阅读说明：本技术 机床及工件测量方法 (Machine tool and workpiece measuring method ) 是由 贺来则夫 于 2018-12-21 设计创作，主要内容包括：本发明是提高工件直径的测量精度。本发明的机床具备：位移传感器,搭载在导套或支撑部的至少一方,所述导套在主轴的前方支撑由所述主轴固持的工件,所述支撑部支撑所述主轴；以及运算部,基于所述位移传感器对加工后的所述工件的测量值而运算加工后的所述工件的直径。所述主轴可沿轴向进行前后移动,通过加工所述工件后的所述主轴的后退使所述工件的被加工部位向所述轴向上的所述位移传感器的特定测量位置移动,由所述位移传感器对所述移动后的所述工件的被加工部位进行测量。(The invention improves the measurement accuracy of the diameter of the workpiece. A machine tool of the present invention includes: a displacement sensor mounted on at least one of a guide sleeve supporting a workpiece held by a main shaft in front of the main shaft or a support supporting the main shaft; and a calculation unit that calculates the diameter of the workpiece after machining based on the measurement value of the workpiece after machining by the displacement sensor. The spindle can move back and forth along the axial direction, the machined part of the workpiece moves to a specific measuring position of the displacement sensor in the axial direction through the retreating of the spindle after the workpiece is machined, and the machined part of the workpiece after moving is measured by the displacement sensor.)

1. A machine tool is characterized by comprising:

a displacement sensor mounted on at least one of a guide sleeve supporting a workpiece held by a main shaft in front of the main shaft or a support supporting the main shaft; and

and a calculation unit that calculates the diameter of the workpiece after machining based on the measurement value of the workpiece after machining by the displacement sensor.

2. The machine tool of claim 1, wherein: the spindle is movable back and forth in an axial direction, a portion to be machined of the workpiece is moved to a specific measurement position of the displacement sensor in the axial direction by the retraction of the spindle after machining the workpiece, and the moved portion to be machined of the workpiece is measured by the displacement sensor.

3. The machine tool of claim 1 or 2, wherein: the guide sleeve includes a non-rotating cylindrical non-rotating portion and a rotating portion that is rotatable inside the non-rotating portion in synchronization with rotation of the spindle and supports the workpiece; and is

The rotating portion has a through hole for exposing a part of the workpiece to be supported,

the displacement sensor mounted on the non-rotating portion measures the workpiece through the through hole.

4. The machine tool of claim 1 or 2, wherein: the support portion is configured to be attachable to and detachable from the guide bush, and the displacement sensor mounted on the support portion measures the workpiece held by the spindle in a state where the guide bush is detached from the support portion.

5. The machine tool of any one of claims 1 to 4, wherein: further comprising a temperature sensor for measuring a temperature near a position where the displacement sensor is mounted; and is

The calculation unit corrects the measurement value of the displacement sensor based on the measurement value of the temperature sensor, and calculates the diameter based on the corrected measurement value of the displacement sensor.

6. A workpiece measuring method is characterized by comprising:

a measuring step of measuring the processed workpiece by a displacement sensor, wherein the displacement sensor is carried on at least one of a guide sleeve or a supporting part, the guide sleeve supports the workpiece fixed by the main shaft in front of the main shaft, and the supporting part supports the main shaft; and

and an operation step of calculating the diameter of the workpiece after machining based on the measurement value obtained in the measurement step.

Technical Field

The invention relates to a machine tool and a workpiece measuring method.

Background

In the field of machine tools, methods for measuring the diameter of a workpiece have been disclosed (see patent documents 1, 2, and 3).

In document 1, an NC (Numerical Control) lathe mounts a measuring instrument on one surface of a turret tool post, and detects the diameter of a workpiece by bringing a touch sensor of the measuring instrument into contact with the workpiece.

In document 2, a workpiece diameter measuring device provided with a laser measuring instrument is mounted on a tool bed on which all of a headstock, a tool rest, an opposing spindle, and a turret-type tool rest are mounted.

In document 3, a measuring instrument for measuring the diameter of a workpiece measures the size of a clamped portion by clamping a measurement object between a pair of measuring claws.

Disclosure of Invention

[ problems to be solved by the invention ]

In documents 1 and 2, the positional relationship between the measuring instrument and the workpiece is unstable due to the influence of thermal displacement generated by the measuring instrument and the workpiece or by a plurality of structures (e.g., a tool post, a headstock, etc.) present on a path connecting the measuring instrument and the workpiece, because the measuring instrument and the object to be measured (the workpiece) are located at a relatively long distance. Therefore, the measurement result of the workpiece diameter is liable to generate an error. In the case of the configuration of document 3 in which the measurement object is sandwiched between the pair of measurement claws to measure the diameter, measurement errors are likely to occur between the pair of measurement claws in an environment where a large amount of chips of the workpiece are generated like a lathe, and it is difficult to measure the diameter of the workpiece with high accuracy.

The present invention has been made in view of the above problems, and provides a machine tool and a workpiece measuring method for accurately measuring the diameter of a workpiece.

[ means for solving problems ]

One aspect of the present invention is a machine tool including: a displacement sensor mounted on at least one of a guide sleeve supporting a workpiece held by a main shaft in front of the main shaft or a support supporting the main shaft; and a calculation unit that calculates the diameter of the workpiece after machining based on the measurement value of the workpiece after machining by the displacement sensor.

According to the above configuration, the displacement sensor is mounted on at least one of a guide bush supporting the workpiece or a support portion supporting the spindle. That is, the distance between the displacement sensor and the workpiece is short, and the environments of the displacement sensor and the workpiece are almost the same. Therefore, the measurement result (calculation result) of the workpiece diameter with less error can be obtained.

In one aspect of the present invention, the spindle may be movable back and forth in an axial direction, the spindle may be moved back after the workpiece is machined to move a portion to be machined of the workpiece to a specific measurement position of the displacement sensor in the axial direction, and the displacement sensor may measure the moved portion to be machined of the workpiece.

According to the above configuration, the workpiece to be machined can be accurately measured by the displacement sensor.

In one aspect of the present invention, the guide bush may include a non-rotating cylindrical non-rotating portion and a rotating portion that is rotatable inside the non-rotating portion in synchronization with rotation of the spindle and supports the workpiece, the rotating portion may include a through hole that exposes a part of the supported workpiece, and the displacement sensor mounted on the non-rotating portion may measure the workpiece through the through hole.

According to the above configuration, the displacement sensor mounted on the non-rotating portion of the guide bush can measure the machined workpiece through the through hole provided in the rotating portion.

In one aspect of the present invention, the support portion may be configured to detachably mount the guide bush, and the displacement sensor mounted on the support portion may measure the workpiece held by the spindle in a state where the guide bush is detached from the support portion.

According to the above configuration, the displacement sensor mounted on the support portion can measure the machined workpiece held by the spindle supported by the support portion.

In one aspect of the present invention, the machine tool may further include a temperature sensor that measures a temperature near a position where the displacement sensor is mounted, and the calculation unit may correct the measurement value of the displacement sensor based on the measurement value of the temperature sensor and calculate the diameter based on the corrected measurement value of the displacement sensor.

According to the above configuration, the calculation unit can correct the fluctuation of the measurement value of the displacement sensor due to the temperature influence based on the measurement value of the temperature sensor, thereby calculating the diameter of the workpiece after machining more accurately.

The technical idea of the present invention is also realized by an object other than a machine tool.

For example, a workpiece measuring method can be grasped as an invention, and the workpiece measuring method includes: a measuring step of measuring the processed workpiece by a displacement sensor, wherein the displacement sensor is carried on at least one of a guide sleeve or a supporting part, the guide sleeve supports the workpiece fixed by the main shaft in front of the main shaft, and the supporting part supports the main shaft; and an operation step of calculating the diameter of the workpiece after machining based on the measurement value of the measurement step. Further, a program for realizing the method or a computer-readable storage medium storing the program may be established as the invention, respectively.

Drawings

Fig. 1 is a diagram simply showing the configuration of an NC lathe.

Fig. 2 is a block diagram simply showing the electrical connection relationship of the NC lathe.

Fig. 3 is a flowchart showing a process of measuring the diameter of a workpiece after machining.

Fig. 4 is a diagram for explaining the displacement sensor according to embodiment 1.

Fig. 5 is a view showing the guide bush in a simplified manner from a front side in the Z-axis direction.

Fig. 6 is a diagram for explaining a displacement sensor according to embodiment 2.

Fig. 7 is a flowchart showing a process of measuring the diameter of a workpiece after machining according to embodiment 2.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are only for the purpose of illustrating the present embodiment. Further, since the drawings are illustrative, the shapes, the proportions, and the like may not coincide with each other.

1. Description of the apparatus constitution:

fig. 1 shows a simplified example of an nc (numerical control) lathe 10 according to the present embodiment. The NC lathe 10 is one type of machine tool. The NC lathe 10 includes a NC (numerical control) device 11 as a computer, and machines a workpiece W by numerically controlling each part (machining part) that operates to machine the workpiece W, such as the main spindle 52, by the NC device 11. The workpiece measuring method is realized by at least a part of the structure included in the NC lathe 10.

The machining unit of the NC lathe 10 includes, for example, a spindle 52, a headstock 53 on which the spindle 52 is mounted, a tool rest 43, a Guide Bush (GB)20, a GB support 30, and an actuator 61. The spindle stock 53 is movable together with the spindle 52 in the axial (Z-axis) direction of the spindle 52. The Z axis is oriented in the left-right direction in fig. 1. For convenience, the positive side in the Z-axis direction (the right side in fig. 1) is referred to as "front", and the negative side in the Z-axis direction (the left side in fig. 1) is referred to as "rear". The main spindle 52 includes a chuck (see reference numeral 57 in fig. 6) at a distal end portion thereof, and the chuck releasably holds a rod-shaped workpiece W supplied to the Z axis from behind the main headstock 53.

The main shaft 52 rotates about the Z axis. The portion indicated by reference numeral 52 in fig. 1 includes a spindle which holds the workpiece W and is rotatable about the Z axis, a cylindrical member which encloses the spindle and does not rotate, and the like, and such a portion is also referred to as a spindle structure. That is, the spindle 52 may also be interpreted as referring to a spindle structure.

In front of the main shaft 52, a GB support 30 is provided. The GB support 30 is fixed in the processing portion of the NC lathe 10. GB support 30 has through hole 31 penetrating in the Z direction in a range including the Z axis, and GB20 is attached corresponding to through hole 31. GB20 is a member that is detachable from GB support 30, and is attached to GB support 30 by, for example, partially fitting into through-hole 31 of GB support 30. Fig. 1 shows a state in which GB20 is attached (supported) to GB support 30. As shown in fig. 1, workpiece W protruding forward from spindle 52 further protrudes forward through GB support 30 and GB 20. GB20 supports from the periphery a workpiece W on the Z axis that penetrates GB20 and projects forward.

A tool 43a for machining a workpiece W protruding forward from GB support 30 (in the example of fig. 1, protruding forward from GB 20) is attached to tool post 43. A plurality of tools including a front-face machining tool bit and a cutting tool bit may be attached to the tool holder 43 at the same time, or these tools may be attached so as to be replaceable. The X-axis direction in which the tool post 43 moves is perpendicular to the Z-axis direction, and is directed vertically in fig. 1. The Y-axis direction in which the tool post 43 moves is a direction perpendicular to the X-axis direction and the Z-axis direction (a direction perpendicular to the paper surface of fig. 1). Although the tool holder 43 is separated from the GB support portion 30 in fig. 1, the tool holder 43 may be supported by the GB support portion 30 in a movable state in the X-axis direction and the Y-axis direction, for example. Alternatively, GB support 30 may also serve as a structure for supporting a not-shown tool holder different from tool holder 43.

In the example of fig. 1, the actuator 61 moves the linearly moving body 64 along the screw shaft 63 of the ball screw mechanism 62 parallel to the Z-axis direction by operating the ball screw mechanism 62. Since the linearly moving body 64 of the ball screw mechanism 62 is directly or indirectly fixed to the spindle stock 53, the spindle stock 53 and the spindle 52 mounted on the spindle stock 53 move forward and backward in the Z-axis direction together with the linearly moving body 64. The actuator 61 is a motor (servo motor, linear motor, etc.) serving as a power source of the ball screw mechanism 62. However, the ball screw mechanism 62 is only one mechanism for moving the spindle base 53 and the spindle 52 in the Z-axis direction. For example, the actuator 61 may move the headstock 53 and the main shaft 52 in the Z-axis direction by operating a cylinder that performs linear motion hydraulically or electrically.

Fig. 2 is a block diagram showing electrical connection between the respective parts of the NC lathe 10. The NC device 11 includes, for example, a CPU (Central Processing Unit) 11a, a RAM (Random access Memory) 11b, and a ROM (Read Only Memory) 11c as controllers. The servo amplifier 40, the spindle amplifier 50, the servo amplifier 60, the displacement sensor 70, and the like are communicably connected to the NC apparatus 11 via the bus 11 d. The servo amplifier 40 is connected to the X-axis motor 41 and the Y-axis motor 42, respectively, and supplies power to the motors 41 and 42 connected thereto. The X-axis motor 41 and the Y-axis motor 42 are connected to the tool post 43, and convert supplied electric power into power for moving the tool post 43, thereby moving the tool post 43 in the X-axis direction and the Y-axis direction, respectively.

The servo amplifier 60 is connected to the actuator 61, and supplies electric power to the actuator 61. The spindle amplifier 50 is connected to a spindle motor 51, and supplies electric power to the spindle motor 51. The spindle motor 51 is connected to the spindle 52. The spindle motor 51 converts the supplied electric power into power to rotate the spindle 52, thereby rotating the spindle 52. Further, an actuator (not shown) for opening and closing the chuck 57 provided in the spindle 52 is also controlled by the NC apparatus 11.

In the NC apparatus 11, the CPU11a executes processing in accordance with the machining program P using the RAM11b as a work area, and numerically controls power supply to the amplifiers 40, 50, and 60, for example. As a result, the machining of the workpiece W by the NC lathe 10 is realized, and a product is manufactured from the workpiece W. The machining program P is composed of various instructions. The NC apparatus 11 includes an operation receiving unit 12, a display unit 13, and the like. The operation receiving unit 12 may be configured by a plurality of buttons, keys, or the like for receiving input operations by the user, and includes a touch panel on the display unit 13. The display unit 13 is a display for displaying various numerical values and setting contents input by the user via the operation receiving unit 12, and various information on the NC lathe 10 on a screen.

The displacement sensor 70 is mounted on at least one of GB20 which supports the workpiece W held by the main shaft 52 in front of the main shaft 52, and a support portion which supports the main shaft 52. The support portion for supporting the spindle 52 corresponds to the GB support portion 30 in the example of fig. 1. Specific examples of the mounting position of the displacement sensor 70 will be described later with reference to fig. 4 to 6.

Of course, the configuration of the NC lathe 10 is not limited to the above. For example, the direction in which the tool holder 43 is movable is not limited to the above-described direction. The NC lathe 10 may include a back spindle or the like that rotatably holds the front end of the workpiece W protruding forward from the spindle 52.

2. Measuring and processing the diameter of the processed workpiece:

fig. 3 is a flowchart showing the measurement processing of the workpiece diameter after machining performed by the NC apparatus 11(CPU11a) according to the machining program P in the present embodiment. As described above, the NC apparatus 11 realizes the machining of the workpiece W by the NC lathe 10 (machining unit) by executing the processing based on the various commands constituting the machining program P. The measurement processing of the diameter of the workpiece after machining is processing incorporated into the machining processing of the workpiece W according to such a machining program P. That is, a command corresponding to the measurement processing of the diameter of the workpiece after machining is also incorporated into the machining program P. The NC apparatus 11 starts the measurement processing of the diameter of the workpiece after machining by executing a command corresponding to the measurement processing of the diameter of the workpiece after machining. The time when the measurement processing of the workpiece diameter after machining is started is a specific time when the machining processing of the workpiece W is started.

The time when the measurement processing of the diameter of the workpiece after machining is started is, for example, a time when a certain time (for example, several tens of minutes) has elapsed after the measurement processing of the diameter of the workpiece after the previous machining is performed. That is, the NC apparatus 11 periodically performs a measurement process of a diameter of a workpiece after machining, in machining (manufacturing a product from the workpiece W) the workpiece W by repeatedly using the machining portion on a product-by-product basis. The specific time may be a time when a specific number (for example, several tens) of products are produced from the workpiece W after the measurement processing of the workpiece diameter is performed after the previous processing, for example. Further, the NC apparatus 11 may start the measurement process of the diameter of the workpiece after machining at a point in time when the machining process of the workpiece W is stopped in response to an instruction from a user or the like, and the machining of the workpiece W is first completed after the machining process is restarted (the 1 st product after the restart is manufactured). The machining program P is configured to execute a command corresponding to the measurement process of the diameter of the machined workpiece at the specific timing.

After the measurement processing of the diameter of the machined workpiece is started, the NC apparatus 11 first moves the machined workpiece W to a specific measurement position of the displacement sensor 70 (step S100). Currently, the distal end portion of the workpiece W is in a state after being machined by the tool 43a or the like (and in a state before the machined distal end portion is separated from the workpiece W). The distal end portion of the workpiece W after being machined by the tool 43a or the like is also referred to as a workpiece of the workpiece W. The NC apparatus 11 naturally grasps the position of the portion to be processed of the workpiece W in the Z-axis direction. In step S100, the NC apparatus 11 operates the actuator 61 via the servo amplifier 60 to move the spindle base 53 and the spindle 52 backward. Since the workpiece W is held by the chuck 57 of the spindle 52, the workpiece W moves rearward together with the spindle 52. At this time, the NC apparatus 11 moves the spindle base 53 and the spindle 52 backward until the workpiece W reaches a specific position on the Z axis predetermined as the measurement position.

After the movement in step S100, the NC apparatus 11 measures the workpiece W after the machining, that is, the part to be machined, with the displacement sensor 70, and obtains the measurement result (measurement value) of the displacement sensor 70 (step S110). Step S110 corresponds to one of the measurement steps of the present invention.

The displacement sensor 70 performs measurement of the workpiece W in an operable state, for example, all the time or repeatedly. Therefore, the NC apparatus 11 can acquire the measurement value of the displacement sensor 70 at the time of step S110, and thereby acquire the measurement value of the workpiece W after the machining by the displacement sensor 70.

The NC apparatus 11 calculates the diameter of the workpiece W after machining (the workpiece diameter after machining) based on the measurement value acquired in step S110 (step S120). Step S120 corresponds to the calculation step of the present invention. In order to execute step S120, the NC apparatus 11 can be said to function as an arithmetic unit. From the above, it is considered that the measurement of the diameter of the workpiece after the machining is completed. However, in the example of fig. 3, the NC apparatus 11 executes step S130 after step S120.

In step S130, the NC apparatus 11 calculates a machining error of the workpiece W based on the machined workpiece diameter calculated in step S120. The NC apparatus 11 has a target value "d 2" of the post-machining workpiece diameter "d 1" as information. The target value d2 is a value set in advance by a user operating the operation receiving unit 12, for example. Therefore, the NC apparatus 11 sets the difference | d1-d2| between the post-machining workpiece diameter d1 calculated in step S120 and the target value d2 as the machining error of the workpiece W. After the calculation of the machining error is completed in this manner, the NC apparatus 11 completes the flowchart of fig. 3 (measurement processing of the workpiece diameter after machining), and returns to the machining processing of the workpiece W.

The NC apparatus 11 can correct the machining process after the return based on the calculated machining error. That is, the NC apparatus 11 corrects the numerical value settings relating to the operation of the processing portion, such as the movement amount of the tool rest 43, based on the machining error so that the machining error approaches 0 in the subsequent machining of the workpiece W. The calculated machining error can be said to be a machining error resulting from combining the thermal displacements of the respective portions constituting the machining section. Therefore, the correction based on the calculated machining error is also referred to as thermal displacement correction.