a self-piercing rivet comprising a head and a hollow leg having a diameter smaller than that of the head into a plurality of members to be fastened, and the punch being movable toward the die. A nosepiece having a tip that supports and abuts the surface of the member to be fastened, wherein the punch is pressed toward the die inside the nosepiece to strike the self-piercing rivet against the member to be fastened. When inserted, the leg is deformed so that the tip of the leg expands radially outward while penetrating the member to be fastened, and the tip of the leg is inserted into the member to be fastened without penetrating the member adjacent to the die. A self-piercing rivet fastening device, which is driven to stay and interconnects the plurality of members to be fastened by the deformed expanding leg portion and the head.
The relative position between the nose piece, the tip of which is in contact with the surface of the member to be fastened, and the punch, the tip of which is in contact with the head of the rivet, is measured on the surface of the rivet head that is driven into the member to be fastened. A position measuring device capable of measuring a height (excess allowance) with respect to the surface of the member to be fastened, a pressing force measuring device for measuring a pressing force applied to the punch, and outputs of the position measuring device and the pressing force measuring device A device that creates a table of the pressing force versus the relative position change based on the amount of change in the relative position between the tip of the punch and the tip of the nosepiece that changes with respect to the reaction force of the die with respect to the punch pressing force, The table making device includes a rigid reference plate that withstands the maximum pressing force of the punch disposed between the punch and the die before the self-piercing rivet is fastened, and the nose piece tip. When the punch is pressed against the reference plate by applying a pressing force at the start of fastening to the punch and applying the pressing force to the punch, the position is determined based on data from the position measuring device and the pressing force measuring device. By setting the fastening start reference position of the measuring device, and by increasing the pressing force of the punch, the relative position between the punch pressing the reference plate and the nose piece contacting the reference plate changes. The obtained pressing force versus relative position change amount table is created and stored from the obtained punch pressing force versus the relative position change between the punch tip and the nosepiece tip, and further, when fastening a self-piercing rivet. A device for correcting the pressing force on the punch by referring to the pressing force versus relative position change amount table, whereby the head of the self-piercing rivet is Self-piercing rivet fastening device, characterized in that the serial output margin is maintained at a predetermined value. Apparatus according to claim 1 or 2, including a C-shaped frame, wherein the nosepiece is mounted on one side of the C-shaped frame and is capable of moving the punch towards the other end of the C-shaped frame. The die is attached to the other end of the C-type frame so as to receive a self-piercing rivet, and is opposed to the punch. A self-piercing rivet setting device, wherein the relative distance between the nose piece supported at one end and the die supported at the other end slightly increases, but returns when the pressing force is removed. A punch and a die for driving a self-piercing rivet comprising a head and a hollow leg having a diameter smaller than that of the head into a plurality of members to be fastened, and the punch being movable toward the die. A nosepiece having a tip that supports and abuts the surface of the member to be fastened, wherein the punch is pressed toward the die inside the nosepiece to strike the self-piercing rivet against the member to be fastened. When inserted, the leg is deformed so that the tip of the leg expands radially outward while penetrating the member to be fastened, and the tip of the leg is inserted into the member to be fastened without penetrating the member adjacent to the die. The plurality of members to be fastened are connected to each other by the deformed expanding leg portion and the head, and further, the tip of which abuts on the surface of the member to be fastened. Nosepiece and front Measuring the relative position of the rivet head and the punch whose tip abuts on the rivet head to measure the height (extra allowance) of the surface of the rivet head driven into the member to be fastened relative to the surface of the member to be fastened. In a method of fastening a self-piercing rivet, using a self-piercing rivet fastening device including a position measuring device capable of and a pressing force measuring device for measuring the pressing force on the punch,
Prior to fastening the self-piercing rivet, a rigid reference plate that withstands the maximum pressing force of the punch is arranged between the punch and the die,
Abutting the tip of the nosepiece and the die on the reference plate, and applying a pressing force at the start of fastening to the punch so that the tip of the punch abuts on the reference plate;
Setting the fastening start reference position of the position measuring device from the relative position data of the nose piece and the punch from the position measuring device and the pressing force data to the punch from the pressing force measuring device,
Increasing the pressing force on the punch,
From the relative position data from the position measuring device and the pressing force data from the pressing force measuring device, a change in the relative position between the tip of the punch and the tip of the nosepiece that changes with an increase in the pressing force on the punch. After obtaining the amount data, create and save a table of pressing force vs. relative position change amount,
When the self-piercing rivet is fastened, the pressing force to the punch is corrected with reference to the pressing force versus relative position change table, whereby the protrusion of the head of the self-piercing rivet is determined. The method of fastening a self-piercing rivet, characterized in that the rivet is maintained at a value of:

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