Fatigue test equipment and method for riveting tool

Abstract

The invention discloses fatigue test equipment and method for a riveting tool. Comprising a damping load system used for providing a load and used for simulating the stress condition during riveting of a snap rivet, the instant condition of snap of the snap rivet is simulated through the instant release effect of magnetic attraction force generated by an electromagnet, the whole tension system is monitored in real time through a pressure sensor, and the electromagnet can test the tensile force of the snap rivet according to test requirements. The electromagnets with different magnetic attraction forces are selected, when simulation starts, the damping load system is compressed successively along with increase of riveting force, and when the tension detected by the pressure sensor reaches the test requirement, the control system controls the electromagnet system to lose power, and the magnetic attraction forces generated by the electromagnets are released instantly. Therefore, the stress condition of the snapping type rivet during riveting can be simulated. According to the method, the stress condition during riveting of the snapping type rivet can be simulated, more importantly, impact vibration at the snapping moment can be simulated, and the problem that an existing snapping type riveting tool cannot be subjected to fatigue testing is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of riveting and fastening, and relates to a fatigue testing technology of a tool, in particular to a device and a method for fatigue testing a riveting tool. Background Art

[0002] In the field of fastener riveting, electric tools tend to gradually replace hydraulic and pneumatic tools, and the convenience of electric tools is more easily accepted by users. The development of electric tools inevitably requires fatigue testing to meet the higher needs of users. Existing riveting tool fatigue testing equipment can only perform fatigue testing of the maximum tensile force. However, in some sub-sectors, such as break-off fasteners, due to their unique break-off impact problem, there is currently almost no testing equipment for this type of riveting tool, including fatigue testing in the break-off state. Summary of the invention

[0003] The present invention discloses a fatigue test device and method for riveting tools in view of the deficiencies of the prior art. The present invention aims to provide a fatigue test device and method for riveting tools including a breaking state, which is closer to the actual working conditions and the tested life is closer to the actual life.

[0004] The present invention is achieved through the following technical solutions:

[0005] A fatigue testing device for riveting tools, characterized by comprising:

[0006] A test platform with a planar structure;

[0007] A tool fixing device is fixedly arranged on the test platform and is used to fix the riveting tool on one side of the platform; the riveting tool is connected and fixed to the left side force rod, and the end of the left side force rod is connected to a magnetic iron plate vertically arranged on the plate surface;

[0008] An infrared sensor is arranged on the test platform below the left stress-bearing rod, and a detachable positioning pin is arranged on the left stress-bearing rod at a corresponding position;

[0009] A damping load system is arranged on the other side of the test platform, the damping load system includes a load mechanism and a buffer mechanism and is fixed to the test platform through a second plate; the second plate is a flat plate with at least one through hole at the center of the plate surface, the lower side of which is fixed to the test platform and arranged perpendicularly to the force-bearing rod;

[0010] A load mechanism is arranged on the outer side of the second plate, and a buffer mechanism is arranged on the inner side; the load mechanism is a preload rebound mechanism; the central axis of the preload rebound mechanism freely passes through the central hole of the second plate and is vertically connected to the baffle on the other side of the second plate; a spring with two ends respectively connected and fixed to the second plate and the baffle on the central axis between the second plate and the baffle constitutes a damping buffer mechanism;

[0011] The center of the plate surface on the other side of the baffle of the buffer mechanism is connected to a fixed electromagnet through a right force-bearing rod, a tension sensor is connected between the baffle and the electromagnet, the other end face of the electromagnet is vertically arranged and parallel to the plate surface of the magnetic iron plate, and the electromagnet and the iron plate can be magnetically attracted and separated from each other;

[0012] The center of the first plate, the center of the second plate, the left stress rod, the right stress rod, the central axis and the riveting tool are arranged horizontally on the same axial line; and also includes a control system connected with the riveting tool, the infrared sensor, the electromagnet and the tension sensor.

[0013] The pre-compression rebound mechanism of the load mechanism of the present invention adopts a spring group pre-compression rebound mechanism, a cylinder or an oil cylinder.

[0014] A gas cylinder or oil cylinder is used, which is fixed on the second plate surface, and a piston is coaxially connected and fixed with a central axis and then passes through the central hole of the second plate.

[0015] A spring group preload rebound mechanism is adopted, which includes a plate one, several connecting shafts, and several springs; the plate one is vertically arranged and parallel to the plate two, and the center of the plate one is connected and fixed with the central shaft passing through the central hole of the plate two; several connecting shafts are evenly spaced around the central shaft and are arranged parallel to the central shaft, the outer end of each connecting shaft is connected and fixed with the plate one, and the inner end of each connecting shaft is respectively slidably matched through the through holes arranged on the plate two; springs are mounted on the central shaft and each connecting shaft.

[0016] The sleeve springs on the connecting shafts are nonlinear stiffness springs, or butterfly springs, or a combination of nonlinear stiffness springs and butterfly springs.

[0017] Furthermore, the tension sensor signal transmits data to the control system through the acquisition circuit, which is used to detect the tension situation of the entire process in real time; the tension sensor and its acquisition circuit auxiliary components are wrapped with magnetic shielding materials to avoid the influence of strong magnetism on the sensor.

[0018] Furthermore, the electromagnet is controlled by a power supply circuit and an AC relay control circuit; the tension collection of the tension sensor is realized by a power supply circuit and a differential sampling circuit; the logic control of the riveting tool controls the riveting tool switch through a DC relay; the human-computer interaction realizes data display and parameter setting, including starting and shutting down the test tool, starting and shutting down the electromagnet system, displaying the tension data curve, setting the single maximum tension, and counting the number of fatigue tests.

[0019] The present invention also discloses a method for fatigue testing of riveting tools, using the above fatigue testing equipment, comprising the following steps:

[0020] S1, the system is powered on, the electromagnet is started first, the electromagnet is energized to generate magnetic attraction, and is connected to the magnetic attraction plate through magnetic attraction;

[0021] S2, start the riveting tool, the controller controls the riveting tool to start working, the riveting tool pulls each force rod and the central axis to move, drives the initial point positioning pin to move backward, and the infrared sensor output signal is 0;

[0022] S3, the load mechanism starts to compress and the buffer mechanism starts to stretch, and the tension sensor monitors and records the tension value in real time; when the detected tension value is less than or equal to the pull-off force of the magnetic attraction, the controller controls the electromagnet relay to disconnect, the electromagnet loses power, the magnetic attraction is released instantly, the electromagnet and the magnetic attraction plate are disconnected instantly, and the test quantity count is increased by 1;

[0023] S4, after disconnection, the electromagnet rebounds to its initial position due to the compression of the load mechanism spring and the retraction of the buffer mechanism after stretching, and the test quantity count is increased by 1;

[0024] S5. After balancing, the control system controls the riveting tool to start reverse movement forward to the initial position. When the initial point positioning pin retreats to be perpendicular to the infrared sensor, the infrared sensor outputs a signal of 1, indicating that the riveting tool has retreated to its original position.

[0025] S6. Repeat S1 to S6 to carry out the next tensile test until the fatigue test is completed.

[0026] The benefit of the invention: There is no fatigue test tool for the break-off type riveting tool at present. The invention simulates the break-off working condition of the break-off type rivet by utilizing the characteristics of the electromagnet, and can realize the fatigue test simulation of the break-off type riveting tool, which simulates the actual working condition more closely, greatly improves the tool life and reduces the tool development cycle.

[0027] The control method proposed by the present invention based on the hardware enables each component to work reasonably and controls the breaking force at the same time, thereby meeting the fatigue test of different types of breaking tools.

[0028] The present invention performs fatigue testing on a pull-off type riveting tool. The unique method provided by the present invention can simulate the situation at the moment when the rivet is pulled off. The fatigue test is closer to the actual working condition, and the tested life is closer to the actual life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the fatigue testing equipment of the present invention;

[0030] Figure 2 This is a system control flow chart of the fatigue test method of the present invention;

[0031] Figure 3 This is a diagram of the human-machine interaction interface of the fatigue test equipment of the present invention;

[0032] Figure 4This is a schematic diagram of the circuit structure of the fatigue testing equipment of the present invention.

[0033] In the figure, 101 is plate one, 102 is a spring, 103 is plate two, 104 is a buffer mechanism, 105 is a baffle, 106 is a tension sensor, 107 is a right force rod, 108 is an electromagnet, 109 is a magnetic iron plate, 110 is a tool fixing device, 111 is a control system and a human-computer interaction interface, 112 is a riveting tool, 113 is a test platform, 114 is a connecting shaft, 115 is an infrared sensor, 116 is a positioning pin, 117 is a left force rod, and 118 is a central axis. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific implementation methods. The specific implementation methods are further descriptions of the principles of the present invention and do not limit the present invention in any way. Technologies that are the same or similar to the present invention do not exceed the scope of protection of the present invention.

[0035] Combined with the attached pictures.

[0036] As shown in the figure, the fatigue testing equipment for riveting tools in this embodiment includes a damping load system, an electromagnet 108 , a tension sensor 106 , a control system, a riveting tool 112 , and a testing platform 113 .

[0037] The damping load system includes a load mechanism and a buffer mechanism; the load mechanism is a preload rebound mechanism, which provides load force through a spring group preload rebound mechanism, a cylinder or a hydraulic cylinder; the electromagnet 108 provides magnetic attraction; the tension sensor 106 detects the tension data of the entire system through an acquisition circuit; the control system includes the control of the electromagnet 108, the data acquisition of the tension sensor 106, human-computer interaction and the logic control of the entire system; the riveting tool 112 is a tool that needs to be fatigue tested; the test platform 113 is a platform for fixing the above-mentioned systems.

[0038] The spring group preload rebound mechanism of the present invention includes a plate 101, a plate 2 103 and springs 102 of different lengths and different properties; the load system provides the required load, and different types of springs 102 can be selected according to the product performance curve to be tested, such as a nonlinear stiffness spring or a butterfly spring combination, to ensure that the simulated force curves are similar.

[0039] By choosing to pull the air cylinder or hydraulic cylinder, the effect of simulating load can also be achieved.

[0040] The spring group preload rebound mechanism of the load mechanism of this embodiment is composed of two plates and multiple springs, which are placed at one end of the entire test platform 113. The spring 102 is placed between the plate 101 and the plate 2 103. A connecting rod 114 passes through the middle of each spring 102. Multiple connecting rods 114 are arranged in parallel and spaced between the plate 101 and the plate 2 103. The length of each connecting rod 114 is greater than the spacing between the two plates. One end of the connecting rod 114 is fixed to the plate 101 by bolts, and the other end passes through the through hole on the plate 2 103 and cooperates with the sliding support of the plate 2 103; the central axis 118 passes through the through hole in the center of the plate 2 103 and is fixedly connected to the center of the plate 1 101. The connecting rods 114 and the springs 102 set thereon are evenly spaced and arranged around; the bottom support of the plate 2 103 is fixed on the test platform 113, and the bottom of the plate 101 is suspended and movable.

[0041] There is a buffer device 104 between the second plate 103 and the tension sensor 106. The buffer device 104 includes a telescopic spring; the spring is sleeved on the central axis 118, one end of the spring is fixedly connected to the support of the second plate 103, and the other end is fixedly connected to the support of the baffle 105 fixedly arranged on the central axis. The buffer device 104 is used to buffer the impact generated when the magnetic attraction disappears and the spring rebounds, so that the system can be quickly stabilized.

[0042] In this embodiment, the tension sensor 106 is placed between the electromagnet 108 and the baffle 105, and the centers of both ends are connected and fixed to the left force rod 107, and each connection piece ensures that they are in the same horizontal position. The signal of the tension sensor 106 transmits data to the controller system through the acquisition circuit, which is used to detect the tension of the whole process in real time, and the tension sensor 106 and its acquisition circuit auxiliary components are wrapped with magnetic shielding materials to avoid the influence of strong magnetism on the sensor.

[0043] In this embodiment, the electromagnet 108 has a magnetic attraction force, one end of which is connected to the riveting tool 112 through the magnetic attraction plate 109. The electromagnet 108 is disconnected from the magnetic attraction plate 109 when it is not powered on, and the other end is connected to the tension sensor 106 through the left force rod 107. Electromagnets 108 of different specifications can be used, and their magnetic attraction force is usually equal to the breaking force of the riveted nail riveted by the riveting tool 112 to be tested. When the tension value detected by the tension sensor 106 is greater than the set value, the magnetic attraction force of the electromagnet 108 is instantly released to achieve the simulation of the rivet breaking.

[0044] The center of the first plate 101, the center of the second plate 103, the left stress rod 107, the right stress rod 117, the central axis 118, and the riveting tool 112 are arranged horizontally on the same axial line.

[0045] The test platform 113 is a fixing device, and the plate 2 103, the tool fixing device 110, and the infrared sensor 115 are fixedly installed on the test platform 113, while the plate 101 and the electromagnet 108 are in a relatively active state with the test platform 113. At the same time, the riveting tool 112 is fixed on the tool fixing device 110, and the front end of the tool is connected to the magnetic iron plate 109 through the right force rod 117.

[0046] The initial point positioning pin 116 is installed on the right side force bearing rod 117, which adopts a movable connection to facilitate the adjustment of the initial point position of the riveting test tool 112.

[0047] The control system includes control of the electromagnet 108 , collection of tension by the tension sensor 106 , human-computer interaction 111 and logic control of the riveting tool 112 .

[0048] The electromagnet 108 is controlled by a power supply circuit and an AC relay control circuit. The tension collection of the tension sensor 106 is composed of a power supply circuit and a differential sampling circuit. The logic control of the riveting tool 112 is controlled by controlling the switch of the riveting tool 112, and the DC relay is used to control the switch of the riveting tool 112. The control system and the human-computer interaction interface 111 are for displaying data and setting related parameters.

[0049] The human-machine interaction system control includes the start and stop of the riveting tool 112, the start and stop of the electromagnet 108, the display of the tension data curve, the single maximum tension setting, and the fatigue test number counting. The single maximum tension is the maximum tension when the electromagnet 108 is disconnected from the magnetic iron plate 109, and the fatigue test number counting is increased by one time each time the controller controls the electromagnet 108 system to disconnect.

[0050] The fatigue testing method of the present invention comprises the following steps:

[0051] S1, the system is powered on, and the electromagnet 108 is first started. The electromagnet 108 is energized to generate magnetic attraction, and is connected to the magnetic attraction plate 109 through the magnetic attraction;

[0052] S2, start the riveting tool 112, the controller controls the riveting tool 112 to start working, the riveting tool 112 pulls each force-bearing rod and the central axis 118 to move, drives the initial point positioning pin 116 to move backward, and the infrared sensor 106 outputs a signal of 0;

[0053] S3, the load mechanism starts to compress, the buffer mechanism 104 starts to stretch, and the tension sensor 106 monitors and records the tension value in real time; when the detected tension value is less than or equal to the pull-off force of the magnetic attraction, the controller controls the electromagnet 108 relay to disconnect, the electromagnet 108 loses power, the magnetic attraction is released instantly, the electromagnet 108 and the magnetic attraction plate 109 are disconnected instantly, and the test quantity count is increased by 1;

[0054] S4, after disconnection, the electromagnet 108 rebounds to its initial position due to the compression and rebound of the load mechanism spring 102 and the stretch and retraction of the buffer mechanism 104, and the test quantity count is increased by 1;

[0055] S5. After balancing, the control system controls the riveting tool 112 to start reverse movement forward to the initial position. When the initial point positioning pin 116 retreats to be perpendicular to the infrared sensor 115, the infrared sensor 115 outputs a signal of 1, indicating that the riveting tool 112 has retreated to its original position.

[0056] S6. Repeat S1 to S6 to carry out the next tensile test until the fatigue test is completed.

[0057] The fatigue test method of the riveting tool of the present invention is described below with reference to the accompanying drawings. Figure 1 As shown, the system is powered on, and the control system starts the electromagnet 108 and the riveting tool 112 control switches in sequence. The electromagnet 108 is powered on first to generate magnetic attraction, and the magnetic attraction plate 109 is attracted and connected. At this time, the infrared sensor 115 outputs a signal of 1, and then the riveting tool 112 switch is closed, riveting starts, and the riveting tool 112 pulls the right force rod 117 to move backward. At this time, the infrared sensor 115 outputs a signal of 0.

[0058] Since the electromagnet 108 and the magnetic iron plate 109 are in a magnetic connection state, the left force rod 107 pulls the electromagnet 108 and the tension sensor 106 to move backward. The left force rod 107 is connected to the central axis 118 and the damping load system. The plate 2 103 is fixedly connected to the test platform 113. The central axis 118 pulls the plate 1 111 to move backward. At this time, the load mechanism gradually begins to compress to provide the load. When the tension value detected by the tension sensor 106 is close to the pull-off force of the electromagnet 108 and the magnetic iron plate 109, the controller controls the AC relay to disconnect. At this time, the electromagnet 108 loses power, the magnetic attraction disappears, and the electromagnet 108 and the magnetic iron plate 109 are instantly disconnected. At this time, the force on the riveting tool 112 is similar to the moment when the rivet is pulled off.

[0059] Then, the electromagnet 108 rebounds under the influence of the compression force of the spring 102 and moves forward instantly. By compressing the buffer device 104, the damping load system, the electromagnet 108, and the tension sensor 106 end gradually tend to balance; when the riveting tool 112 detects the speed change, it controls the motor to reverse to the starting position. At this time, the infrared sensor 115 outputs a signal of 1, indicating that the riveting tool 112 has retreated to the starting point;

[0060] The test was started again, and the control system controlled the electromagnet 108 to be powered on again to generate magnetic attraction, firmly attracting the magnetic plate 109, and then controlled the switch of the riveting tool 112 to be closed, pulling the right force rod 117, the magnetic plate 109, the electromagnet 108, the left force rod 107, the tension sensor 106, the baffle 105, the center axis 118, and the plate 111 to move backward and compress, and the fatigue test was carried out reciprocatingly.

Claims

1. A fatigue testing device for riveting tools, characterized in that include: A test platform with a planar structure; A tool fixing device is fixedly arranged on the test platform and is used to fix the riveting tool on one side of the platform; the riveting tool is connected and fixed to the left side force rod, and the end of the left side force rod is connected to a magnetic iron plate vertically arranged on the plate surface; An infrared sensor is arranged on the test platform below the left stress-bearing rod, and a detachable positioning pin is arranged on the left stress-bearing rod at a corresponding position; A damping load system is arranged on the other side of the test platform, the damping load system includes a load mechanism and a buffer mechanism and is fixed to the test platform through a second plate; the second plate is a flat plate with at least one through hole at the center of the plate surface, the lower side of which is fixed to the test platform and arranged perpendicularly to the force-bearing rod; A load mechanism is arranged on the outer side of the second plate, and a buffer mechanism is arranged on the inner side. The load mechanism is a preload rebound mechanism. The central axis of the preload rebound mechanism freely passes through the central hole of the second plate and is vertically connected to the baffle on the other side of the second plate. A spring with two ends respectively connected and fixed to the second plate and the baffle is mounted on the central axis between the second plate and the baffle to form a buffer mechanism. The center of the plate surface on the other side of the baffle of the buffer mechanism is connected to a fixed electromagnet through a right force-bearing rod, a tension sensor is connected between the baffle and the electromagnet, the other end face of the electromagnet is vertically arranged and parallel to the plate surface of the magnetic iron plate, and the electromagnet and the iron plate can be magnetically attracted and separated from each other; The center of the first plate, the center of the second plate, the left stress rod, the right stress rod, the central axis and the riveting tool are arranged horizontally on the same axial line; and also includes a control system connected with the riveting tool, the infrared sensor, the electromagnet and the tension sensor.

2. The fatigue testing device for riveting tools according to claim 1, characterized in that: The preload rebound mechanism of the load mechanism is a spring group preload rebound mechanism, a cylinder or an oil cylinder.

3. The fatigue testing device for riveting tools according to claim 2, characterized in that: The air cylinder or oil cylinder is fixed on the second plate surface, and the piston is coaxially connected and fixed with the central axis and then passes through the central hole of the second plate.

4. The fatigue testing device for riveting tools according to claim 2, characterized in that: The spring group preload rebound mechanism includes a plate one, several connecting shafts, and several springs; the plate one is vertically arranged and parallel to the plate two, and the center of the plate one is connected and fixed to the central shaft passing through the central hole of the plate two; several connecting shafts are evenly spaced around the central shaft and are arranged parallel to the central shaft, the outer end of each connecting shaft is connected and fixed to the plate one, and the inner end of each connecting shaft slides through the through holes set on the plate two; springs are mounted on the central shaft and each connecting shaft.

5. The fatigue testing device for riveting tools according to claim 4, characterized in that: The sleeve springs on the connecting shafts are nonlinear stiffness springs, or butterfly springs, or a combination of nonlinear stiffness springs and butterfly springs.

6. The fatigue testing device for riveting tools according to claim 2, 3, 4 or 5, characterized in that: The tension sensor signal transmits data to the control system through the acquisition circuit, which is used to detect the tension situation of the whole process in real time; the tension sensor and its acquisition circuit auxiliary components are wrapped with magnetic shielding materials to avoid the influence of strong magnetism on the sensor.

7. The fatigue testing device for riveting tools according to claim 6, characterized in that: The electromagnet is controlled by a power supply circuit and an AC relay control circuit; the tension collection of the tension sensor is realized by a power supply circuit and a differential sampling circuit; the logic control of the riveting tool controls the riveting tool switch through a DC relay; the human-computer interaction realizes data display and parameter setting, including starting and shutting down the test tool, starting and shutting down the electromagnet system, displaying the tension data curve, setting the single maximum tension, and counting the number of fatigue tests.

8. A method for fatigue testing of riveting tools, characterized in that: The fatigue testing device according to any one of claims 1 to 7 comprises the following steps: S1, the system is powered on, the electromagnet is started first, the electromagnet is energized to generate magnetic attraction, and is connected to the magnetic attraction plate through magnetic attraction; S2, start the riveting tool, the controller controls the riveting tool to start working, the riveting tool pulls each force rod and the central axis to move, drives the initial point positioning pin to move backward, and the infrared sensor output signal is 0; S3, the load mechanism starts to compress and the buffer mechanism starts to stretch, and the tension sensor monitors and records the tension value in real time; when the detected tension value is less than or equal to the pull-off force of the magnetic attraction, the controller controls the electromagnet relay to disconnect, the electromagnet loses power, the magnetic attraction is released instantly, the electromagnet and the magnetic attraction plate are disconnected instantly, and the test quantity count is increased by 1; S4, after disconnection, the electromagnet rebounds to its initial position due to the compression of the load mechanism spring and the retraction of the buffer mechanism after stretching, and the test quantity count is increased by 1; S5. After balancing, the control system controls the riveting tool to start reverse movement forward to the initial position. When the initial point positioning pin retreats to be perpendicular to the infrared sensor, the infrared sensor outputs a signal of 1, indicating that the riveting tool has retreated to its original position. S6. Repeat S1 to S6 to carry out the next tensile test until the fatigue test is completed.

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