JP2018040751A - Fatigue/endurance test apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fatigue/endurance test apparatus capable of safely performing a fatigue/endurance test.SOLUTION: A fatigue/endurance test apparatus comprises a motor 11, a ball screw 13 rotated by drive of the motor 11, a nut 14 screwed onto the ball screw 13, and a hollow piston 18 coupled together to the nut 14. The ball screw 13, the piston 18, and the like are housed in a tubular casing 10, and the casing 10 is stored with lubricant therein. A temperature sensor 15 for detecting a temperature of the lubricant stored in the casing 10 is disposed in a lid member 26. When the temperature of the lubricant detected by the temperature sensor 15 is a first setting temperature or more, any one of a low speed drive and an intermittent drive is performed, and when the temperature of the lubricant is a second setting temperature or more, a test is stopped.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fatigue / durability test apparatus for performing a fatigue test by vibrating a specimen such as a test piece or performing a durability test by vibrating a specimen such as a part.

  For example, in the transportation industry, centering on auto parts and finished car manufacturers, research and development of new materials and new mechanisms that are robust and lightweight are progressing, so the durability of various parts for the purpose of improving safety and reliability. There is a growing need for sex assessment. Conventionally, a fatigue / durability test apparatus equipped with a hydraulic servo mechanism has been used for such an endurance test. However, in the hydraulic fatigue / durability test apparatus, not only regular replacement of hydraulic oil and periodic replacement of valves are required, but also the occupied space becomes large.

  For this reason, in recent years, motor-driven fatigue / durability testing apparatuses are also frequently used. Such a fatigue / endurance test apparatus includes a motor, a ball screw that is rotated by driving the motor, a nut that is screwed to the ball screw, and a piston that is coupled to the nut, and rotational motion of the ball screw. Is converted into a reciprocating motion of the piston, thereby applying a load to the specimen.

  Patent Document 1 discloses an electric actuator that can also be used in a fatigue / endurance test apparatus. This electric actuator incorporates a spline outer cylinder, a ball screw nut and a hollow motor in a compound shaft having a ball spline groove on the outer peripheral surface of the ball screw shaft, and the hollow motor drive shaft is relative to the casing via a bearing. The motor body and the spline outer cylinder are fixed so as to be immovable in the axial and rotational directions with respect to the casing, and a ball screw nut is integrally connected to the end of the hollow motor drive shaft. The rotational driving force of the motor drive shaft is converted into the axial thrust of the composite shaft via the ball screw nut, and the composite shaft is moved linearly by supporting the axial reaction force of the thrust with the bearing of the hollow motor. The axial load acting on the bearing is loaded by the ball screw nut and the torque is supported by the spline cylinder, and the radial load and moment load in all directions are scanned. Outer cylinder for a line and doing supporting and positioning the ball screw nut.

  In this type of electric actuator, grease is used to lubricate the ball screw and nut. However, when the ball screw and the nut slide slightly because the ball screw reciprocates by a small angle, the grease is not sufficiently distributed to the sliding part due to the viscosity of the grease. There is. In addition, if the electric actuator is continuously driven at a high speed, heat is generated due to friction between the ball screw and the nut, and the surrounding temperature and thus the temperature of the entire electric actuator rises. May reach.

  For this reason, it is conceivable to measure the temperature of the ball screw or nut with a sensor and stop the apparatus when the temperature exceeds the allowable temperature. However, it is not easy to measure the temperature of a rotating ball screw or a reciprocating nut. For this reason, it is conceivable to arrange a temperature sensor in the vicinity of the ball screw or nut. However, it is difficult to measure the temperature of the ball screw or nut with such a sensor because the air has low thermal conductivity. is there.

  Patent Document 2 discloses an electric actuator that can be used for a vibration test. The electric actuator includes a lubricating oil filled in a case that accommodates a ball screw and a nut, and an elastic member that is accommodated in the case. According to this electric actuator, the ball screw and the nut are immersed in the lubricating oil, and both are always lubricated. Even if the output cylinder enters and exits in the case, the output cylinder can move smoothly due to the volume change of the elastic member, and even when the output cylinder expands and contracts with a small amplitude, fretting does not occur, and the electric actuator Can be prevented.

JP-A-6-300106 JP, 2006-54618, A

  According to the electric actuator described in Patent Document 2, sufficient lubrication is realized by the lubricating oil stored in the case, and the temperature rise of the ball screw and the nut can be suppressed by the lubricating oil.

  Here, in general, when a fatigue / endurance test is performed using a fatigue / endurance test apparatus, it is necessary to continuously perform a high-speed reciprocating motion over many days. In such a case, frictional heat is generated at the sliding part of the ball screw and nut, and this frictional heat accumulates over a long period of time, causing the ball screw or nut temperature to exceed the allowable temperature. There is. As described above, when the fatigue / durability test is continued in a state where the allowable temperature is exceeded, not only the ball screw and the nut are damaged, but there is a possibility of smoking or ignition. Such a phenomenon is a problem that may occur similarly when lubricating oil is stored in the case, as described in Patent Document 2.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fatigue / durability test apparatus capable of safely executing a fatigue / durability test.

  The invention according to claim 1 includes a motor, a ball screw that rotates by driving the motor, a nut that is screwed to the ball screw, and a piston that is coupled to the nut, and the rotational movement of the ball screw. Is a fatigue / endurance test apparatus that applies a load to a specimen by converting the piston into a reciprocating motion of the piston, the casing surrounding the ball screw and the nut and storing lubricating oil therein, and the casing A temperature detector that detects the temperature of the lubricating oil stored in the inside, and a control unit that controls the rotation of the motor based on the temperature of the lubricating oil detected by the temperature detector. And

  According to a second aspect of the present invention, in the fatigue / endurance test apparatus according to the first aspect, a rotation restricting mechanism for restricting rotation of the piston around the axis of the ball screw is provided outside the casing. .

  According to a third aspect of the present invention, in the fatigue / endurance test apparatus according to the second aspect, the rotation restricting mechanism is centered on a connecting member that reciprocates together with the piston, and an axis of the ball screw in the connecting member. A rotation restricting member for restricting the rotation, and a sensor for detecting a position of the connecting member during reciprocal movement.

  According to a fourth aspect of the present invention, in the fatigue / endurance test apparatus according to any one of the first to third aspects, the temperature of the lubricating oil detected by the temperature detector is equal to or higher than a set temperature. Then, the rotation of the ball screw is stopped.

  According to a fifth aspect of the present invention, in the fatigue / endurance test apparatus according to any one of the first to fourth aspects, the control unit is responsive to the temperature of the lubricating oil detected by the temperature detector. The rotation speed of the ball screw is changed or the ball screw is rotated intermittently.

  According to the first to fifth aspects of the invention, it is possible to detect that the temperature of the ball screw and the nut has risen via the lubricating oil by the temperature detector. For this reason, by stopping the rotation of the ball screw according to the temperature of the lubricating oil, or controlling the rotation of the ball screw, problems such as damage to the ball screw or nut or ignition are prevented, and fatigue and durability tests Can be executed safely.

  According to the second aspect of the present invention, it is possible to prevent rotation of the piston and the nut connected thereto without using a ball spline or the like. For this reason, it becomes possible to prevent the lubricating oil in the casing from leaking outside in the vicinity of the piston.

  According to invention of Claim 3, it becomes possible to recognize the position of a piston by detecting the position of the connection member in a rotation control mechanism.

1 is a schematic diagram of a fatigue / durability test apparatus according to the present invention. It is a block diagram which shows the main control systems of the fatigue / endurance test apparatus based on this invention. It is a schematic diagram of the fatigue and endurance test device concerning a 2nd embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a fatigue / durability test apparatus according to the present invention.

  The fatigue / durability test apparatus includes a motor 11, a ball screw 13 that rotates by driving the motor 11, a ball screw nut 14 that is screwed to the ball screw 13, and a hollow shape that is connected to the nut 14. The piston 18 is provided. The ball screw 13 and the piston 18 are accommodated in the cylindrical casing 10. And in this casing 10, lubricating oil is stored. Note that the amount of the lubricating oil is about 80% of the volume in the casing 10 in order to cope with the change in the volume in the casing 10 due to the reciprocating motion of the piston 18.

  An AC servo motor is employed as the motor 11. An encoder 31 described later is disposed inside the motor 11. The rotating shaft 12 of the motor 11 is connected to the ball screw 13 via a coupling 21 and a connecting shaft 19. The connecting shaft 19 is rotatably supported by a bearing 22. A lid member 26 having a hole through which the connecting shaft 19 can pass is disposed at one end of the casing 10. An oil seal 16 is disposed between the lid member 26 and the connecting shaft 19 to prevent the lubricating oil from leaking to the outside.

  The lid member 26 is provided with a temperature sensor 15 for detecting the temperature of the lubricating oil stored in the casing 10. As the temperature sensor 15, an electrical temperature sensor such as a thermistor, a resistance temperature detector, or a thermocouple can be used.

  An end portion of the ball screw 13 opposite to the motor 11 enters the hollow portion of the piston 18. The piston 18 is supported by the guide member 23 so as to be slidable in the axial direction (left-right direction in FIG. 1). The piston 18 is connected to the specimen 25 via the load cell 24. An oil seal 17 is disposed between the piston 18 and the guide member 23, and leakage of the lubricating oil to the outside is prevented.

  A connecting member 41 is disposed at one end of the outer region of the casing 10 in the piston 18. The connecting member 41 is connected to an end portion of a linear shaft 42 slidably supported by a linear bush 43 disposed outside the casing 10. By the action of the connecting member 41, the linear shaft 42, and the linear bush 43, the piston 18 and the nut 14 are restricted from rotating about the axis. By adopting such a rotation restricting mechanism, it is not necessary to dispose a ball spline or the like that causes leakage of the lubricating oil on the outer peripheral portion of the piston 18.

  A moving part 44 of the stroke sensor 32 is fixed to the linear shaft 42. In addition, a fixed portion 45 of the stroke sensor 32 is supported on the support portion 46 disposed on the outer peripheral portion of the casing 10. By detecting the movement amount of the connecting member 41 by the stroke sensor 32, the movement amount of the piston 18 can be detected.

  FIG. 2 is a block diagram showing a main control system of the fatigue / endurance test apparatus according to the present invention.

  This fatigue / endurance test apparatus includes a CPU as a processor that executes logical operations, a ROM that stores an operation program necessary for controlling the apparatus, a RAM that temporarily stores data during control, and the like. The control part 30 which controls is provided. The control unit 30 includes a motor 11, an encoder 31 for detecting the rotation state of the ball screw 13 by the motor 11, a load cell 24 for detecting a test force applied to the specimen 25, and the casing 10 Are connected to a temperature sensor 15 for detecting the temperature of the lubricating oil stored in the cylinder and a stroke sensor 32 for detecting the amount of movement of the piston 18. Further, the control unit 30 is connected to a warning unit 33 for displaying a warning display to be described later or generating a warning sound.

  When the fatigue test or the durability test is executed by the fatigue / durability test apparatus according to the present invention, the ball screw 13 is reciprocated in the clockwise direction and the counterclockwise direction by the drive of the motor 11. As the ball screw 13 rotates, the nut 14 reciprocates in the axial direction of the ball screw 13 (the left-right direction in FIG. 1). As a result, the piston 18 connected to the nut 14 reciprocates linearly, and a test load due to reciprocating vibration is applied to the specimen 25 via the load cell 24.

  The amount of displacement of the specimen 25 at this time is calculated by the control unit 30 based on the rotation state of the ball screw 13 detected by the encoder 31, and is also detected by the stroke sensor 32. In addition, the magnitude of the test load on the specimen 25 at this time is measured by the load cell 24 and transmitted to the control unit 30.

  When such a test is continuously performed, the temperature of the ball screw 13 and the nut 14 that slide with each other increases. However, in this fatigue / endurance test apparatus, the ball screw 13 and the nut 14 are cooled by the action of the lubricating oil stored in the casing 10. Since the heat generated by the ball screw 13 and the nut 14 can be radiated from the casing 10 to the atmosphere using the lubricating oil as a medium, the temperature rise of the ball screw 13 and the nut 14 can be suppressed. At this time, since the ball screw 13 and the nut 14 are immersed in the lubricating oil stored in the casing 10, sufficient lubrication is realized by this lubricating oil.

  The temperature of the ball screw 13 and the nut 14 is detected by the temperature sensor 15 through a lubricating oil having a high thermal conductivity. Then, the rotation of the ball screw 13 by the motor 11 is controlled according to the temperature of the lubricating oil detected by the temperature sensor 15. More specifically, in this fatigue / endurance test apparatus, when the temperature of the lubricating oil detected by the temperature sensor 15 becomes equal to or higher than the first set temperature, a low speed that reduces the rotational speed of the ball screw 13 by the motor 11. Either the operation or the intermittent operation of intermittently executing the rotation of the ball screw 13 by the motor is executed. In addition, the control unit 30 transmits a signal to the warning unit 33 to execute a warning that the temperature of the lubricating oil has reached the first set temperature by a warning display or a warning sound.

  Further, when the temperature of the lubricating oil further rises and becomes equal to or higher than the second set temperature that is higher than the first set temperature described above, the control unit 30 stops the rotation of the motor 11 to perform a fatigue test or durability. Stop the test. Further, the control unit 30 transmits a signal to the warning unit 33, and executes a warning that the temperature of the lubricating oil has reached the second set temperature and the test has been stopped by a warning display or a warning sound.

  In the case of adopting such a configuration, by controlling the rotation of the ball screw 13 according to the temperature of the lubricating oil, a fatigue test or a durability test is performed within a range in which the temperature of the ball screw 13 and the nut 14 does not rise excessively. It becomes possible to execute. Thereby, damage to ball screw 13 and nut 14 can be prevented. Further, when the temperature of the lubricating oil becomes even higher, the problem of smoke generation or ignition from the threaded portion of the ball screw 13 and the nut 14 can be prevented by stopping the test. For this reason, it becomes possible to perform a fatigue and an endurance test safely.

  In the above-described embodiment, either the low speed operation or the intermittent operation is performed when the temperature of the lubricating oil becomes equal to or higher than the first set temperature, and the temperature of the lubricating oil becomes equal to or higher than the second set temperature. However, the test may be stopped without performing low speed operation or intermittent operation.

  Next, another embodiment of the present invention will be described. FIG. 3 is a schematic view of a fatigue / endurance test apparatus according to the second embodiment of the present invention. In addition, about the member similar to 1st Embodiment mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the first embodiment described above, the temperature sensor 15 is disposed on the lid member 26. In the case of adopting such a configuration, when the fatigue / endurance test is executed in a state where the lid member 26 is disposed on the upper side, it becomes impossible to measure the temperature of the lubricating oil by the temperature sensor 15. . For this reason, in this 2nd Embodiment, it has the structure which has arrange | positioned the temperature sensor 15 near the center part of the casing 10. FIG.

  As described above, the amount of the lubricating oil is about 80% of the volume in the casing 10 in order to cope with the change in the volume in the casing 10 due to the reciprocating motion of the piston 18. For this reason, when such a configuration is employed, the temperature of the lubricating oil can be measured by the temperature sensor 15 even when the casing 10 is arranged in the vertical direction. Further, when the casing 10 is arranged in the horizontal direction, the temperature of the lubricating oil can be measured by the temperature sensor 15 by adjusting the angular position around the axis of the casing 10.

  For example, the temperature of the lubricating oil can be measured with any one of the temperature sensors 15 by using a plurality of temperature sensors 15 such as disposing the temperature sensor 15 at both positions shown in FIGS. A configuration may be adopted.

DESCRIPTION OF SYMBOLS 10 Casing 11 Motor 12 Rotating shaft 13 Ball screw 14 Nut 15 Temperature sensor 16 Oil seal 17 Oil seal 18 Piston 22 Bearing 23 Guide member 24 Load cell 25 Specimen 30 Control part 31 Encoder 32 Stroke sensor 33 Warning part 41 Connecting member 42 Linear shaft 43 Linear bushing

Claims (5)

A motor, a ball screw that is rotated by driving the motor, a nut that is screwed to the ball screw, and a piston that is coupled to the nut, and converts the rotational motion of the ball screw into the reciprocating motion of the piston. A fatigue / durability test device for applying a load to the specimen by
A casing that encloses the ball screw and the nut and stores lubricating oil therein;
A temperature detector for detecting the temperature of the lubricating oil stored in the casing;
Based on the temperature of the lubricating oil detected by the temperature detector, a control unit that controls the rotation of the motor;
Fatigue / endurance test equipment characterized by comprising In the fatigue / durability test apparatus according to claim 1,
A fatigue / endurance test apparatus provided with a rotation restricting mechanism for restricting rotation of the piston around the axis of the ball screw on the outside of the casing. In the fatigue / endurance test apparatus according to claim 2,
The rotation restricting mechanism includes a connecting member that reciprocates together with the piston, and a rotation restricting member that restricts rotation of the connecting member around the axis of the ball screw.
A fatigue / durability test apparatus further comprising a sensor for detecting a position of the connecting member during reciprocal movement. In the fatigue / endurance test apparatus according to any one of claims 1 to 3,
The control unit is a fatigue / durability test apparatus that stops the rotation of the ball screw when the temperature of the lubricating oil detected by the temperature detector becomes equal to or higher than a set temperature. In the fatigue / endurance test apparatus according to any one of claims 1 to 4,
The controller is a fatigue / endurance test apparatus that changes a rotation speed of the ball screw or intermittently rotates the ball screw according to the temperature of the lubricant detected by the temperature detector.

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