Riveting Tool for High-strength Ring Groove Rivet

A high-strength ring groove rivet includes a gun head assembly, a driving mechanism, a transmission mechanism, a power source and a control module arranged in a riveting tool shell. The transmission mechanism has a planetary roller lead screw shaft in coaxial driving connection with the clamping jaw of the gun head assembly, and is also in driving connection with the driving shaft of the driving mechanism through gears installed on the planetary roller lead screw shaft and the driving shaft of the driving mechanism respectively. The planetary roller lead screw is adopted as a component for converting rotary motion into linear motion, the output tension can reach 70 kN, and riveting installation of ring groove rivets with the diameter specification of 12 mm can be effectively completed.

TECHNICAL FIELD

The present utility model belongs to the technical field of riveting and fastening, particularly to the technical field of handheld cordless electric tool design and production, and especially relates to a riveting tool for a high-strength ring groove rivet.

BACKGROUND

Ring groove rivets are widely used in fields such as new energy, bridges, and steel structures. If hydraulic or pneumatic tools are used, they are limited by on-site operating conditions, such as high altitude and high-voltage power supply. These tools are often difficult to meet the working conditions. If cordless charging electric riveting tools can be used for installation, these problems can be better solved. Currently, the output tension of electric riveting tools at home and abroad is below 30 kN, which cannot meet the installation requirements of large diameter ring groove rivets.

SUMMARY

The present utility model discloses a riveting tool for a high-strength ring groove rivet according to the defects of the prior art. The present utility model provides a riveting tool that can overcome the defects of existing riveting tools in riveting high-strength ring groove rivets, and adopts a movable electric drive, with a maximum riveting force of 70 kN, and can control different riveting methods.

The present utility model is implemented by the following technical solution:

A riveting tool for a high-strength ring groove rivet, comprising a gun head assembly, a driving mechanism, a transmission mechanism, a power source and a control module which are arranged in a riveting tool shell,wherein the gun head assembly comprises a clamping jaw and an anvil for squeezed riveting of a ring groove rivet;the power source is a detachable and rechargeable battery;the driving mechanism comprises a DC motor, a reduction gearbox driven by the motor, and a driving shaft;the transmission mechanism is a planetary roller lead screw transmission mechanism, a planetary roller lead screw shaft of the planetary roller lead screw transmission mechanism is in coaxial driving connection with the clamping jaw of the gun head assembly, and the planetary roller lead screw shaft is in driving connection with the driving shaft of the driving mechanism through gears installed on the planetary roller lead screw shaft and the driving shaft of the driving mechanism respectively.

Furthermore, the planetary roller lead screw shaft is driven parallel to the driving shaft.

Furthermore, the transmission mechanism further comprises a planetary roller lead screw nut which is in driving fit with the planetary roller lead screw shaft, and a large gear is sleeved on the periphery of the planetary roller lead screw nut; the diameter of a pinion sleeved on the driving shaft of the driving mechanism is smaller than that of a large gear, and the pinion sleeved on the driving shaft is in driving connection with the large gear sleeved on the planetary roller lead screw nut.

Furthermore, a planar thrust roller bearing is arranged on a front end face of the planetary roller lead screw nut, a needle roller thrust bearing is arranged on a rear end face, and a set of needle roller bearings is arranged before and behind the periphery respectively.

A set of needle roller bearings is arranged before and behind the periphery of the driving shaft respectively.

The control module of the present utility model comprises: an STM32 main controller circuit, a current sampling circuit, a brushless DC motor drive circuit, a Hall stroke protection circuit, an overcurrent protection circuit, a Hall limit circuit, and a blocking protection circuit.

For the riveting tool of the present utility model, the output tension can reach 70 kN, and riveting installation of ring groove rivets with the diameter specification of 12 mm can be effectively completed; the present utility model is provided with a man-machine interaction interface, so that riveting installation modes can be selected according to rivets of different specifications and models; The torque of the motor can be controlled by adjusting the input current of the motor, and finally the output tension of the tool is adjusted.

The drive and its transmission structure of the present utility model adopt the planetary roller lead screw as a component for converting rotary motion into linear motion; the planetary roller lead screw is used in design of handheld lithium battery riveting tools, and the riveting force is adjusted using a current control program. Compared to the ball screw used in conventional electric tools, the planetary roller lead screw shaft is in line contact with the lead screw nut, while the ball screw shaft is in point contact with the lead screw nut. Line contact has better stress than point contact. For two types of lead screws with the same diameter specification, the planetary roller lead screw can theoretically achieve three times the load capacity and six times the service life of ordinary ball screws. So, in the design of high tension electric riveting tools, using planetary roller lead screws with smaller diameter specifications can meet the design requirements and effectively reduce the weight of the entire machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present utility model will be further described below in conjunction with the detailed description. The detailed description is a further explanation of the principle of the present utility model, and does not limit the present utility model in any way. The same or similar technology as the present utility model does not exceed the scope of protection of the present utility model.

Refer to the figures.

The riveting tool for a high-strength ring groove rivet in the present utility model is driven by its own battery, comprising a gun head assembly, a driving mechanism, a transmission mechanism, a power source, etc.

The gun head assembly comprises a clamping jaw1and an anvil2; the anvil2is fixed with a gun body outer sleeve3, and the clamping jaw1is in transmission connection with the transmission mechanism. The power source can be provided by a rechargeable lithium battery20.

The driving mechanism is a reduction motor18driven by the rechargeable lithium battery20. The transmission mechanism is a planetary roller lead screw transmission mechanism. The reduction motor18drives the planetary roller lead screw nut27to rotate through gear transmission, resulting in axial linear motion of the planetary roller lead screw shaft29to generate tension or thrust.

The present utility model adopts the planetary roller lead screw as a component for converting rotary motion into linear motion; the planetary roller lead screw is used in design of handheld lithium battery riveting tools, and the riveting force is adjusted using a current control program.

Compared to the ball screw drive used in electric tools, the ball screw and lead screw nut are in point contact; in the riveting tool of the present utility model, the planetary roller lead screw shaft29is in line contact with the lead screw nut27, and line contact has better stress than point contact; for two types of lead screws with the same diameter specification, the planetary roller lead screw can theoretically achieve three times the load capacity and six times the service life of ordinary ball screws. In the design of high tension electric riveting tools, using planetary roller lead screws with smaller diameter specifications in the present utility model can meet the design requirements and effectively reduce the weight of the entire machine.

The tool is provided with a man-machine interaction interface, so that riveting parameters can be set through the interface, such as current, riveting stroke.

The control module of the present utility model comprises an STM32 main controller circuit, a current sampling circuit, a brushless DC motor drive circuit, a Hall stroke protection circuit, an overcurrent protection circuit, a Hall limit circuit, and a blocking protection circuit.

The present utility model can achieve riveting control based on the riveting principles and riveting characteristics of different rivets.

As shown inFIGS.3to6, in response to the fluctuation and low accuracy of the current collection circuit during the operation of the motor, as well as the riveting characteristics of short tail type ring groove rivets, the riveting tool in the present utility model is used to set a current value Ia and a time t in the riveting control of short tail type ring groove rivets. For example, for 12 mm rivet riveting, the current value Ia is set to 27 A and the time t is 0.8 s; the current sampling circuit outputs the collected current value Ib to the MCU main controller. When Ia>Ib, the motor is controlled to continue running at a constant power for t time. After the time is reached, the motor starts to brake and reverse, thus achieving precise riveting control. Compared to the direct control stroke method, the advantage of the riveting tool in the present utility model is that: it can determine whether the anvil is too worn based on the riveting effect, or whether the rivets are qualified.

As shown inFIGS.7to10, for the breakaway type ring groove rivets, due to their different riveting compositions and characteristics, the current change curves presented by the breakaway type ring groove rivets are different. The current is a discrete variation, and when broken away, its current value decreases instantly. Therefore, based on the change in current value, it can be determined whether the rivet is pulled apart, thereby achieving the goal of quickly controlling the motor brake reversal and achieving automatic reversal after breaking away.

The working process of the riveting tool in the present utility model is: after pressing the start switch21, the motor18is powered on and starts running, and the torque is increased through the deceleration of the gearbox22. The planetary roller lead screw nut27is installed with a large gear9, which is meshed with the pinion24on the gearbox22shaft to further reduce the speed and increase the torque of the lead screw nut27. The pinion24rotates to drive the large gear9to rotate and drive the planetary roller lead screw nut27to rotate. The rotational motion is converted into a linear motion of the planetary roller lead screw shaft29through the planetary roller lead screw, resulting in a tension on the clamping jaw1. This tension acts on the ring groove rivet, and the forces act on each other, causing the anvil2on the gun head to generate thrust and squeeze the collar for deformation. When the system detects that the current of motor18has reached the preset value, the control module sends a signal and starts timing until the preset conditions in the program are met, and then the motor18brakes and reverses to the initial state, completing a riveting cycle.

Before using the riveting tool, the lithium battery20is installed on the base of the electric riveting tool, and then a program is selected on the parameter setting page according to the rivets to be installed. The switch21is pressed to install the ring groove rivets.

When performing riveting operations, the corresponding riveting mode is selected first according to different rivets using the key17; the clamping jaw1is inserted into the tail part of the rivet, so that the pull trough inside the clamping jaw1is engaged with that at the tail part of the rivet; the switch21button is pressed, and then the motor18is powered on and starts running; upon power transmission by the driving mechanism and the transmission mechanism, the planetary roller lead screw shaft generates a tension F in the direction indicated by the arrow; the planetary roller lead screw shaft29is in threaded connection with the connecting shaft4, and the other end of the connecting shaft4is connected with the clamping jaw1. During this process, when the clamping jaw1is engaged and pulls the rivet tail and moves upwards, the anvil2presses against the outer edge of the collar, causing it to move in the opposite direction to clamping jaw1and squeeze the surface of the collar. In the process of squeezing the collar, the force required by the anvil2to squeeze the collar and achieve a certain deformation is the riveting force, which is equal to the tension generated by the planetary roller lead screw shaft29. The riveting force changes in real time and gradually increases. The current of the motor18during the riveting process is detected by the current detection sensor on the motor driving circuit board13, and the detected current value is fed back to the PLC program for data judgment. When the detected current value I or time t meets the set riveting mode, the motor immediately brakes and reverses. The downward movement of the planetary roller lead screw shaft29causes the clamping jaw1to push the rivet away from the jaw head1, while the anvil2is also detached from the collar, thus completing the installation of the rivet.