A workpiece position correction system for stamping parts automatic welding line

Abstract

The invention discloses a workpiece position correction system for an automatic welding line for stamping parts, comprising a pin shaft and a support platform; the pin shaft comprises a positioning section, an upper conical section, an assembly section, and a lower conical section from top to bottom, the upper conical section and the lower conical section are coaxial and the conical surfaces face opposite directions; the support platform is provided with a through hole for the pin shaft to pass through on its surface, and limit bodies are respectively provided on the upper and lower sides, the limit bodies are provided with conical holes that can be combined with the conical surfaces of the upper conical section and the lower conical section. The workpiece position correction system for the automatic welding line for stamping parts adopts a floating pin shaft. During the assembly process, the pin shaft floats. After the assembly is completed, the pin shaft can be returned to rigid fixation to ensure the positioning accuracy, and the position of the pin shaft can be fine-tuned according to the positioning feedback of the pin shaft to adapt to the size error of the positioning hole between different batches of white bodies, reduce the collision between the pin shaft and the positioning hole, and avoid deformation of the positioning hole.

Description

Technical Field

[0001] The invention relates to the technical field of assembly line positioning fixtures, in particular to a workpiece position correction system for a stamping part automatic welding line. Background Art

[0002] In the process of welding the automobile body in white, most of them adopt flexible assembly lines for welding. As the number of welded parts on the body in white increases, the positioning method or positioning point will change, so the tooling fixtures at different stations are not the same. Therefore, when designing the assembly line, most of them will arrange corresponding tooling fixtures at different stations, and the body in white moves with the assembly line. After arriving at the designated station, it falls and is assembled and clamped with the tooling fixture for welding. After welding is completed, it is separated from the fixture and moves to the next station with the assembly line. By replacing the fixtures at different stations and the welding robot program, the replacement of assembly line products can be realized, and flexible production can be realized;

[0003] The body-in-white moves with the assembly line. When it falls and is assembled with the fixture, a locating pin is needed to position the workpiece. Most of the locating pins in the existing tooling fixtures are rigid locating pins, that is, the pin and the fixture are rigidly connected, which has good positioning performance. However, in the actual production process of the body-in-white, affected by the consistency of the workpiece, there is a certain deviation between the locating holes of the actual workpiece and the designed locating holes, that is, there is a certain drift in the size of the locating holes of the body-in-white of different production batches; even for the same batch of products, due to the coating thickness of the welding seam glue in the previous process, the difference in welding pressure of the spot welding gun, and the position of the welding point, there are also differences in the locating holes of different body-in-white; and this part of the locating hole difference has no effect on the safety and performance of the vehicle itself as long as it is within the design allowable range; however, since the actual height of the body-in-white is higher than its height in the fixture when it is circulating on the assembly line, when it is assembled with the fixture, there are problems such as the locating pin being hit or the edge of the locating hole being deformed and warped, which affects the positioning of the next process and causes a loss of positioning accuracy. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the existing defects and provide a workpiece position correction system for an automatic welding line for stamping parts. The system adopts a floating pin shaft. During the assembly process, the pin shaft floats. After the assembly is completed, the pin shaft can be returned to a rigid fixed state to ensure the positioning accuracy. The pin shaft can also be fine-tuned according to the positioning feedback of the pin shaft to adapt to the dimensional error of the positioning hole between different batches of white bodies, reduce the collision between the pin shaft and the positioning hole, and avoid deformation of the positioning hole. The system can effectively solve the problems in the background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a workpiece position correction system for a stamping part automatic welding line, comprising a pin and a support table;

[0006] The pin shaft comprises, from top to bottom, a positioning section, an upper conical section, an assembly section, and a lower conical section, wherein the upper conical section and the lower conical section are coaxial and have conical surfaces facing opposite directions;

[0007] The support platform has a through hole on its surface for the pin to pass through, and a limiting body is provided on the upper and lower sides respectively, wherein the limiting body is provided with a conical hole capable of combining with the conical surface of the upper conical section and the lower conical section, and the support platform is also provided with a telescopic rod for pulling the limiting body to move along the axis direction of the pin;

[0008] A plurality of groups of elastic members are connected and arranged between the outer circumferential surface of the assembly section and the support platform in a ring array.

[0009] As a preferred technical solution of the present invention, an assembly ring is coaxially rotatably arranged outside the assembly section, and the assembly ring is provided with a plurality of groups of assembly grooves along its tangential direction, the elastic member is clamped in the assembly groove, and a torque sensor fixedly connected to the support platform is provided at the other end of the elastic member;

[0010] The middle section of the pin shaft is connected to the support platform through an elastic part to give it a certain floating ability. When the white body is clamped, the pin shaft is driven to tilt to one side, the elastic part on the corresponding side is compressed, and the other side is stretched. The compression torque is detected by the torque sensor to preliminarily estimate the inclination of the pin shaft, and then further calculate the difference between the actual positioning holes of this batch of white bodies and the designed dimensions.

[0011] As a preferred technical solution of the present invention, an encoder is provided between the assembly ring and the pin shaft, and a flexible shaft is provided at the bottom end of the pin shaft to limit its rotation;

[0012] The expansion and contraction direction of the elastic part is consistent with the tangent direction of the assembly ring. Therefore, when the elastic part is compressed or stretched, it will drive the assembly ring and the pin to rotate relative to each other. Different inclination amounts of the pin correspond to different relative rotation angles, so as to further accurately calculate the inclination amount of the pin, and combine the differences in the measurement values ​​of multiple groups of torque sensors to determine the inclination direction, and further accurately calculate the difference in size between the BIW positioning hole and the designed positioning hole.

[0013] As a preferred technical solution of the present invention, a slide table capable of sliding along a horizontal plane is relatively fixedly arranged outside the support table, and the slide table is slidably mounted on the mounting frame through a servo system;

[0014] Combining the measurement values ​​of the torque sensor and the encoder, the size deviation between the BIW locating hole and the designed locating hole is calculated. The servo system drives the slide and the support table to slide, reducing the gap between the BIW locating hole and the designed locating hole. In addition, dynamic adjustments can be made during the production process to gradually reduce the error between the actual size and the designed size, thereby avoiding the collision of locating holes and loss of positioning accuracy caused by poor workpiece consistency.

[0015] As a preferred technical solution of the present invention, a guide rail sliding relative to the slide is arranged in the mounting frame, and the servo system includes a lead screw and a lead screw nut meshing with each other, the lead screw is parallel to the guide rail, the lead screw nut is fixed relative to the slide, and a drive motor is arranged at the end of the lead screw.

[0016] As a preferred technical solution of the present invention, the minimum diameter of the tapered hole of the limiting body is greater than the minimum shaft diameter of the tapered section of the pin shaft.

[0017] As a preferred technical solution of the present invention, both ends of the assembly section of the pin shaft are connected to the large diameter end of the tapered section, and the axial diameter of the assembly section is smaller than the axial diameter of the large diameter end of the tapered section, and the assembly ring is a two-petal structure, which facilitates the mutual assembly of the assembly ring and the pin shaft assembly section.

[0018] As a preferred technical solution of the present invention, the limiting body and the supporting platform are slidably installed along the axis direction of the pin shaft in the form of a sliding key.

[0019] Compared with the prior art, the invention has the following beneficial effects: the workpiece position correction system for the automatic welding line of stamping parts adopts an elastic member to connect the pin shaft and the support platform. When the upper end of the pin shaft contacts the workpiece, the top end of the pin shaft adopts a conical guiding structure. After being inserted into the positioning hole, when there is an error in the static position of the body-in-white on the assembly line, the axis of the positioning hole and the axis of the pin shaft do not overlap, and the guide pin shaft tilts. When the body-in-white drops to a specified height, the telescopic rod pulls the limit bodies on both sides to clamp the pin shaft. Through the interaction between the conical surface of the pin shaft and the conical hole of the limit body, the pin shaft is returned to the correct position, and the body-in-white is driven to move to the correct position, so that the rigid fixation of the pin shaft and the support platform is achieved, and the positioning accuracy is guaranteed.

[0020] At the same time, during the process of pin insertion and positioning, the torque sensor and encoder detect and calculate the inclination direction and inclination angle of the pin, and drive the slide and support table to move through the servo system to reduce the distance between the pin axis and the axis of the body-in-white positioning hole. By correcting multiple sets of body-in-white positioning data, the pin position is made consistent with the design position, thereby further improving the positioning accuracy and reducing the probability of collision between the pin and the positioning hole during the body-in-white clamping process, thereby ensuring the clamping accuracy and positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 A top view of the present invention;

[0023] Figure 3 It is a cross-sectional view taken along line AA of the present invention;

[0024] Figure 4 It is a cross-sectional view at BB of the present invention;

[0025] Figure 5 It is a cross-sectional view at CC of the present invention;

[0026] Figure 6 It is a schematic diagram of the assembly of the limiting body and the pin shaft of the present invention;

[0027] Figure 7 This is a schematic diagram of the assembly of the pin shaft and the support platform of the present invention;

[0028] Figure 8 It is a schematic diagram of the pin of the present invention;

[0029] Fig. 9 It is a schematic diagram of the assembly ring of the present invention.

[0030] In the figure: 1, pin; 2, support platform; 201, telescopic rod; 202, elastic member; 203, torque sensor; 3, upper limit body; 4, lower limit body; 5, assembly ring; 6, slide; 7, mounting frame; 701, guide rail; 8, servo system. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1-Figure 9 , the present invention provides a technical solution: a workpiece position correction system for a stamping part automatic welding line, comprising a pin 1 and a support table 2;

[0033] The pin 1 includes a positioning section, an upper conical section, an assembly section, and a lower conical section from top to bottom, wherein the upper conical section and the lower conical section are coaxial and the conical surfaces face opposite directions;

[0034] The support platform 2 is provided with a through hole for the pin shaft 1 to pass through on its surface, and a limiting body is provided on the upper and lower sides respectively, and a conical hole capable of combining with the conical surface of the upper conical section and the lower conical section is provided in the limiting body, and the support platform 2 is also provided with a telescopic rod 201 for pulling the limiting body to move along the axis direction of the pin shaft 1;

[0035] A plurality of groups of elastic members 202 are connected between the outer circumferential surface of the assembly section and the support platform 2 in a ring array.

[0036] See also Figure 5 , an assembly ring 5 is coaxially rotatably arranged outside the assembly section, and the assembly ring 5 is provided with a plurality of assembly grooves along its tangential direction, and the elastic member 202 is clamped in the assembly groove, and the other end of the elastic member 202 is provided with a torque sensor 203 fixedly connected to the support platform 2;

[0037] The middle section of the pin shaft 1 is connected to the support platform 2 through the elastic part 202, so that it has a certain floating ability. When the white body is clamped, the pin shaft 1 is driven to tilt to one side, and the elastic part 202 on the corresponding side is compressed, and the other side is stretched. The compression torque is detected by the torque sensor 203, and the inclination of the pin shaft 1 is preliminarily estimated, and then the difference between the actual positioning hole of this batch of white bodies and the designed size is further calculated.

[0038] See also Figure 3 and Figure 4 , an encoder is arranged between the assembly ring 5 and the pin 1, and a flexible shaft is arranged at the bottom end of the pin 1 to limit its rotation;

[0039] The expansion and contraction direction of the elastic member 202 is consistent with the tangent direction of the assembly ring 5, so that when the elastic member 202 is compressed or stretched, it will drive the assembly ring 5 and the pin shaft 1 to rotate relative to each other. Different inclination amounts of the pin shaft 1 correspond to different relative rotation angles, so as to further accurately calculate the inclination amount of the pin shaft 1, and combine the difference in the measurement values ​​of multiple groups of torque sensors 203 to determine the inclination direction, and further accurately calculate the difference value between the size of the white body positioning hole and the designed positioning hole.

[0040] See also Figure 1 A slide 6 capable of sliding along a horizontal plane is relatively fixedly arranged outside the support platform 2, and the slide 6 is slidably mounted on the mounting frame 7 through a servo system 8;

[0041] By combining the measurement values ​​of the torque sensor 203 and the encoder, the size deviation between the BIW positioning hole and the designed positioning hole is calculated, and the servo system 8 drives the slide 6 and the support table 2 to slide, thereby reducing the gap between the BIW positioning hole and the designed positioning hole. In addition, dynamic adjustments can be made during the production process to gradually reduce the error between the actual size and the designed size, thereby avoiding the problem of positioning hole collision and loss of positioning accuracy caused by poor workpiece consistency.

[0042] A guide rail 701 is provided in the mounting frame 7 and slides relative to the slide 6. The servo system 8 includes a lead screw and a lead screw nut meshing with each other. The lead screw is parallel to the guide rail 701, the lead screw nut is fixed relative to the slide 6, and a driving motor is provided at the end of the lead screw.

[0043] See also Figure 3 , the minimum diameter of the tapered hole of the limiting body is greater than the minimum shaft diameter of the tapered section of the pin shaft 1.

[0044] Both ends of the assembly section of the pin shaft 1 are connected to the large diameter end of the tapered section, and the shaft diameter of the assembly section is smaller than the shaft diameter of the large diameter end of the tapered section. The assembly ring 5 is a two-petal structure, which facilitates the mutual assembly of the assembly ring 5 and the assembly section of the pin shaft 1.

[0045] The limiting body and the supporting platform 2 are slidably installed along the axis direction of the pin shaft 1 in the form of a sliding key.

[0046] When in use: fix the mounting frame 7 and the fixture relatively, the direction of the guide rail 701 is consistent with the direction of the positioning hole with a larger error. For example, when welding the chassis, the direction of the larger deformation error is the length direction of the vehicle body, so the direction of the guide rail 701 is consistent with the length direction of the vehicle body;

[0047] Before use, the two petals of the assembly ring 5 are respectively installed into the assembly section 1a of the pin shaft 1 from both sides and fixed by the hexagon socket bolts, and a limiting protrusion is set in the assembly groove 5a of the assembly ring 5, and the elastic member 202 is inserted into the limiting protrusion 5b. The torque sensor 203 at the other end is fixed to the support platform 2, and the bottom of the pin shaft 1 is connected to the flexible shaft, and the other end of the flexible shaft is relatively fixed to the support platform 2 to ensure that the pin shaft 1 will not rotate around its own axis during operation;

[0048] The limiting body includes an upper limiting body 3 located above the support platform 2 and a lower limiting body 4 below the support platform 2. In the initial stage, the two are located away from the support platform 2. When the pin shaft 1 is fully inserted into the positioning hole, under the action of the telescopic rod 201, the upper limiting body 3 and the lower limiting body 4 are driven close to the support platform 2, and at the same time contact with the upper conical section 1b and the lower conical section 1c of the pin shaft 1 to ensure the coaxiality of the upper limiting body 3, the pin shaft 1 and the lower limiting body 4; at the same time, the top end of the pin shaft 1 adopts a conical guide section 1f, and a limiting shoulder 1d is set at the bottom of the positioning section; the telescopic rod 201 is preferably a cylinder, which has the advantage of fast response.

[0049] When the designed positioning hole is not coaxial with the BIW positioning hole, that is, the pin 1 is tilted toward the BIW positioning hole when inserted into the positioning hole. At this time, the measured values ​​of the torque sensor 203 at different positions in the support platform 2 are different, among which the measured value of the tilted compression side is the largest, and the assembly ring 5 is acted upon by the elastic member 202, which pushes it to rotate relative to the pin 1, and the relative rotation amount is proportional to the tilt angle, that is, the actual tilt amount of the pin 1 can be converted according to the relative rotation amount, and the spacing value between the designed positioning hole and the BIW positioning hole is calculated according to the tilt amount of the pin 1, the tilt direction of the pin 1, and the length of the pin 1 itself, so as to control the servo system 8 to adjust the position of the slide 6, reduce the spacing between the axis of the pin 1 and the axis of the BIW positioning hole, and avoid the pin 1 from hitting the edge of the positioning hole.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A workpiece position correction system for a stamping parts automatic welding line, comprising a pin (1) and a support table (2), characterized in that: The pin shaft (1) comprises, from top to bottom, a positioning section, an upper conical section, an assembly section, and a lower conical section, wherein the upper conical section and the lower conical section are coaxial and have conical surfaces facing opposite directions; a support platform (2) having a through hole provided on its surface for the pin shaft (1) to pass through, and a limiting body provided on the upper and lower sides, wherein the limiting body is provided with a conical hole capable of engaging with the conical surfaces of the upper conical section and the lower conical section, and the support platform (2) is further provided with a telescopic rod (201) for pulling the limiting body to move along the axis direction of the pin shaft (1); a plurality of groups of elastic members (202) are provided in a ring array between the outer circumferential surface of the assembly section and the support platform (2), an assembly ring (5) is provided on the outside of the assembly section for coaxial rotation, and the assembly ring (5) is provided with a plurality of groups of assembly grooves along its tangential direction, the elastic member (202) is clamped in the assembly groove, and a torque sensor (203) fixedly connected to the support platform (2) is provided at the other end of the elastic member (202).

2. The workpiece position correction system for stamping parts automatic welding line according to claim 1 is characterized in that: An encoder is provided between the assembly ring (5) and the pin shaft (1), and a flexible shaft is provided at the bottom end of the pin shaft (1) to limit its rotation.

3. The workpiece position correction system for stamping parts automatic welding line according to claim 1 or 2, characterized in that: A slide table (6) capable of sliding along a horizontal plane is relatively fixedly arranged outside the support table (2); the slide table (6) is slidably mounted on the mounting frame (7) via a servo system (8).

4. The workpiece position correction system for stamping parts automatic welding line according to claim 3 is characterized in that: A guide rail (701) is provided in the mounting frame (7) and slides relative to the slide table (6). The servo system (8) comprises a lead screw and a lead screw nut that mesh with each other. The lead screw is parallel to the guide rail (701), the lead screw nut is fixed relative to the slide table (6), and a drive motor is provided at the end of the lead screw.

5. The workpiece position correction system for stamping parts automatic welding line according to claim 1, characterized in that: The minimum diameter of the tapered hole of the limiting body is greater than the minimum shaft diameter of the tapered section of the pin shaft (1).

6. The workpiece position correction system for stamping parts automatic welding line according to claim 1, characterized in that: Both ends of the assembly section of the pin shaft (1) are connected to the large diameter end of the tapered section, and the shaft diameter of the assembly section is smaller than the shaft diameter of the large diameter end of the tapered section. The assembly ring (5) is a two-petal structure.

7. The workpiece position correction system for stamping parts automatic welding line according to claim 5, characterized in that: The limiting body and the support platform (2) are slidably mounted along the axis direction of the pin shaft (1) in the form of a sliding key.

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