Ball screw device testing device
The test apparatus for ball screw devices addresses the need for cost-effective torque control by using controllable motors and an elastic body to adjust axial load based on stroke, reducing expenses and maintaining consistent or varying loads.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NSK LTD
- Filing Date
- 2025-08-19
- Publication Date
- 2026-06-18
Smart Images
Figure JP2025029020_18062026_PF_FP_ABST
Abstract
Description
Test apparatus for ball screw device 【0001】 The present disclosure relates to a test apparatus for a ball screw device. 【0002】 A ball screw device is a device that converts rotational motion into linear motion or converts linear motion into rotational motion. In order to confirm the operation of this ball screw device and evaluate its efficiency, a test apparatus for a ball screw device has been conventionally used. As an example of a test apparatus for a ball screw device, those described in the following patent documents can be cited. In the following, the test apparatus for a ball screw device may sometimes be simply referred to as a test apparatus. 【0003】 The test apparatus described in the following patent documents includes a load device that applies an axial load (hereinafter referred to as an axial load) to the ball screw device. The load device includes a motor and a load-side ball screw device that converts the torque generated by the motor into an axial load. 【0004】 Japanese Patent Application Laid-Open No. 2003-294581, Patent No. 7572899 【0005】 According to the above test apparatus, the axial load is increased or decreased by controlling the torque of the motor of the load device. By the way, it is possible to control the torque to be constant with an inexpensive motor, but an expensive motor is used when realizing arbitrary torque control. In recent years, a test apparatus that uses an inexpensive motor whose output shaft position can be controlled instead of an expensive motor capable of arbitrary torque control has been desired. It is also desired to be able to adjust the axial load corresponding to the stroke of the ball screw device to be tested. 【0006】 The present disclosure has been made in view of the above, and an object thereof is to provide a test apparatus for a ball screw device that uses a motor capable of controlling the position of the output shaft and can adjust the axial load corresponding to the stroke of the ball screw device. 【0007】To achieve the above objective, a test apparatus for a ball screw device according to one aspect of the present disclosure includes: a support portion that rotatably supports one of the first rotating parts of the screw shaft and nut of the ball screw device to be tested, and linearly supports the other first linear part; a first motor that is positioned in a first direction which is one of the axial directions parallel to the central axis of the screw shaft as viewed from the support portion, and generates torque to rotate the first rotating part; and a load device that is positioned in a second direction which is the other of the axial directions as viewed from the support portion, and contacts the first linear part to apply an axial load to the first linear part. The load device includes a load-side ball screw device having a second motor, a second rotating part that rotates by the torque generated by the second motor, and a second linear part that moves linearly by the rotation of the second rotating part, and an elastic body interposed between the first linear part and the second linear part. The output shaft positions of the first motor and the second motor are controllable. 【0008】 This disclosure allows control of the position (rotation angle) of the output shafts of the first and second motors. Therefore, the distance between the first and second linear motion components can be adjusted, thereby changing the amount of elastic body contraction. Furthermore, by changing the amount of elastic body contraction, the axial load acting on the first linear motion component can be set to a desired magnitude. Thus, according to this disclosure, a motor for controlling the axial load (controlling torque) becomes unnecessary. Moreover, according to this disclosure, the distance between the first and second linear motion components (the amount of elastic body contraction) can be changed by driving the second motor, regardless of the axial position of the first linear motion component. Therefore, the axial load can be adjusted (changed) in accordance with the stroke of the ball screw device. 【0009】 Furthermore, in the ball screw device testing apparatus described above, the load device has a movable component that is movably arranged in the axial direction and contacts the first linear component from the second direction. The movable component may be biased in the first direction by the elastic body. 【0010】 Furthermore, in the ball screw device testing apparatus described above, the load device has a linear guide that supports the movable component so that it can move in the axial direction. 【0011】 According to the above configuration, the moving parts are less likely to rattle. 【0012】 Furthermore, in the ball screw device testing apparatus described above, the load device has an elastic body support portion that supports the elastic body. The elastic body support portion has a main body portion connected to the second linear motion component, and a rod that is movably supported by the main body portion and has a flange formed at its end in the first direction. The rod passes through the elastic body, and the main body portion and the flange may sandwich the elastic body from the axial direction. 【0013】 Furthermore, the ball screw device testing apparatus described above includes a control unit that controls the driving of the first motor and the second motor. The control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed. The control unit controls the driving of the second motor so that the second linear motion component moves at the same speed as the first linear motion component and in the same direction as the first linear motion component. 【0014】 According to the above configuration, the distance between the first linear motion component and the second linear motion component remains constant, and the amount of contraction of the elastic body also remains constant. Therefore, even if the stroke of the ball screw device increases or decreases, the axial load remains constant. 【0015】 Furthermore, the ball screw device testing apparatus described above includes a control unit that controls the driving of the first motor and the second motor. The control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed. The control unit controls the driving of the second motor so that the second linear motion component moves at a constant speed and at a smaller speed than the first linear motion component, in the same direction as the first linear motion component. 【0016】 According to the above configuration, when the first linear motion component moves in the second direction, the distance between the first and second linear motion components decreases. Furthermore, since the movement speeds of the first and second linear motion components are constant, the ratio between the amount of movement in the second direction by the first linear motion component and the amount of reduction in the distance between the first and second linear motion components (amount of elastic body contraction) remains constant. Therefore, as the amount of movement in the second direction by the first linear motion component increases, the axial load increases linearly. 【0017】 Furthermore, the ball screw device testing apparatus described above includes a control unit that controls the driving of the first motor and the second motor. The control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed. The control unit controls the driving of the second motor so that the second linear motion component moves in the opposite direction to the first linear motion component at a constant speed. 【0018】 According to the above configuration, when the first linear motion component moves in the second direction, the second linear motion component moves in the first direction, and the distance between the first and second linear motion components decreases. Furthermore, since the movement speeds of the first and second linear motion components are constant, the ratio between the amount of movement in the second direction by the first linear motion component and the amount of reduction in the distance between the first and second linear motion components (amount of elastic body contraction) remains constant. Therefore, as the amount of movement in the second direction by the first linear motion component increases, the axial load increases linearly. 【0019】 Furthermore, the ball screw device testing apparatus described above includes a control unit that controls the driving of the first motor and the second motor. The control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed. The control unit also controls the driving of the second motor so that the second linear motion component moves in the same direction as the first linear motion component at a lower speed than the first linear motion component. In addition, the second linear motion component decelerates as the amount of movement in the second direction increases. 【0020】 According to the above configuration, when the first linear motion component moves in the second direction, the distance between the first and second linear motion components decreases. However, the second linear motion component decelerates as the amount of movement in the second direction increases. Therefore, the ratio between the amount of movement in the second direction by the first linear motion component and the amount of reduction in the distance between the first and second linear motion components (amount of elastic contraction) is not constant. With this driving method, the axial load increases as the amount of movement in the second direction by the first linear motion component increases, but the axial load is kept low when the distance of movement of the first linear motion component in the second direction is small. 【0021】The test apparatus for ball screw devices described herein eliminates the need for expensive motors to achieve arbitrary torque control for controlling the axial load. Furthermore, an inexpensive motor can be used to adjust the axial load in accordance with the stroke of the ball screw device. 【0022】 Figure 1 is a schematic diagram of a test apparatus for a ball screw device according to an embodiment, viewed from the horizontal. Figure 2 is a graph showing the positions of the first linear motion component and the second linear motion component when the first drive method is implemented in the embodiment. Figure 3 is a graph showing the relationship between the stroke of the ball screw device and the axial load when the first drive method is implemented in the embodiment. Figure 4 is a graph showing the positions of the first linear motion component and the second linear motion component when the second, third, and fourth drive methods are implemented in the embodiment. Figure 5 is a graph showing the relationship between the stroke of the ball screw device and the axial load when the second, third, and fourth drive methods are implemented in the embodiment. Figure 6 is a graph showing the positions of the first linear motion component and the second linear motion component when the fifth drive method is implemented in the embodiment. Figure 7 is a graph showing the relationship between the stroke of the ball screw device and the axial load when the fifth drive method is implemented in the embodiment. Figure 8 is a schematic diagram of a modified test apparatus for a ball screw device, viewed from the horizontal. 【0023】 The forms for implementing this disclosure will be described in detail with reference to the drawings. This disclosure is not limited by the contents described below. Furthermore, the components described below include those that are readily conceivable to a person skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate. 【0024】 (Embodiment) Figure 1 is a schematic diagram of the test apparatus for a ball screw device according to the embodiment, viewed from the horizontal direction. Before describing the test apparatus 100 for a ball screw device according to the embodiment, the ball screw device 110 will be briefly described. The ball screw device 110 comprises a screw shaft 111, a nut 112 into which the screw shaft 111 is inserted, and a plurality of balls (not shown) arranged between the screw shaft 111 and the nut 112. Hereinafter, the direction parallel to the central axis O of the screw shaft 111 will be referred to as the axial direction. 【0025】 In the ball screw device 110, during testing of the ball screw device testing apparatus 100 (hereinafter simply referred to as "test"), torque is transmitted to one of the components, the screw shaft 111 and the nut 112, causing that component (the first rotating component) to rotate. The other component of the screw shaft 111 and nut 112 (the first linear component) then moves linearly in the axial direction (hereinafter sometimes referred to as linear motion). In this embodiment, the screw shaft 111 corresponds to the first rotating component, and the nut 112 corresponds to the first linear component. 【0026】 Next, the ball screw device testing apparatus 100 will be described. In the following description, the ball screw device 110 to be tested will be described as already attached to the ball screw device testing apparatus 100. 【0027】 As shown in Figure 1, the ball screw device test apparatus 100 of the embodiment includes a base 101, a support part 1 for supporting the ball screw device 110, an actuator 2 for operating the ball screw device 110, a load device 3 for applying an axial load to the ball screw device 110, and a control unit 4. 【0028】 In this embodiment, the base 101 extends horizontally. The installation surface 102 of the base 101 faces upward Y in the vertical direction. In this embodiment, the base 101 is horizontal, but in this disclosure, the base 101 may be inclined with respect to the horizontal direction, or the normal to the base 101 may extend horizontally, and the orientation of the base 101 is not particularly limited. 【0029】 The support part 1 rotatably supports the screw shaft 111. The support part 1 also supports the nut 112 so that it is immobile and movable in the axial direction. Furthermore, in the ball screw device 110 supported by the support part 1, the central axis O of the screw shaft 111 is horizontal. 【0030】 Viewed from the support unit 1, the actuator 2 is positioned in one axial direction, and the load device 3 is positioned in the other axial direction. Hereinafter, the direction in which the actuator 2 is positioned, as viewed from the support unit 1, will be referred to as the first direction X1, and the direction in which the load device 3 is positioned, as viewed from the support unit 1, will be referred to as the second direction X2. 【0031】The actuator 2 comprises a first motor 20 and a torque sensor 23 arranged in order from a first direction X1. The first motor 20 generates torque to operate the ball screw device 110. The first motor 20 is a servo motor comprising a motor body 21, an output shaft 22 extending from the motor body 21 in a second direction X2, an encoder (not shown) for detecting the position (rotation angle) of the output shaft 22, and an amplifier (not shown) for controlling the rotation angle of the output shaft 22 to an angle specified by the control unit 4. 【0032】 The torque sensor 23 is positioned between the support unit 1 (ball screw device 110) and the first motor 20, and measures the torque transmitted to the ball screw device 110. The torque sensor 23 has a sensor body 24, a first shaft 25 extending from the sensor body 24 in a first direction X1, and a second shaft 26 extending from the sensor body 24 in a second direction X2. The output shaft 22 and the first shaft 25 are connected by a coupling 90. The second shaft 26 and the screw shaft 111 are connected by a coupling 91. 【0033】 According to the actuator 2 described above, when the first motor 20 is driven, torque is transmitted to the screw shaft 111 via the torque sensor 23. As a result, the screw shaft 111 rotates, and the nut 112 moves in the axial direction. 【0034】 The load device 3 comprises a second motor 30 arranged in order from the second direction X2, a load-side ball screw device 33, an elastic body support 37, an elastic body 45, a load cell 47, and a movable part 50. 【0035】 The second motor 30 generates torque to operate the load-side ball screw device 33. The second motor 30 is a servo motor comprising a motor body 31, an output shaft 32 extending from the motor body 31 in a first direction X1, an encoder (not shown) for detecting the position (rotation angle) of the output shaft 32, and an amplifier (not shown) for controlling the rotation angle of the output shaft 32 to an angle specified by the control unit 4. 【0036】The load-side ball screw device 33 converts the rotational motion generated by the second motor 30 into linear motion. The load-side ball screw device 33 comprises a screw shaft 34, a nut 35, and a plurality of balls (not shown). In the load device 3, torque is transmitted to one of the components of the screw shaft 34 and the nut 35, causing that component (the second rotating component) to rotate. The other component of the screw shaft 34 and the nut 35 (the second linear component) then moves linearly in the axial direction. In the ball screw device test apparatus 100 of this embodiment, the screw shaft 34 corresponds to the second rotating component, and the nut 35 corresponds to the second linear component. 【0037】 The base 101 is provided with a load-side support portion 36 that supports the load-side ball screw device 33. The load-side support portion 36 rotatably supports the screw shaft 34. The load-side support portion 36 also supports the nut 35 so that it cannot be rotated but can move in the axial direction. The screw shaft 34 is connected to the output shaft 32 of the second motor 30 by a coupling 92. 【0038】 The elastic support portion 37 comprises a main body portion 38 and a rod 39 extending from the main body portion 38 in a first direction X1. The rod 39 is supported by the main body portion 38 so as to be movable in the axial direction. Therefore, the elastic support portion 37 is expandable and contractible in the axial direction. A flange 40 is provided at the end of the rod 39 in the first direction X1. 【0039】 The elastic body 45 is a component that exerts a biasing force. The elastic body 45 is positioned between the end face of the main body 38 in a first direction X1 and the flange 40, biasing the flange 40 in the first direction X1. Specific examples of the elastic body 45 include coil springs and disc springs. In addition, in this disclosure, if disc springs are used, multiple disc springs may be arranged in the axial direction. 【0040】 In this embodiment, the main body 38 is supported so as to be movable in the axial direction by a linear guide 41 fixed to the base 101. The linear guide 41 has a rail 42 that extends in the axial direction and a slider 43 that is movable in the axial direction along the rail 42. A nut 35 (second linear motion component) of the load-side ball screw device 33 is connected to the end of the main body 38 in the second direction X2. 【0041】The load cell 47 measures the axial load. The load cell 47 is connected to the flange 40 of the elastic body support portion 37 in the first direction X1. 【0042】 The moving part 50 is connected in the first direction X1 of the load cell 47. In the first direction X1 of the moving part 50, the nut 112 of the ball screw device 110 is arranged. The end portion of the moving part 50 in the first direction X1 abuts on the surface of the nut 112 in the second direction X2. Further, a fitting portion 56 recessed in the second direction X2 is formed in the end face 55. The end portion of the nut 112 in the second direction X2 is fitted in the fitting portion 56. 【0043】 The moving part 50 is supported by a linear guide 51 fixed to the base 101 so as to be axially movable. The linear guide 51 has a rail 52 extending in the axial direction and a slider 53 axially movable along the rail 52. Further, preload is applied to the linear guide 51 of the present embodiment, and the moving part 50 is less likely to have play. 【0044】 According to the load device 3 described above, when the distance between the nut 112 (first linear moving part) and the nut 35 (second linear moving part) becomes small, the axial length L1 (see FIG. 1) of the elastic body 45 becomes small. Further, when the axial length L1 of the elastic body 45 becomes smaller than the natural length of the elastic body 45, the elastic body 45 accumulates elastic energy. Thereby, the elastic body 45 biases the moving part 50 in the first direction X1. Then, the moving part 50 presses the nut 112 in the first direction X1 (see arrow A in FIG. 1). In this way, a load (axial load) in the first direction X1 acts on the nut 112. 【0045】 The control unit 4 is a device for controlling the driving of the first motor 20 and the second motor 30. The control unit 4 controls the operation of the ball screw device 110 through the control of the first motor 20. That is, the control unit 4 controls the position (rotation angle) of the output shaft 22 of the first motor 20 so that the ball screw device 110 performs an operation corresponding to the test content. 【0046】In addition, the control unit 4 controls the axial position of the nut 35 (the distance from the nut 35 to the nut 112) via the drive of the second motor 30. Here, when the distance between the nut 35 and the nut 112 increases, the contraction amount of the elastic body 45 decreases, and the axial load decreases. On the other hand, when the distance between the nut 35 and the nut 112 decreases, the contraction amount of the elastic body 45 increases, and the axial load increases. Thus, the magnitude of the axial load is determined by the distance between the nut 112 and the nut 35. From the above, the control unit 4 controls the position (rotation angle) of the output shaft 32 of the second motor 30 so that the axial load becomes a predetermined magnitude. 【0047】 Next, the driving methods of the first motor 20 and the second motor 30 during the test will be described. In the present embodiment, one example of the driving method of the first motor 20 is shown. On the other hand, there are five types of driving methods for the second motor 30 (the first driving method, the second driving method, the third driving method, the fourth driving method, and the fifth driving method). Each driving method will be described below. 【0048】 (Driving method of the first motor) FIG. 2 is a graph showing the positions of the first linear motion part and the second linear motion part when the first driving method is implemented in the embodiment. The driving method of the first motor 20 repeatedly performs an operation of rotating the output shaft 22 of the first motor 20 forward and then backward. As a result, as shown in FIG. 2, the nut 112 (the first linear motion part) of the ball screw device 110 moves in the second direction X2 from the initial position, then moves in the first direction X1, and repeats the operation of returning to the initial position. Also, the moving speed of the nut 112 is made constant. Furthermore, this driving method of the first motor 20 is uniformly performed in each driving method of the second motor 30. 【0049】 (First driving method of the second motor) The first driving method of the second motor 30 is to drive the second motor 30 before the start of the test to make the length L1 of the elastic body 45 smaller than the natural length. As a result, the elastic body 45 contracts, and a predetermined amount of axial load is applied to the nut 112 from the start of the test. 【0050】Once the test begins, the output shaft 32 of the second motor 30 is repeatedly rotated forward and then in the reverse direction. In other words, the nut 35 (second linear motion component) moves in the same direction as the nut 112 of the ball screw device 110. The speed at which the nut 35 moves is also set to be the same as that of the nut 112. With this first driving method, the distance between the nut 112 and the nut 35 remains constant. In other words, the amount of contraction of the elastic body 45 remains constant, and the axial load also remains constant. 【0051】 Figure 3 is a graph showing the relationship between the stroke of the ball screw device and the axial load when the first driving method is implemented in the embodiment. The stroke on the horizontal axis of Figure 3 represents the amount of movement of the nut 112 (first linear motion component) from its initial position to the second direction X2. As shown in Figure 3, with the first driving method, even if the stroke of the ball screw device 110 changes (even if the axial position of the nut 112 changes), the axial load on the nut 112 remains constant. 【0052】 Next, the second to fourth driving methods will be explained. In these methods, the second motor 30 is not driven before the start of the test. In other words, the length L1 of the elastic body 45 is the natural length of the elastic body 45, and no axial load is applied to the ball screw device 110 at the start of the test. 【0053】 (Second driving method for the second motor) Figure 4 is a graph showing the positions of the first linear motion component and the second linear motion component when the second driving method, the third driving method, and the fourth driving method are implemented in the embodiment. Figure 5 is a graph showing the relationship between the stroke of the ball screw device and the axial load when the second driving method, the third driving method, and the fourth driving method are implemented in the embodiment. 【0054】 As shown in Figure 4, the second drive method does not drive the second motor 30 even when the test starts. In other words, the nut 35 (second linear motion component) does not move in the axial direction. Therefore, when the nut 112 (first linear motion component) moves in the second direction X2, the distance between the nut 35 and the nut 112 decreases. 【0055】Furthermore, in the second driving method, the nut 35 stops, and the movement speed of the nut 112 remains unchanged. Therefore, the ratio between the amount of movement of the nut 112 in the second direction X2 and the amount of reduction in the distance between the nut 112 and the nut 35 is constant. In other words, the amount of movement of the nut 112 in the second direction X2 and the amount of contraction of the elastic body 45 are proportional. 【0056】 As described above, according to the second driving method, as shown in Figure 5, the axial load increases in proportion to the increase in the stroke of the ball screw device 110. 【0057】 (Third driving method for the second motor) As shown in Figure 4, the third driving method involves repeatedly rotating the output shaft 32 of the second motor 30 in the forward and reverse directions once the test has started, moving the nut 35 (second linear motion component) in the same direction as the nut 112 (first linear motion component). The speed at which the nut 35 moves is kept constant. However, the speed at which the nut 35 moves is made smaller than that of the nut 112. With this third driving method, when the nut 112 moves in the second direction X2, the distance between the nut 112 and the nut 35 decreases. 【0058】 Furthermore, in the third driving method, the speeds of the nuts 112 and 35 remain constant. Therefore, the ratio between the amount of movement of the nut 112 in the second direction X2 and the amount of reduction in the distance between the nuts 112 and 35 is constant. In other words, the amount of movement of the nut 112 in the second direction X2 and the amount of contraction of the elastic body 45 are proportional. 【0059】 From the above, according to the third driving method, as shown in Figure 5, the axial load increases in proportion to the increase in the stroke of the ball screw device 110. 【0060】 (Fourth driving method for the second motor) In the fourth driving method, once the test has started, the output shaft 32 of the second motor 30 is repeatedly rotated forward and in the reverse direction, while the nut 35 (second linear motion component) is moved in the opposite direction to the nut 112 (first linear motion component). The speed at which the nut 35 moves is kept constant. Also, the speed at which the nut 35 moves is smaller than that of the nut 112. With this fourth driving method, when the nut 112 moves in the second direction X2, the distance between the nut 112 and the nut 35 (second linear motion component) decreases. 【0061】 Furthermore, in the fourth driving method, the speeds of the nuts 112 and 35 remain constant. Therefore, the ratio between the amount of movement of the nut 112 in the second direction X2 and the amount of reduction in the distance between the nuts 112 and 35 is constant. In other words, the amount of movement of the nut 112 in the second direction X2 and the amount of contraction of the elastic body 45 are proportional. 【0062】 From the above, according to the fourth driving method, as shown in Figure 5, the axial load increases in proportion to the increase in the stroke of the ball screw device 110. 【0063】 As described above, with the second, third, and fourth driving methods, as the amount of movement of the nut 112 (first linear motion component) in the second direction X2 increases, the axial load increases linearly (linearly). 【0064】 Furthermore, according to the third driving method, when the nut 112 moves in the second direction X2, the nut 35 also moves in the same direction (second direction X2). Therefore, even if the amount of movement (stroke) of the nut 112 is the same, the amount of contraction of the elastic body 45 is smaller. In other words, the axial load is smaller than in the second driving method (see Figure 5 when the stroke is S). 【0065】 Furthermore, in the fourth driving method, when the nut 112 moves in the second direction X2, the nut 35 moves in the opposite direction (first direction X1). Therefore, even if the amount of movement (stroke) of the nut 112 is the same, the amount of contraction of the elastic body 45 is larger. In other words, the axial load is larger than in the second driving method (see Figure 5 when the stroke is S). 【0066】 (Fifth driving method for the second motor) Figure 6 is a graph showing the positions of the first linear motion component and the second linear motion component when the fifth driving method is implemented in the embodiment. Figure 7 is a graph showing the relationship between the stroke of the ball screw device and the axial load when the fifth driving method is implemented in the embodiment. 【0067】In the fifth driving method, the second motor 30 is not driven before the start of the test. In other words, the length L1 of the elastic body 45 is the natural length of the elastic body 45, and no axial load is applied to the ball screw device 110 at the start of the test. 【0068】 As shown in Figure 6, the fifth driving method, once the test has started, repeatedly rotates the output shaft 32 of the second motor 30 in the forward and reverse directions, causing the nut 35 (second linear motion component) to move in the same direction as the nut 112 (first linear motion component). The speed at which the nut 35 moves is smaller than that of the nut 112. With this fifth driving method, when the nut 112 moves in the second direction X2, the distance between the nut 112 and the nut 35 decreases. 【0069】 Furthermore, in the fifth driving method, as the amount of movement of the nut 35 in the second direction X2 increases, the nut 35 decelerates. For this reason, the ratio between the amount of movement of the nut 112 in the second direction X2 and the amount of reduction in the distance between the nut 112 and the nut 35 is not constant. In other words, the amount of contraction of the elastic body 45 is not proportional to the amount of movement of the nut 112 in the second direction X2. 【0070】 As described above, with the fifth driving method, the axial load increases exponentially as the stroke of the ball screw device 110 increases. With this fifth driving method, the axial load can be kept relatively small when the amount of movement of the nut 112 (first linear motion component) in the second direction X2 is small. 【0071】 The various drive methods have been described above. The ball screw device test apparatus 100 of the above embodiment adjusts the magnitude of the axial load using a first motor 20 and a second motor 30 that can control the position (rotation angle) of the output shafts 22 and 32. Therefore, expensive motors for achieving arbitrary torque control are not required, and production costs can be reduced. In addition, by controlling the drive of the second motor 30, it is possible to adjust the axial load in accordance with the stroke of the ball screw device 110. 【0072】Although embodiments have been described above, this disclosure is not limited to the examples described above. For example, the ball screw device testing apparatus 100 of this disclosure may further include a reduction gear to increase the torque of the first motor 20 and the second motor 30. Also, if the test is not for testing efficiency but for confirming operation, such as whether abnormal noise occurs, or for evaluating durability, the ball screw device testing apparatus 100 does not need to be equipped with a torque sensor 23 or a load cell 47. Furthermore, a temperature sensor or the like may be added to the ball screw device testing apparatus 100 to measure the temperature of the ball screw device 110 during testing. 【0073】 Furthermore, in this embodiment, the screw shaft 111 of the ball screw device 110 constitutes a first rotating component and the nut 112 constitutes a first linear component. However, in this disclosure, the screw shaft 111 may constitute a first linear component and the nut 112 may constitute a first rotating component. Similarly, with respect to the load-side ball screw device 33, in this disclosure, the nut 35 may constitute a second rotating component and the screw shaft 34 may constitute a second linear component. 【0074】 Furthermore, although a fitting portion 56 is formed on the end face 55 of the movable part 50 in the embodiment, the present disclosure indicates that the fitting portion 56 may not be formed on the end face 55. In other words, the end face 55 may be formed as a flat surface and simply come into contact with the nut 112 (first linear motion part) from the second direction X2. 【0075】 Furthermore, although the embodiment has an elastic support portion 37, the present disclosure does not require the elastic support portion 37. In other words, the elastic body 45 may be placed between the nut 35 (second linear motion component) and the moving component 50, so that both ends of the elastic body 45 are in contact with the nut 35 (second linear motion component). Also, although the embodiment applies an axial load to the first rotating component (nut 112) via the moving component 50, the present disclosure does not have a moving component 50, and the elastic body 45 may be in contact with the first rotating component (nut 112). 【0076】Figure 8 is a schematic diagram of a modified ball screw device test apparatus viewed from the horizontal. The present disclosure may also be the modified ball screw device test apparatus 100A shown in Figure 8. The modified ball screw device test apparatus 100A does not have an elastic body support part 37 and a movable part 50. Therefore, the end of the elastic body 45 in the first direction X1 is in contact with the nut 112 (first linear motion part). The end of the elastic body 45 in the second direction X2 is in contact with the nut 35 (second linear motion part). The method of fixing the elastic body 45 to the nut 35 (second linear motion part) is not particularly limited. Even with this modified form, the cost of the ball screw device test apparatus 100A can be reduced, similar to the embodiment. Furthermore, by controlling the drive of the second motor 30, the axial load can be adjusted in accordance with the stroke of the ball screw device 110. 【0077】 Furthermore, regarding the fifth driving method, in the embodiment, the moving speed of the nut 35 (second linear motion component) gradually decreases as the amount of movement in the second direction X2 increases, but the present disclosure does not require such a moving speed (deceleration). For example, the nut 35 may move while maintaining a constant first speed for a predetermined distance from the test start position, and then move while maintaining a second speed smaller than the first speed. In other words, the nut 35 may move at a relatively high moving speed at the start of the test, and then move at a relatively low moving speed thereafter. In this driving method, the moving speed of the nut 35 is in two stages, and similar to the fifth driving method in the embodiment, the axial load can be made relatively small when the amount of movement of the nut 112 (first linear motion component) in the second direction X2 is small. Thus, in the fifth driving method of the present disclosure, the nut 35 (second linear motion component) only needs to decelerate when the amount of movement in the second direction X2 increases, and there are no particular restrictions in the deceleration process. 【0078】 Furthermore, regarding the second to fifth driving methods of the second motor 30, in Embodiment 1, no axial load is applied to the nut 112 at the start of the test. However, in this disclosure, the elastic body 45 may be contracted before the start of the test, and the test may be started with an axial load applied to the nut 112. 【0079】Furthermore, the driving method for the first motor 20 in the embodiment is illustrative, and other driving methods may be used. Also, in the fourth driving method of the embodiment, the moving speed of the nut 35 (second linear motion component) is smaller than that of the nut 112 (first linear motion component), but in this disclosure, it is sufficient that the nut 35 moves in the opposite direction to the nut 112, and there are no particular restrictions on the moving speed of the nut 35. In other words, it may be larger than or the same as that of the nut 112. 【0080】 1 Support part 2 Actuator 3 Load device 4 Control unit 20 First motor 21 Motor body 22, 32 Output shaft 23 Torque sensor 24 Sensor body 25 First shaft 26 Second shaft 30 Second motor 31 Motor body 33 Load-side ball screw device 34 Screw shaft (second rotating part) 35 Nut (second linear motion part) 36 Load-side support part 37 Elastic support part 38 Main body 39 Rod 40 Flange 41, 51 Linear guide 42, 52 Rail 43, 53 Slider 45 Elastic body 47 Load cell 50 Moving part 55 End face 56 Fitting part 100, 100A Test device for ball screw device 101 Base 102 Installation surface 110 Ball screw device 111 Screw shaft (first rotating part) 112 Nut (first linear motion part)
Claims
1. A test device for a ball screw device comprising: a support portion that rotatably supports one of the first rotating parts of a ball screw device to be tested, a screw shaft and a nut, and linearly supports the other first linear part; a first motor that is positioned in a first direction which is one of the axial directions parallel to the central axis of the screw shaft as viewed from the support portion, and generates torque to rotate the first rotating part; and a load device that is positioned in a second direction which is the other of the axial directions as viewed from the support portion, and contacts the first linear part to apply an axial load to the first linear part, wherein the load device comprises: a second motor; a load-side ball screw device having a second rotating part that rotates by the torque generated by the second motor and a second linear part that moves linearly by the rotation of the second rotating part; and an elastic body interposed between the first linear part and the second linear part, wherein the position of the output shafts of the first motor and the second motor are controllable.
2. The test apparatus for a ball screw device according to claim 1, wherein the load device is arranged to be movable in the axial direction and has a movable part that contacts the first linear part from the second direction, and the movable part is biased in the first direction by the elastic body.
3. The test apparatus for a ball screw device according to claim 2, wherein the load device has a linear guide that supports the movable component so as to be movable in the axial direction.
4. The test apparatus for a ball screw device according to claim 3, wherein the load device has an elastic body support portion that supports the elastic body, the elastic body support portion has a main body portion connected to the second linear motion component, and a rod that is movably supported by the main body portion and has a flange formed at its end in the first direction, the rod passes through the elastic body, and the main body portion and the flange sandwich the elastic body from the axial direction.
5. A test apparatus for a ball screw device according to any one of claims 1 to 4, comprising a control unit for controlling the driving of the first motor and the second motor, wherein the control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed, and controls the driving of the second motor so that the second linear motion component moves in the same direction as the first linear motion component at the same speed as the first linear motion component.
6. A test apparatus for a ball screw device according to any one of claims 1 to 4, comprising a control unit for controlling the driving of the first motor and the second motor, wherein the control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed, and controls the driving of the second motor so that the second linear motion component moves at a constant speed and at a smaller speed than the first linear motion component in the same direction as the first linear motion component.
7. A test apparatus for a ball screw device according to any one of claims 1 to 4, comprising a control unit for controlling the driving of the first motor and the second motor, wherein the control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed, and controls the driving of the second motor so that the second linear motion component moves in the opposite direction to the first linear motion component at a constant speed.
8. A test apparatus for a ball screw device according to any one of claims 1 to 4, comprising a control unit for controlling the driving of the first motor and the second motor, wherein the control unit controls the driving of the first motor so that the first linear motion component moves in the axial direction at a constant speed, controls the driving of the second motor so that the second linear motion component moves in the same direction as the first linear motion component at a lower speed than the first linear motion component, and further decelerates when the amount of movement of the second linear motion component in the second direction increases.