Thrust maintaining device and control method thereof

Abstract

The invention relates to a thrust maintaining device and a control method thereof, which are both applied to a CNC (Computer Numerical Control) lathe, and the thrust maintaining device comprises a screw rod arranged in the CNC lathe, a jacking piece screwed on the screw rod, a motor connected with the screw rod, and a controller electrically connected with the motor, the controller stores a plurality of load values of the motor and a plurality of thrust values of the jacking piece on the workpiece, takes one of the plurality of load values as a working load value of the motor and calculates an instant load value when the motor operates; and whether the instant load value is equal to the working load value or not is used as a judgment basis for controlling the jacking piece to move, so that the jacking piece maintains the thrust value corresponding to the working load value to jack the workpiece, and the workpiece can be fixed in the CNC lathe in the machining process so as to stabilize the whole machining process.

Description

Technical Field

[0001] The present invention relates to a numerical control machine tool, and in particular to a thrust maintaining device and a control method thereof applied to the numerical control machine tool. Background Art

[0002] Machine tools are a crucial piece of equipment in the manufacturing process of mechanical parts. With the development of the automation industry, machine tools, which used to require manual operation, have gradually evolved into computer numerical control (CNC) machines to meet market demand. CNC machine tools can be categorized by machining method, including CNC lathes, CNC milling machines, CNC grinders, and CNC drilling machines. For example, a CNC lathe typically clamps a workpiece to be machined. A pin holds the workpiece in place from the opposite side of the clamp. A turning tool is then placed against the workpiece's surface, and the workpiece is rotated to perform machining.

[0003] Among them, the ejector pin in the existing CNC lathe is installed on a hydraulic slide. The hydraulic slide is then moved by computer numerical control to move the ejector pin between a holding position and a standby position. The holding position is the position of the ejector pin when the workpiece is being processed. This means that the ejector pin is fixed at this holding position during the processing of the workpiece. However, during the processing of the workpiece, the workpiece may deviate slightly due to rotation. The ejector pin cannot move accordingly, resulting in insufficient force to hold the workpiece. When the workpiece is processed without being completely fixed, the quality of the finished workpiece will be questionable. The workpiece may even be ejected due to continued deviation, damaging other mechanical structures in the CNC lathe. Summary of the Invention

[0004] When a conventional CNC lathe is processing a workpiece, it is unable to continuously support the workpiece with a constant force, resulting in concerns about the quality of the workpiece after processing. In view of this, the present invention provides a thrust holding device and a control method thereof to overcome the aforementioned problem.

[0005] The thrust maintaining device of the present invention is applied to a CNC lathe, and the device comprises:

[0006] a screw disposed in the CNC lathe;

[0007] a supporting member, threadedly mounted on the screw rod, for supporting a workpiece;

[0008] a motor connected to and driving the screw to rotate;

[0009] a controller electrically connected to the motor, the controller receiving a power signal from the motor and calculating a real-time load value of the motor when the motor is running according to the power signal, and the controller storing a plurality of load values ​​of the motor and a plurality of thrust values ​​of the supporting member on the workpiece, the plurality of load values ​​corresponding to the plurality of thrust values, and the plurality of load values ​​being different from each other, and the plurality of thrust values ​​being different from each other;

[0010] The controller uses one of the multiple load values ​​as a working load value of the motor, and continuously determines whether the instantaneous load value when the motor is running is equal to the working load value. When the instantaneous load value when the motor is running is not equal to the working load value, the controller controls the supporting member to move so that the instantaneous load value when the motor is running is equal to the working load value, so that the supporting member maintains the thrust value corresponding to the working load value to support the workpiece.

[0011] A control method for a thrust maintaining device according to the present invention is applied to a thrust maintaining device disposed in a CNC lathe and comprising a screw, a supporting member, a motor, and a controller, wherein the supporting member is threadedly mounted on the screw, the screw is connected to the motor, and the motor is electrically connected to the controller. The control method is executed by the controller and comprises:

[0012] storing a plurality of load values ​​of the motor and a plurality of thrust values ​​of the supporting member on a workpiece;

[0013] Establishing a relationship between the plurality of load values ​​and the plurality of thrust values, wherein the plurality of load values ​​correspond to the plurality of thrust values ​​respectively, and the plurality of load values ​​are different from each other, and the plurality of thrust values ​​are different from each other;

[0014] Setting one of the plurality of load values ​​as a working load value of the motor;

[0015] receiving a power signal from the motor;

[0016] Calculating a real-time load value of the motor when it is running according to the power signal;

[0017] Continuously determining whether the instantaneous load value of the motor when it is running is equal to the working load value;

[0018] When the instantaneous load value when the motor is running is not equal to the working load value, the controller controls the supporting member to move so that the instantaneous load value when the motor is running is equal to the working load value, so that the supporting member maintains the thrust value corresponding to the working load value to support the workpiece.

[0019] The thrust maintaining device and control method of the present invention have the following common features: both are applied to a CNC lathe; both the thrust maintaining device and control method store multiple load values ​​of the motor and multiple thrust values ​​of the supporting member on the workpiece through the controller; wherein the CNC lathe is provided with the screw, the supporting member is provided on the screw, and the screw is connected to the motor, and the motor is electrically connected to the controller; the multiple load values ​​in the controller correspond to the multiple thrust values, and the multiple load values ​​are different from each other, and the multiple thrust values ​​are different from each other, and the controller uses one of the multiple load values ​​to store the multiple thrust values. One is used as the working load value of the motor and the real-time load value of the motor is calculated according to the power signal of the motor, and the controller continuously determines whether the real-time load value of the motor is equal to the working load value. When the real-time load value of the motor is not equal to the working load value, the controller controls the movement of the supporting member so that the real-time load value of the motor when running is equal to the working load value. The supporting member maintains the thrust value corresponding to the working load value to support the workpiece, thereby allowing the workpiece to be fixed in the CNC lathe during processing and stabilize the entire processing process, thereby improving the production yield of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 : Schematic diagram of the structure of the thrust maintaining device of the present invention arranged on a CNC lathe, wherein the supporting member supports the workpiece.

[0021] Figure 2 :Circuit block diagram of the thrust maintaining device of the present invention.

[0022] Figure 3 : Schematic diagram of the structure of the thrust maintaining device of the present invention arranged on a CNC lathe, wherein the top holding member holds the load cell.

[0023] Figure 4 : Schematic diagram of the relationship curve between the load value of the motor in the thrust maintaining device of the present invention and the thrust value of the supporting member on the workpiece.

[0024] Figure 5 : Flow chart of the steps of the control method of the thrust holding device of the present invention. DETAILED DESCRIPTION

[0025] In order to understand the technical features and practical effects of the present invention in detail and to realize the invention according to the present invention, the embodiments shown in the figures are further described in detail as follows:

[0026] See also Figure 1 and Figure 2The thrust maintaining device of the present invention is provided for a CNC lathe 1, and the thrust maintaining device includes a screw 10, a supporting member 20, a motor 30 and a controller 40. The CNC lathe 1 has a housing 50, and a processing space is provided inside the housing 50. A clamping mechanism 51 is provided in the processing space, and the clamping mechanism 51 is used to clamp a workpiece W to be processed. For example, the workpiece W is a metal cylinder. The clamping mechanism 51 can clamp the metal cylinder so that the metal cylinder lies horizontally in the processing space. Because the clamping mechanism 51 is not the technical focus of the present invention, it is not described in detail here.

[0027] The screw 10 is set in the CNC lathe, and the supporting member 20 is screwed on the screw 10. The supporting member 20 is used to support the workpiece W. Specifically, the screw 10 is set in the housing 50. The screw 10 is controlled to rotate to drive the supporting member 20 to move linearly back and forth on the screw 10, and the supporting member 20 corresponds to the position of the clamping mechanism 51. When the clamping mechanism 51 clamps the workpiece W, the supporting member 20 can support the workpiece W by linear movement, thereby achieving the effect of fixing the workpiece W.

[0028] In one embodiment of the present invention, the screw 10 is a ball screw, and the supporting member 20 includes a tail stock 21 and a thimble 22. The tail stock 21 is screwed onto the screw 10, and the thimble 22 is disposed on the tail stock 21. For example, as described above, the workpiece W lies horizontally in the processing space, and the screw 10 is correspondingly disposed horizontally in the housing 50. The screw 10 rotates to drive the tail stock 21 to move, so that the tail stock 21 and the thimble 22 can move linearly on the screw 10, that is, the tail stock 21 and the thimble 22 reciprocate horizontally and linearly in the processing space, and then the workpiece W is supported and fixed by the thimble 22.

[0029] The motor 30 is connected to and drives the screw 10 to rotate, so as to drive the supporting member 20 to move on the screw 10. For example, the transmission shaft of the motor 30 is connected to the screw 10 through a transmission mechanism, and the transmission mechanism includes, for example, a reducer, a coupling, etc. How a motor is connected to a screw is common knowledge in the art and will not be described in detail here. In one embodiment of the present invention, the motor 30 is a servo motor, and the transmission shaft of the motor 30 can be controlled to rotate forward or reverse, so that The screw rod 10 connected thereto rotates forward or reversely, causing the supporting member 20 on the screw rod 10 to advance or retreat. The forward rotation of the drive shaft of the motor 30 may cause the supporting member 20 to advance or retreat. When the forward rotation of the drive shaft of the motor 30 causes the supporting member 20 to advance, the reverse rotation of the drive shaft of the motor 30 causes the supporting member 20 to retreat. Alternatively, when the forward rotation of the drive shaft of the motor 30 causes the supporting member 20 to retreat, the reverse rotation of the drive shaft of the motor 30 causes the supporting member 20 to advance. The present invention is not limited to this.

[0030] The controller 40 is electrically connected to the motor 30, and the controller 40 receives an electric power signal from the motor 30 and calculates a real-time load value of the motor 30 when it is running based on the electric power signal, which means that the controller 40 can monitor the operation of the motor 30. For example, the controller 40 can control a power supply to provide different amounts of working power to the motor 30, and the motor 30 will transmit a feedback power signal to the controller 40, so that the controller 40 can calculate the operation-related values ​​of the motor 30 (such as the real-time load value) based on the feedback power signal to monitor the operation of the motor 30, wherein the feedback power signal is the power signal, and the power signal can be, for example, a current signal or a voltage signal of the motor 30.

[0031] The controller 40 also stores multiple load values ​​of the motor 30 and multiple thrust values ​​of the supporting member 20 on the workpiece W. The multiple load values ​​correspond to the multiple thrust values, and the multiple load values ​​are different from each other. The multiple thrust values ​​are different from each other. The controller 40 can be, for example, a computer numerical controller (CNC controller). How the controller 40 stores the multiple load values ​​and the multiple thrust values ​​can be set in a parameter adjustment and setting stage after the thrust maintaining device is installed on a CNC lathe. The parameter adjustment and setting process is described as follows.

[0032] like Figure 3As shown, the user can clamp a load cell 52 through the clamping mechanism 51. The load cell 52 is connected to a display 53. The load cell 52 is used to sense a thrust value generated by the supporting member 20. The display 53 is used to display the thrust value. The controller 40 is electrically connected to a human-machine interface 60. The user can operate the human-machine interface 60 to control the controller 40 to move the supporting member 20. For example, when the motor 30 is not running, the supporting member 20 is located at an origin position and is separated from the load cell 52. The controller 40 controls the motor 30 with a load value of 10% according to the user's operation, driving the supporting member 20 to move to a supporting position against the load cell 52. The supporting position is also defined as the position where the supporting member 20 is against a workpiece W.

[0033] Then, because the supporting member 20 is blocked by the load cell 52 (i.e., the supporting member 20 begins to support the load cell 52), the motor 30 will be stalled. If the user continues to operate the human-machine interface 60 and controls the controller 40 to allow the motor 30 to receive a larger current, the load value of the motor 30 will increase accordingly and be displayed on the human-machine interface 60. The user can thereby view and record multiple load values ​​of the motor 30 through the human-machine interface 60, and view and record multiple thrust values ​​of the supporting member 20 through the display 53. For example, when the load value of the motor 30 is 30%, the thrust value of the supporting member 20 on the load cell 52 is 250 kg. When the load value of the motor 30 is 40%, the thrust value of the supporting member 20 on the load cell 52 is 350 kg. After repeated measurement and recording, the user will obtain the multiple load values ​​and the multiple thrust values ​​of the supporting member 20 at the supporting position.

[0034] Subsequently, the human-machine interface 60 inputs the multiple load values ​​and the multiple thrust values ​​into the controller 40 according to the user's operation, and the controller 40 stores the multiple load values ​​and the multiple thrust values. In this way, the controller 40 stores the basis for controlling the motor 30 during the subsequent processing of the workpiece W. The relationship between the multiple load values ​​and the multiple thrust values ​​can be stored in the controller 40 in a data format such as a data table or a curve. Figure 4 Taking a characteristic curve C as an example, the characteristic curve C includes the multiple load values ​​and the multiple thrust values, and the multiple load values ​​correspond to the multiple thrust values ​​respectively. The multiple load values ​​are different from each other, and the multiple thrust values ​​are different from each other.

[0035] It should be noted that, since different workpieces may have different lengths, the supporting member 20 will be supported at multiple different positions (multiple different supporting positions). Therefore, the user can adjust the parameters through the load cells 52 of different lengths, and then establish multiple different supporting positions in the controller 40 to correspond to workpieces of different lengths. For example, the controller 40 stores a different first supporting position and a second supporting position. The first supporting position is used for a first workpiece processing process, and the second supporting position is used for a second workpiece processing process.

[0036] Please refer again Figure 1 and Figure 2 When the CNC lathe 1 processes (turns) the workpiece W, the controller 40 uses one of the multiple load values ​​as a working load value of the motor 30, and the controller 40 continuously determines whether the instantaneous load value when the motor 30 is running is equal to the working load value. When the instantaneous load value when the motor 30 is running is not equal to the working load value, the controller 40 controls the support member 20 to move so that the instantaneous load value when the motor 30 is running is equal to the working load value, so that the support member 20 maintains the thrust value corresponding to the working load value to support the workpiece W. Specifically, as described above, the controller 40 is electrically connected to the human-machine interface 60, and the human-machine interface 60 can be used for the user to output a thrust setting value. The controller 40 receives the thrust setting value, and the controller 40 finds one of the multiple thrust values ​​according to the thrust setting value. The load value corresponding to the thrust value is the working load value of the motor.

[0037] In order to facilitate understanding of the actual situation of the supporting member 20, the motor 30 and the processing process of the workpiece W, the thrust setting value of 250Kg is used as an example for explanation below. As mentioned above, the thrust setting value (250Kg) corresponds to the load value of 30% in the controller 40, that is, the working load value of the motor 30 is 30%.

[0038] First, before the supporting member 20 moves to the position against the workpiece W, the controller 40 controls the motor 30 to move the supporting member 20 with a basic load value, so that the supporting member 20 moves to the position against the workpiece W (the supporting position), wherein the basic load value refers to the minimum load value that the motor 30 can drive the supporting member 20 to move. The basic load value will vary according to factors such as different screw leads and different motor models, and is not limited to this. For the convenience of subsequent description, the basic load value can be, for example, 10%.

[0039] When the supporting member 20 reaches the supporting position, the controller 40 controls the motor 30 to receive a larger current (i.e., increases the instantaneous load value of the motor 30). The instantaneous load value of the motor 30 during operation will increase from 10% to 30% (the working load value). When the workpiece W deviates during machining and does not abut the supporting member 20, the instantaneous load value of the motor 30 will decrease. The controller 40 controls the supporting member 20 to move (advance toward the clamping mechanism 51) to support the workpiece W again. The motor 30 will stall again, causing the instantaneous load value to increase again to the working load value (30%). Conversely, when the thrust of the supporting member 20 on the workpiece W during machining exceeds the user-set value (the thrust setting value), i.e., the instantaneous load value of the motor 30 is greater than 30%, the controller 40 controls the supporting member 20 to move (retreat relative to the clamping mechanism 51) to control the instantaneous load value of the motor 30 to decrease and maintain it at the working load value (30%).

[0040] In one embodiment of the present invention, the controller 40 stores a thrust setting lower limit value and a thrust setting upper limit value, wherein the thrust setting lower limit value is smaller than the thrust setting upper limit value. When the thrust setting value is smaller than the thrust setting lower limit value, the controller 40 searches for one of the multiple thrust values ​​using the thrust setting lower limit value. When the thrust setting value is larger than the thrust setting upper limit value, the controller 40 searches for one of the multiple thrust values ​​using the thrust setting upper limit value. For example, if the thrust setting lower limit value is 200 kg and the thrust setting upper limit value is 550 kg, when the thrust setting value is 100 kg, the controller 40 searches for one of the multiple thrust values ​​using the thrust setting lower limit value (200 kg), or when the thrust setting value is 600 kg, the controller 40 searches for one of the multiple thrust values ​​using the thrust setting upper limit value (550 kg), thereby reducing the possibility of the thrust maintaining device failing to operate due to human error.

[0041] In one embodiment of the present invention, the controller 40 is connected to an alarm device 70. The controller 40 stores information about a supporting position. The supporting member 20 is preset at the aforementioned origin position. When the controller 40 controls the motor 30 to operate and causes the screw 10 to drive the supporting member 20 to move from the origin position, the controller 40 continuously determines whether the supporting member has moved to the supporting position based on the operating status of the motor 30. When the controller 40 determines that the supporting member 20 has moved to the supporting position, the controller 40 controls the alarm device 70 to issue an alarm, wherein the alarm device 70 is selected from a group consisting of a warning light and a buzzer.

[0042] Regarding how the controller 40 determines whether the supporting member 20 has moved to the supporting position based on the operating status of the motor 30, for example, as mentioned above, in the parameter adjustment and setting stage, if the motor 30 operates at a load value of 10%, the controller 40 counts an operating time when the motor 30 starts to operate (the supporting member 20 is originally located at the origin position and separated from the workpiece W). When the supporting member 20 moves to the supporting position, the controller 40 stops counting the operating time and stores the completed operating time as a reference time. Subsequently, during the processing of the workpiece W, when the controller 40 also controls the motor 30 to operate at a load value of 10%, the supporting member 20 will move from the origin position to the supporting position, and the controller 40 simultaneously starts counting the operating time. When the controller 40 determines that the operating time is equal to the reference time, indicating that the supporting member 20 has moved to the supporting position, the controller 40 controls the alarm device 70 to issue an alarm.

[0043] It should be noted that during the parameter adjustment and setting stage and the processing of the workpiece W, if the controller 40 controls the motor 30 to operate at different load values ​​to drive the supporting member to move, the controller 40 may need to combine the lead information of the screw 10, the motor speed information of the motor 30 at different load values, etc. as a basis for judging whether the supporting member 20 has moved to the supporting position.

[0044] In this embodiment, the controller 40 stores information on a maximum moving distance. When the controller 40 determines that the supporting member 20 has moved to the supporting position, the controller 40 begins to continuously determine whether the moving distance of the supporting member 20 is equal to the maximum moving distance based on the operating status of the motor 30; when the moving distance of the supporting member is equal to the maximum moving distance, the controller controls the motor to stop running; as for how the controller 40 determines the moving distance of the supporting member 20, the method in which the controller 40 determines whether the supporting member 20 has moved to the supporting position is as described above, so it will not be repeated here.

[0045] The control method of the thrust maintaining device of the present invention is applied to the thrust maintaining device as described above. The thrust maintaining device is arranged in the CNC lathe 1 and includes the screw 10, the supporting member 20, the motor 30 and the controller 40, wherein the supporting member 20 is screwed on the screw 10, the screw is connected to the motor 30, and the motor 30 is electrically connected to the controller 40. The control method is executed by the controller 40 and is as follows Figure 5 Shown includes:

[0046] S01: storing a plurality of load values ​​of the motor 30 and a plurality of thrust values ​​of the supporting member 20 on the workpiece W.

[0047] S02: establishing a relationship between the multiple load values ​​and the multiple thrust values, wherein the multiple load values ​​correspond to the multiple thrust values ​​respectively, and the multiple load values ​​are different from each other, and the multiple thrust values ​​are different from each other.

[0048] S03 : Setting one of the multiple load values ​​as a working load value of the motor 30 .

[0049] S04: Receive a power signal from the motor 30.

[0050] S05: Calculating a real-time load value of the motor 30 when it is running according to the power signal.

[0051] S06: Continue to determine whether the instantaneous load value of the motor 30 is equal to the working load value. When the instantaneous load value of the motor 30 is equal to the working load value, the controller 40 executes step S06 again.

[0052] S07: When the instantaneous load value when the motor 30 is running is not equal to the working load value, the controller 40 controls the supporting member 20 to move so that the instantaneous load value when the motor 30 is running is equal to the working load value, so that the supporting member 20 maintains the thrust value corresponding to the working load value to support the workpiece.

[0053] The steps of the control method do not represent the execution order of the controller 40, and the specific execution method of each step is as described above and will not be repeated here. In one embodiment of the control method, the controller 40 is electrically connected to the alarm device 70, and the controller 40 stores information of a supporting position, which is defined as the position where the supporting member rests against the workpiece. The supporting member 20 is preset to be located at an origin position. When the controller 40 controls the supporting member 20 to move from the origin position, the controller 40 continuously determines whether the supporting member has moved to the supporting position based on the operating status of the motor 30. How the controller 40 determines whether the supporting member 20 has moved to the supporting position based on the operating status of the motor 30 is as described above and will not be repeated here. When the controller 40 determines that the supporting member 20 has moved to the supporting position, the controller 40 controls the alarm device 70 to issue an alarm.

[0054] In this embodiment of the control method, the controller 40 stores information on a limit moving distance, and the supporting position is between the first limit position and the second limit position. When the controller 40 determines that the supporting member 20 has moved to the supporting position, the controller 40 begins to continuously determine whether the moving distance of the supporting member 20 is equal to the limit moving distance based on the operating status of the motor 30; when the moving distance of the supporting member 20 is equal to the limit moving distance, the controller 40 controls the motor to stop running.

[0055] The thrust maintaining device and control method of the present invention have the common feature that they are both applied to a CNC lathe. The thrust maintaining device and control method thereof both store multiple load values ​​of a motor 30 and multiple thrust values ​​of a supporting member 20 on a workpiece W through a controller 40, wherein a screw 10 is provided in the CNC lathe, the supporting member 20 is provided on the screw 10, and the screw 10 is connected to the motor 30, and the motor 30 is electrically connected to the controller 40; the controller 40 calculates a real-time load value of the motor when it is running based on an electric power signal of the motor 30, and the multiple load values ​​in the controller 40 correspond to the multiple thrust values ​​respectively, and The multiple load values ​​are different from each other, and the multiple thrust values ​​are different from each other. The controller 40 uses one of the multiple load values ​​as a working load value of the motor 30, and the controller continuously determines whether the instantaneous load value is equal to the working load value. When the instantaneous load value is not equal to the working load value, the controller 40 controls the support member 20 to move so that the instantaneous load value when the motor 30 is running is equal to the working load value. The support member 20 maintains the thrust value corresponding to the working load value to support the workpiece W, so that the workpiece W can be fixed in the CNC lathe during the processing and stabilize the entire processing process, thereby improving the production yield of the workpiece W.

[0056] In summary, the foregoing merely describes the implementation methods or examples of the technical means employed by the present invention to solve the problems, and is not intended to limit the scope of the present invention. In other words, all variations and modifications that are consistent with the scope of the present invention, or equivalent variations and modifications based on the scope of the present invention, are encompassed by the scope of the present invention.

[0057] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A thrust maintaining device, applied to a CNC lathe, characterized in that: The thrust maintenance device comprises: a screw disposed in the CNC lathe; a supporting member, threadedly mounted on the screw rod, for supporting a workpiece; a motor connected to and driving the screw to rotate; a controller electrically connected to the motor, the controller receiving a power signal from the motor and calculating a real-time load value of the motor when the motor is running according to the power signal, and the controller storing a plurality of load values ​​of the motor and a plurality of thrust values ​​of the supporting member on the workpiece, the plurality of load values ​​corresponding to the plurality of thrust values, and the plurality of load values ​​being different from each other, and the plurality of thrust values ​​being different from each other; The controller uses one of the multiple load values ​​as a working load value of the motor, and continuously determines whether the instantaneous load value when the motor is running is equal to the working load value. When the instantaneous load value when the motor is running is not equal to the working load value, the controller controls the supporting member to move so that the instantaneous load value when the motor is running is equal to the working load value, and the supporting member maintains the thrust value corresponding to the working load value to support the workpiece.

2. The thrust maintaining device according to claim 1, wherein: Include: a human-machine interface electrically connected to the controller, the human-machine interface being used for inputting a thrust setting value; The controller receives the thrust setting value and searches out one of the plurality of thrust values ​​according to the thrust setting value. The load value corresponding to the thrust value is the working load value of the motor.

3. The thrust maintaining device according to claim 2, wherein: The controller stores a thrust setting lower limit value and a thrust setting upper limit value, and the thrust setting lower limit value is smaller than the thrust setting upper limit value; When the thrust setting value is less than the thrust setting lower limit value, the controller searches for one of the plurality of thrust values ​​using the thrust setting lower limit value; When the thrust setting value is greater than the thrust setting upper limit value, the controller searches out one of the plurality of thrust values ​​based on the thrust setting upper limit value.

4. The thrust maintaining device according to claim 1, wherein: Include: an alarm device electrically connected to the controller; The controller stores information about a supporting position, where the supporting position is defined as the position where the supporting member abuts against the workpiece. The supporting member is preset to be located at an origin position. When the controller controls the supporting member to move from the origin position, the controller continuously determines whether the supporting member has moved to the supporting position based on the operating state of the motor. When the controller determines that the holding member moves to the holding position, the controller controls the alarm to issue an alarm.

5. The thrust maintaining device according to claim 4, characterized in that: The controller stores information on a limit movement distance. When the controller determines that the supporting member has moved to the supporting position, the controller begins to continuously determine whether the moving distance of the supporting member is equal to the limit movement distance based on the operating state of the motor. When the moving distance of the supporting member is equal to the limit moving distance, the controller controls the motor to stop running.

6. The thrust maintaining device according to claim 4, wherein: The warning device is selected from the group consisting of a warning light and a buzzer.

7. A method for controlling a thrust maintaining device, characterized in that: The invention is applied to a thrust maintaining device, which is installed in a CNC lathe and includes a screw, a supporting member, a motor, and a controller, wherein the supporting member is screwed onto the screw, the screw is connected to the motor, and the motor is electrically connected to the controller. The control method is executed by the controller and includes: storing a plurality of load values ​​of the motor and a plurality of thrust values ​​of the supporting member on a workpiece; Establishing a relationship between the plurality of load values ​​and the plurality of thrust values, wherein the plurality of load values ​​correspond to the plurality of thrust values ​​respectively, and the plurality of load values ​​are different from each other, and the plurality of thrust values ​​are different from each other; Setting one of the plurality of load values ​​as a working load value of the motor; receiving a power signal from the motor; Calculating a real-time load value of the motor when it is running according to the power signal; Continuously determining whether the instantaneous load value of the motor when it is running is equal to the working load value; When the instantaneous load value when the motor is running is not equal to the working load value, the controller controls the supporting member to move so that the instantaneous load value when the motor is running is equal to the working load value, and the supporting member maintains the thrust value corresponding to the working load value to support the workpiece.

8. The method for controlling a thrust maintaining device according to claim 7, wherein: The controller is electrically connected to an alarm device and stores information about a supporting position. The supporting position is defined as a position where the supporting member abuts against the workpiece. The supporting member is preset to be located at an origin position. When the controller controls the supporting member to move from the origin position, the controller continuously determines whether the supporting member has moved to the supporting position based on the operating state of the motor. When the controller determines that the holding member moves to the holding position, the controller controls the alarm to issue an alarm.

9. The method for controlling a thrust maintaining device according to claim 8, wherein: The controller stores information on a limit movement distance. When the controller determines that the supporting member has moved to the supporting position, the controller begins to continuously determine whether the movement distance of the supporting member is equal to the limit movement distance based on the operating state of the motor. When the moving distance of the supporting member is equal to the limit moving distance, the controller controls the motor to stop running.

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