CN111941052A - Automatic screw assembling machine - Google Patents

Abstract

The invention discloses an automatic screw assembling machine, wherein a screw loading station is arranged on a workbench, and the automatic screw assembling machine is characterized in that: the upper portion of the screw loading station is provided with temporary storage holes for temporary storage and positioning of screws to be assembled, the temporary storage holes can be opened movably, one or more temporary storage holes are formed, a screwdriver clamping head capable of moving up and down relative to the temporary storage holes is correspondingly arranged right above each temporary storage hole, the screwdriver clamping head is connected to an output shaft of the torque sensor, an input shaft of the torque sensor is in transmission connection with the servo motor, and output torque signals of the torque sensor during working control the output torque of the servo motor through the PLC. The invention can realize automatic screw assembly of workpieces, improve the efficiency, ensure the accurate control of the screw tightening force and reliably ensure the assembly quality.

Description

Automatic screw assembly machine

technical field

The invention relates to an automatic screw assembly machine for automatic screw assembly of workpieces.

Background technique

Many workpieces (such as motor end cover components and sensor end cover components) need to be connected and assembled by multiple screws. At present, a single screw is generally tightened one by one. The connection method is low in work efficiency, and there is also an imbalance in the tightening force of different screws in different positions. In addition, in order to make each screw have sufficient tightening force, a fixed torque electric screwdriver is usually used to tighten the screw, but the motor output torque of the electric screwdriver is often interfered by too many factors, and the tightening force of different screws will still exist. Large difference, coupled with the unbalanced tightening force of different screws at different positions, so at present, there is a common problem of unreliable quality of workpiece assembly, which leads to various failures such as easy loosening and short service life when the product is used.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the purpose of the present invention is to provide an automatic screw assembly machine that can realize automatic screw assembly of workpieces, improve efficiency, ensure precise control of screw tightening force, and reliably ensure assembly quality.

The present invention adopts following technical scheme to complete:

The automatic screw assembly machine has a screw loading station on the worktable. It is characterized in that: a temporary storage hole for temporary storage and positioning of the screw to be assembled is arranged above the screw loading station. The temporary storage hole can be movably opened, and the temporary storage There are one or more holes, and a screwdriver clamping head that can move up and down relative to the temporary storage hole is correspondingly located directly above each temporary storage hole. The screwdriver clamping head is connected to the output shaft of the torque sensor and the input shaft of the torque sensor. It is connected with the servo motor drive, and the output torque signal of the torque sensor is used to control the output torque of the servo motor through PLC.

The temporary storage hole includes an upper section hole, a lower section hole and a tapered hole connecting the upper and lower section holes. The temporary storage hole is surrounded by left and right claw blocks. The left and right claw blocks can be horizontally flipped and set on the fixed support plate, and the rear ends of the left and right claw blocks are provided with springs. Close the left and right claw blocks.

A guide tube for introducing the screw into the temporary storage hole is provided at the oblique upper part of the temporary storage hole.

A screwdriver guide hole is fixed directly above the temporary storage hole, and a guide sleeve is arranged in the screwdriver guide hole.

The torque sensor includes a seat body, an input shaft, an output shaft, an elastic sheet, a strain gauge and a circuit board. The input shaft and the output shaft are rotated on the seat body, and the elastic sheet is arranged between the input shaft and the output shaft to connect the two shafts. A Wheatstone bridge strain gauge is set on the elastic sheet to sense the tiny deformation of the elastic sheet during operation, and a signal conditioning circuit is arranged on the circuit board to adjust the discrete output signal of the strain gauge to a unified output range.

The seat body is provided with an upper cover and a lower cover, the input shaft is rotatably arranged on the upper cover through the upper bearing, the output shaft is arranged on the lower cover through the rotation of the lower bearing, and the output shaft is connected with the conductive slip ring.

The automatic screw assembly machine of the above technical solution can automatically tighten and assemble multiple screws to the workpiece at the same time, which greatly improves the efficiency, and also makes the tightening force of different screws in different positions to be balanced; and the screws are screwed in during the assembly process. The fixed output torque drives the screwdriver through the torque sensor, the torque sensor feeds back the load condition of the screwdriver tightening the screw in time, responds quickly and outputs the torque signal to the PLC in real time, and then the PLC corrects the fixed output torque parameter of the servo motor, thereby ensuring the screw tightening force. Precise control to reliably ensure assembly quality.

Description of drawings

The present invention has the following accompanying drawings:

Fig. 1 is the structural representation of the present invention,

Fig. 2 is a partial enlarged view of Fig. 1,

Fig. 3 is the state diagram of the present invention when working,

Figure 4 is a split structure diagram of the torsion sensor,

Figure 5 is a diagram of the connection structure of the torque sensor without the middle of the base body,

FIG. 6 is a separate installation structure diagram of the temporary storage hole, the guide tube and the screwdriver guide hole in FIG. 1 ,

FIG. 7 is a split structure diagram of FIG. 6 .

Detailed ways

As shown in the figure, in the automatic screw assembly machine of the present invention, the worktable 2 is provided with a screw loading station 1, the workpiece positioning fixture 13 can freely enter and exit the screw loading station 1 along the guide rail groove 14, and the workpiece positioning fixture 13 is used for The positioning of workpiece B during screw assembly. The rear side of screw loading station 1 is provided with a clamping cylinder. When the clamping cylinder is working, the clamping block 12 is pushed to act to press and fix the workpiece B positioned in the workpiece positioning fixture 13. (See Figure 4), a temporary storage hole 17 for the temporary storage and positioning of the screw A to be assembled is provided above the screw loading station 1. The temporary storage hole 17 can be movably opened, and the temporary storage hole 17 includes an upper hole, a lower hole and a connection The tapered hole 171 of the upper and lower holes, the temporary storage hole 17 is jointly enclosed by the left claw block 19 and the right claw block 20. The left and right claw blocks can be horizontally flipped on the fixed support plate 18 through their respective turning shafts 21. There is a spring 22 at the end to close the left and right claw blocks; there are four temporary storage holes 17, which are respectively aligned with the four screw mounting holes of the workpiece B, and the upper part of each temporary storage hole 17 is provided with a screw A into the temporary storage hole The guide tube 16 is arranged obliquely, the inlet end of the guide tube 16 is connected to the screw automatic conveying tube, and a screwdriver clamping head 10 is correspondingly provided directly above each temporary storage hole 17, and the screwdriver clamps The head 10 is used for clamping and fixing the screwdriver 11, and a screwdriver guide hole 15 is also fixed directly above the temporary storage hole 17. The screwdriver guide hole 15 is provided with a guide sleeve 151 to guide the screwdriver 11; the screwdriver clamping head 10 is connected to the torque The shaft end of the output shaft 51 of the sensor 4, the shaft end of the input shaft 41 of the torque sensor 4 is connected to the motor shaft of the servo motor 8 through the steering knuckle 6, the servo motor 8 is fixedly installed on the top plate 7, and the servo motor 8 is provided with the same four One-to-one corresponding to four screwdriver clamping heads 10, the torque sensor 4 is installed on the movable plate 3, the movable plate 3 can be moved up and down and is pushed by the lifting cylinder 9, the movable plate 3 and the top plate 7 are fixedly connected through the column 5, and the torque sensor 4 The output torque signal during operation controls the output torque of the servo motor 8 through the PLC.

The torque sensor 4 includes a seat body 47 , an input shaft 41 , an output shaft 51 , an elastic sheet 44 , a strain gauge 45 and a circuit board 46 , the seat body 47 has an upper cover 43 and a lower cover 50 , and the input shaft 41 is rotated through the upper bearing 42 . On the upper cover 43, the output shaft 51 is rotatably arranged on the lower cover 50 through the lower bearing 52, the output shaft 51 is fixedly connected to the shaft rod 48, the shaft rod 48 is connected to the conductive slip ring 49, and the inner ring of the conductive slip ring 49 is fixed to the shaft rod 48 , the outer ring of the conductive slip ring 49 is fixed with the seat body 47, the elastic sheet 44 is a spring steel sheet, and the elastic sheet 44 is arranged between the input shaft 41 and the output shaft 51 to connect the two shafts. The input shaft 41 and the shaft rod 48 are set There are corresponding connection slots and connection holes. The elastic sheet 44 is provided with a Wheatstone bridge strain gauge 45 to sense the tiny deformation of the elastic sheet 44 during operation. The strain gauge 45 is pasted and fixed on the surface of the elastic sheet 44 with high-energy glue. The circuit board 46 is provided with a signal conditioning circuit to adjust the discrete output signal of the Wheatstone bridge circuit of the strain gauge to a unified output range. The circuit board 46 is connected to the elastic sheet 44 through the connecting hole, and the signal conditioning circuit on the circuit board 46 is connected to PLC electrical connection

The present invention works as follows: the workpiece positioning fixture loaded with the workpiece is sent to the screw loading station, the clamping block compresses and fixes the workpiece, and at the same time, the screw is transported through the automatic conveying pipe and dropped to the guide pipe through the guide pipe. In the temporary storage hole, next, the movable plate goes down, and the four rotating screwdrivers move down to their respective temporary storage holes at the same time, drive the screws in the temporary storage holes to rotate and press down the screws, and the heads of the screws push down the tapered holes. The temporary storage hole is opened, so the screw is released from the temporary storage hole and screwed into the screw mounting hole of the workpiece until the four screws are tightened in place at the same time, which greatly improves the efficiency, and also enables the tightening force of the four screws in four different positions to maintain balance; During the above screw-in process, the constant output torque of the servo motor drives the screwdriver through the torque sensor. If the load condition of the screwdriver to tighten the screw changes, the strain gauge will be slightly deformed, and the Wheatstone bridge circuit set on the strain gauge will This deformation will be instantly sensed and the corresponding electrical signal will be sent. Since the signal sent by the Wheatstone bridge circuit is too discrete, the discrete output signal of the Wheatstone bridge circuit can be adjusted to a unified output range through the signal conditioning circuit on the circuit board. , so that the undisturbed stable and reliable output torque signal is transmitted to the PLC in real time, and the load condition of the screwdriver tightening the screw is fed back in time, and then the PLC corrects the fixed output torque parameter of the servo motor, thereby ensuring the precise control of the screw tightening force. Guaranteed assembly quality.

Claims (6)

1. Automatic screw assembly machine is equipped with the screw station of packing into on the workstation, its characterized in that: the upper portion of the screw loading station is provided with temporary storage holes for temporary storage and positioning of screws to be assembled, the temporary storage holes can be opened movably, one or more temporary storage holes are formed, a screwdriver clamping head capable of moving up and down relative to the temporary storage holes is correspondingly arranged right above each temporary storage hole, the screwdriver clamping head is connected to an output shaft of the torque sensor, an input shaft of the torque sensor is in transmission connection with the servo motor, and output torque signals of the torque sensor during working control the output torque of the servo motor through the PLC.

2. The automated screw assembling machine according to claim 1, wherein: the temporary storage hole comprises an upper section hole, a lower section hole and a taper hole for connecting the upper section hole and the lower section hole, the temporary storage hole is enclosed by a left claw block and a right claw block, the left claw block and the right claw block can be horizontally arranged on the fixed support plate in a turnover mode, and springs are arranged at the rear ends of the left claw block and the right claw block to enable the left claw block and the right claw block to be folded.

3. The automatic screw assembling machine according to claim 1 or 2, wherein: a guide tube for guiding the screw into the temporary storage hole is arranged obliquely above the temporary storage hole.

4. The automated screw assembling machine according to claim 1, wherein: a screwdriver guide hole is fixedly arranged right above the temporary storage hole, and a guide sleeve is arranged in the screwdriver guide hole.

5. The automated screw assembling machine according to claim 1, wherein: the torsion sensor comprises a base body, an input shaft, an output shaft, an elastic sheet, a strain gauge and a circuit board, wherein the input shaft and the output shaft are rotatably arranged on the base body, the elastic sheet is arranged between the input shaft and the output shaft to connect the two shafts, the elastic sheet is provided with a Wheatstone bridge strain gauge to sense the tiny deformation of the elastic sheet during working, and the circuit board is provided with a signal conditioning circuit to regulate the discrete output signals of the strain gauge into a uniform output range.

6. The automated screw assembling machine according to claim 5, wherein: the base body is provided with an upper cover and a lower cover, the input shaft is rotatably arranged on the upper cover through an upper bearing, the output shaft is rotatably arranged on the lower cover through a lower bearing, and the output shaft is connected with the conductive slip ring.

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