Method of producing a riveted joint

Abstract

A joining method for setting a rivet in a workpiece comprises the steps of: providing a setting tool including a frame, a punch, a die, a clamping device, a drive unit, and a control device; providing a predetermined maximal rivet setting speed to the control device; providing the rivet and the workpiece; feeding the rivet into the setting tool; and setting the rivet in the workpiece, the setting step further comprising: moving the punch at a first punch speed; slowing the punch to a second punch speed before the rivet contacts the workpiece; and driving the rivet into the workpiece by moving the punch and monitoring the punch to ensure the punch does not exceed the predetermined maximal rivet setting speed.

What is claimed is: 
     
         1 . A joining method for setting a rivet in a workpiece comprising the steps of:
 providing a setting tool comprising a frame, a punch that is displaceable on the frame along a joining axis (X), a die that is mounted on the frame, a clamping device with which one or more components can be compressed in a joining direction, and the punch being guided in the clamping device by a drive unit and a control device;   providing a predetermined maximal rivet setting speed,   providing the rivet,   feeding the rivet into the setting tool, and   setting the rivet in the workpiece, the setting step further comprising:   in a first stage, moving the punch at a first punch speed (S 1 );   in a second stage, slowing the punch until the punch reaches a second punch speed (S 2 ), wherein the second punch speed is reached at the latest when the rivet first contacts the workpiece, the second punch speed is less than the first punch speed; and   in a third stage, moving the punch and monitoring the punch to ensure the punch does not exceed the predetermined maximal rivet setting speed.   
     
     
         2 . The joining method according to  claim 1 , further comprising a step of defining a predetermined maximal rivet length, and the rivet defines a length less than the predetermined maximal rivet length, and the second punch speed is reached when the punch arrives at a position equal to the predetermined maximal rivet length from the workpiece. 
     
     
         3 . The joining method according to  claim 1 , wherein the first punch speed (S 1 ) is within a range of 150-1000 mm/s. 
     
     
         4 . The joining method according to  claim 1 , wherein the second punch speed (S 2 ) and/or the maximal predetermined rivet setting speed is within a range of 10-300 mm/s. 
     
     
         5 . The joining method according to  claim 1 , wherein the predetermined maximal rivet setting speed is below 100 mm/s. 
     
     
         6 . The joining method according to  claim 1 , wherein the drive unit slows the punch such that the second rivet speed (S 2 ) is no more than the predetermined maximal rivet setting speed when the rivet first contacts the workpiece. 
     
     
         7 . The joining method according to  claim 2 , wherein the drive unit slows the punch such that the second rivet speed (S 2 ) is no more than the predetermined maximal rivet setting speed when the punch arrives at a position equal to the predetermined maximal rivet length from the workpiece. 
     
     
         8 . The joining method according to  claim 1 , wherein a deformation of the frame during the setting step is detected by a monitoring unit and a course of movement during the setting step is corrected as a function of the deformation. 
     
     
         9 . The joining method according to  claim 1 , wherein a first relative movement between the frame and the clamping device is measured by a first sensor and/or a second relative movement between the frame and the punch is measured by a second sensor. 
     
     
         10 . The joining method according to  claim 9 , wherein the first sensor and/or the second sensor is a linear path recorder. 
     
     
         11 . The joining method according to  claim 1 , wherein the workpiece includes a first workpiece and a second workpiece, and the first workpiece is a high strength steel workpiece. 
     
     
         12 . The joining method according to  claim 11 , wherein the workpiece further includes a third workpiece, and first workpiece and the second workpiece are two upper layers and are high strength steel workpieces. 
     
     
         13 . The joining method according to  claim 1 , wherein the predetermined maximal rivet setting speed is adjustable. 
     
     
         14 . A joining method for setting a rivet in a workpiece comprising the steps of:
 providing a setting tool comprising a frame, a punch that is displaceable on the frame along a joining axis (X), a die that is mounted on the frame, a clamping device with which the workpiece can be compressed in a joining direction, and the punch being guided in the clamping device by a drive unit and a control device;   providing a predetermined maximal rivet setting speed to the device;   providing the rivet and the workpiece;   feeding the rivet into the setting tool; and   setting the rivet in the workpiece, the setting step comprising:   moving the punch at a first punch speed (S 1 );   slowing the punch from the first punch speed until the punch is moving at a second punch speed (S 2 ) less than the first punch speed, and the second punch speed is reached no later than when the rivet first contacts the workpiece, and   while the rivet penetrates into the workpiece, moving the punch at a third punch speed, monitoring the third punch speed, and maintaining the third punch speed at no more than the predetermined maximal rivet setting speed.   
     
     
         15 . The joining method according to  claim 14 , further comprising a step of defining a predetermined maximal rivet length not less than a length of the rivet, and the second punch speed is reached when the punch arrives at a position equal to the predetermined maximal rivet length from the workpiece. 
     
     
         16 . The joining method according to  claim 14 , wherein the first punch speed (S 1 ) is within a range of 150-1000 mm/s. 
     
     
         17 . The joining method according to  claim 14 , wherein the second punch speed (S 2 ) and/or the maximal predetermined rivet setting speed is within a range of 10-300 mm/s. 
     
     
         18 . The joining method according to  claim 14 , wherein the predetermined maximal rivet setting speed is below 100 mm/s. 
     
     
         19 . The joining method according to  claim 14 , wherein the step of setting the rivet, the drive unit slows the punch such that the second rivet speed (S 2 ) is no more than the predetermined maximal rivet setting speed when the rivet first contacts the workpiece. 
     
     
         20 . The joining method according to  claim 15 , wherein the step of setting the rivet, the drive unit slows the punch such that the second punch speed (S 2 ) is no more than the predetermined maximal rivet setting speed when the punch arrives at a position equal to the predetermined maximal rivet length from the workpiece. 
     
     
         21 . The joining method according to  claim 14 , wherein the setting step further comprises: detecting a deformation of the frame by a monitoring unit and adjusting a course of movement as a function of the deformation detected. 
     
     
         22 . The joining method according to  claim 21 , wherein a first relative movement between the frame and the clamping device is measured by a first sensor and/or a second relative movement between the frame and the punch is measured by a second sensor. 
     
     
         23 . The joining method according to  claim 22 , wherein the first sensor and/or the second sensor is a linear path recorder. 
     
     
         24 . The joining method according to  claim 14 , wherein the workpiece includes a first workpiece and a second workpiece, and the first workpiece comprises a high strength steel. 
     
     
         25 . The joining method according to  claim 24 , wherein the workpiece further includes a third workpiece, and the second workpiece comprises a high strength steel. 
     
     
         26 . The joining method according to  claim 14 , wherein the predetermined maximal rivet setting speed is adjustable in the control device. 
     
     
         27 . The joining method according to  claim 21 , wherein the step of adjusting a course of movement further comprises:
 calculating a rectification tool force in the control device with the input of the monitoring unit; and/or   adjusting a position of the punch and/or the third punch speed to achieve a predetermined target position for the rivet in the workpiece.