Machine tool for machining high-precision hole positions and its control method

Abstract

To provide a high precision drilling machine tool capable of drilling a workpiece according to required workpiece precision.SOLUTION: A high precision drilling machine tool 10 configured to perform high precision drilling at a predetermined position, comprises: support means 12 configured to support a table 11 on which a drilling object workpiece is placed; moving means 13 for moving the support means 12 in a predetermined axial direction; detection means 14 configured to detect position information of a master target 11b provided on the table 11; and machining means 15 for drilling the workpiece. The master target 11b is provided at a position where high precision drilling is determined to be performed in advance. When precision of positioning a drill hole at a drilling object part of the workpiece is equal to or higher than a predetermined Level, the machining means 15 performs drilling on the workpiece on the basis of position information of the master target 11b detected by the detection means 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a machine tool that processes a workpiece according to required workpiece accuracy and a control method thereof.

Background Art

[0002] In the feed drive system control methods of machine tools such as lathes, boring machines, and machining centers, closed-loop control, which is a feedback control system, is used. Here, closed-loop control is roughly divided into full closed-loop control and semi-closed-loop control. The full closed-loop control disclosed in Patent Document 1 is a control method in which a scale is directly attached to a table of a machine tool or the like, the position of a workpiece to be processed is detected, and the position information is fed back. On the other hand, semi-closed-loop control is a control method in which the position of a workpiece to be processed is detected based on the rotation angle of the shaft of a servo motor, and the position information is fed back.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, although the full closed-loop control as disclosed in Patent Document 1 can grasp the position information of a workpiece with high accuracy, for example, in a case where a large number of hole drilling operations are required for one workpiece, a large number of man-hours are required for each hole drilling operation. Further, semi-closed-loop control can shorten the data processing time compared to full closed-loop control, but the position accuracy of hole drilling does not reach a level that can satisfy the required workpiece accuracy.

[0005] In view of the above problems, the present invention aims to provide a machine tool for high-precision hole position machining that can machine a workpiece according to the required workpiece precision, and a control method therefor.

Means for Solving the Problems

[0006] The machine tool for high-precision hole position machining of the present invention, which is made to solve the above problems, is a machine tool for high-precision hole position machining that drills holes at a predetermined position where high-precision hole drilling is pre-determined, and includes a support means for supporting a table on which a workpiece to be drilled is placed, a moving means for moving the support means in a predetermined axial direction, a detecting means for detecting the position information of a master target provided on the table, and a machining means for performing a machining operation on the workpiece. The master target is provided at a position where high-precision hole drilling is pre-determined, and the machining means drills the workpiece based on the position information of the master target detected by the detecting means when the machining hole positioning accuracy of the workpiece to be machined is at a predetermined level or higher. With this configuration, the workpiece can be machined according to the required workpiece precision.

[0007] Further, in the machine tool for high-precision hole position machining of the present invention, the detecting means calculates a correction value based on the temperature information of the master target, and corrects the position information of the master target with the correction value. With this configuration, the influence on positioning due to temperature changes in the machining situation can be reduced.

[0008] Further, a control method for a machine tool for high-precision hole position machining according to the present invention includes a support means for supporting a table on which a workpiece to be machined such as drilling is placed on its surface, a moving means for moving the support means in a predetermined axial direction, a detecting means for detecting position information of a master target provided on the surface of the table, and a machining means for performing a machining operation on the workpiece. The control method for a machine tool for high-precision hole position machining is characterized by including: a step in which the detecting means detects the position information of the master target; a step in which the detecting means detects the temperature information of the master target; a step in which the detecting means calculates machining information of the workpiece based on the position information of the master target and the temperature information of the master target; and a step in which the machining means machines the workpiece based on the machining information of the workpiece when the machining hole positioning accuracy of the workpiece to be machined is at a predetermined level or higher. With this configuration, it is possible to reduce the influence of temperature changes in the machining situation on positioning, and it is possible to machine the workpiece according to the required workpiece accuracy.

Effects of the Invention

[0009] For a machine tool for high-precision hole position machining according to the present invention, for a portion where high-precision machining is required, high-precision machining required can be performed based on the position information of the master target.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 5

Best Mode for Carrying Out the Invention

[0011] Hereinafter, the machine tool for high-precision hole position machining according to the embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is an overall view of the machine tool for high-precision hole position machining according to the embodiment of the present invention. Further, FIG. 2 is an overall view showing a state in which a workpiece W to be machined is placed on a table related to the machine tool for high-precision hole position machining according to the embodiment of the present invention. Furthermore, FIG. 3 is an overall view showing a state in which the detection means related to the machine tool for high-precision hole position machining according to the embodiment of the present invention detects the position information of the master target. Also, FIG. 4 is an overall view showing a state in which the machining means related to the machine tool for high-precision hole position machining according to the embodiment of the present invention machines the workpiece.

[0012] The basic configuration of the machine tool 10 for high-precision hole position machining according to the embodiment of the present invention is a so-called semi-closed loop controlled machine tool. The machine tool 10 for high-precision hole position machining according to the present embodiment includes a support means 12 that supports a table 11 on which a workpiece W to be drilled is placed, a moving means 13 that moves the support means 12 in a predetermined axial direction, a detection means 14 that detects the position information of a master target 11b provided on the table 11, and a machining means 15 that performs a machining operation on the workpiece W.

[0013] The workpiece W is an object to be machined such as drilling by the machine tool 10 for high-precision hole position machining, and its shape, material, etc. are not particularly limited. For example, the workpiece W is an engine part of an automobile, and its material is carbon steel or the like. Further, there is one or more locations where drilling is required for each workpiece W, and the required machining hole position accuracy is determined in advance for each.

[0014] Table 11 is formed in a flat plate shape so that a workpiece W to be processed such as drilling can be placed on the surface 11a. Further, as shown in FIG. 1, on the surface 11a of the table 11, a master target 11b corresponding to each workpiece W is provided. In the present embodiment, the master target 11b is formed in a hole portion or a protrusion shape at a position corresponding to a drilling position where the machining hole positioning accuracy set for the workpiece W is at a predetermined level or higher. Further, since the master target 11b is formed at different positions for each workpiece W, it is preferable that the table 11 can be replaced according to the workpiece for which drilling is performed.

[0015] Also, it is preferable that a reference mark indicating a reference when placing the workpiece W is provided on the surface 11a of the table 11. Further, the table 11 may be provided with a fixture for holding the placed workpiece W.

[0016] The support means 12 supports the table 11 on which the workpiece W to be processed such as drilling is placed. The support means 12 preferably has a configuration in which the table 11 on which the master target 11b is formed can be removed according to the workpiece W for which drilling is performed.

[0017] The moving means 13, for example, a servo motor, can move the table 11 on which the workpiece W is placed by passing through a conversion unit 16 that converts the rotation of the shaft of the servo motor into movement in the axial direction.

[0018] The detection means 14 is, for example, a wireless signal transmission type touch probe, and detects a processing position such as a drilling process on the workpiece W. In the present embodiment, if the master target 11b formed on the table 11 is a hole, the detection means 14 slides along the inner diameter thereof to detect position information such as the center position and diameter of the master target 11b. Further, if the master target 11b formed on the table 11 is a protrusion shape, the detection means 14 slides along the outer diameter thereof to detect position information such as the center position and diameter of the master target 11b. Then, the detection means 14 transmits the detected position information of the master target 11b to a storage unit 22 described later.

[0019] Further, the detection means 14 slides along the shape of the processed portion of the workpiece W to detect position information of the processed portion of the workpiece W. Then, the detection means 14 transmits the detected position information of the processed portion of the workpiece W to the storage unit 22 described later.

[0020] Furthermore, the detection means 14 detects temperature information of the master target 11b, calculates a temperature correction value based on the detected temperature information of the master target 11b, corrects the position information of the master target 11b based on the temperature correction value, and transmits it to the storage unit 22 described later as thermally corrected position information.

[0021] The processing means 15 performs processing such as drilling on the workpiece W. In the present embodiment, the processing means 15 includes an arm having a plurality of joints, a mounting portion to which a processing tool such as a drill is attached to the tip of the arm, and a driving portion that moves the processing tool to the processed portion of the workpiece W. Then, the processing means 15 moves the processing tool to the processed portion of the workpiece W and performs processing on the workpiece W, for example, drilling.

[0022] Here, when the machining hole positioning accuracy of the machined portion of the workpiece W is equal to or higher than a predetermined level, the machining means 15 machines the workpiece W based on the position information of the master target 11b detected by the detection means 14.

[0023] In this embodiment, the machining hole positioning accuracy of the machining location of the workpiece W is predetermined. The machining means 15 determines whether the machining hole positioning accuracy of the machining location of the workpiece W is equal to or higher than a predetermined level. When the machining hole positioning accuracy of the machining location of the workpiece W is equal to or higher than the predetermined level, the machining means 15 calculates the error between the position information of the master target 11b detected by the detection means 14 and the position information of the machining location of the workpiece W corresponding to the position information of the master target 11b. Next, the machining means 15 corrects the machining information of the workpiece W stored in the storage unit 23 based on the calculated error to obtain the corrected machining information of the workpiece W. Then, the machining means 15 performs drilling on the workpiece W based on the corrected machining information of the workpiece W. Here, the machining information of the workpiece W includes the corrected position information of the machining location of the workpiece W, the diameter, and the machining hole positioning accuracy of the machining location, etc.

[0024] In this way, based on the position information of the master target 11b detected by the detection means 14, the machining information of the workpiece W is corrected, and by performing drilling on the workpiece W, the machining accuracy can be suppressed to an error of ±0.03 mm (Cp 1.33). Here, "Cp", that is, the process capability index, is one of the indicators for quantitatively evaluating the process capability of a certain process in the field of quality control. In this specification, it is calculated as ±1σ (about 70%) at the center of the tolerance range. Note that the machining accuracy guaranteed by general semi-closed loop control is ±0.04 mm to ±0.05 mm.

[0025] Furthermore, the machining means 15 may calculate a temperature correction value based on the detected temperature information of the master target 11b, correct the position information of the master target 11b with the temperature correction value, correct the machining information of the workpiece W based on the corrected position information of the master target 11b, and obtain the thermal displacement correction machining information of the workpiece W. Then, the machining means 15 may perform drilling on the workpiece W based on the thermal displacement correction machining information of the workpiece W.

[0026] When the workpiece W to be drilled is carbon steel, the linear expansion coefficient of carbon steel is 12.18×10 -6Since it is in / °C, for example, when the temperature difference is 20°C, the maximum allowable deviation amount between the position of the machining hole of the work W and the position information of the master target 11b is set to be within 4 mm.

[0027] On the other hand, when the machining hole positioning accuracy at the machining location of the work W is less than a predetermined level, the machining means 15 performs drilling on the work W based on the machining information of the work W stored in the storage unit 22.

[0028] Moreover, it is preferable that the machine tool 10 for high-precision hole position machining according to the present embodiment has a cooling means for maintaining the temperature of the machining means 15 within a constant temperature range (for example, within ±2°C). By having the cooling means, the error generated in the machining means 15 due to temperature changes can be suppressed.

[0029] Furthermore, as shown in FIG. 2, the machine tool 10 for high-precision hole position machining includes a control unit 21 that controls each of the support means 12, the moving means 13, the detection means 14, and the machining means 15, a storage unit 22 that stores a control program for controlling each means and various data, an input reception unit 23 that receives an input from an operator, and a warning unit 24.

[0030] The control unit 21 is a CPU or the like, and controls each of the support means 12, the moving means 13, the detection means 14, and the machining means 15 by executing various programs stored in the storage unit 22.

[0031] The storage unit 22 is a RAM, a ROM, and other storage devices, and stores an operation program for controlling each of the support means 12, the moving means 13, the detection means 14, and the machining means 15. In addition, the storage unit 22 stores machining information of the work W including position information, diameter, machining hole positioning accuracy, and linear expansion coefficient for each material for each machining location of the work W. Furthermore, the storage unit 22 also stores machining order information for a plurality of machining locations of the work W.

[0032] The input reception unit 23 is a keyboard, a display (not shown), or a touch panel display, and receives information input by an operator, such as the position information of the machining location of the workpiece W and the machining hole positioning accuracy of the machining location.

[0033] When a problem occurs in the drilling process for the workpiece W, the warning unit 24 gives a warning by sound or light to notify the operator or the like.

[0034] The drilling procedure for the workpiece W by the machine tool 10 for high-precision hole position machining according to the present embodiment having the above-described configuration will be described below.

[0035] First, the workpiece W to be drilled is placed on the surface 11a of the table 11 in alignment with the reference mark. By placing the workpiece W in alignment with the reference mark, it is preferable that the drilling location requiring high-precision machining hole positioning accuracy can be placed so that the master target 11b substantially coincides.

[0036] Next, with the workpiece W placed on the table 11, the detection means 14, for example, the tip of a wireless signal transmission type touch probe, is slid along the inner diameter of the master target 11b to detect the position information such as the center position and diameter of the master target 11b. Then, the detection means 14 transmits the detected position information of the master target 11b to a storage unit 23 (not shown).

[0037] Further, the detection means 14 may detect the temperature information of the master target 11b, calculate a temperature correction value based on the detected temperature information of the master target 11b, correct the position information of the master target 11b based on the temperature correction value, and obtain the thermally corrected position information of the master target 11b.

[0038] Then, when the machining hole positioning accuracy of the machining location of the workpiece W is at a predetermined level or higher, the machining means 15 machines the workpiece W based on the position information of the master target 11b detected by the detection means 14.

[0039] Specifically, since the machining hole positioning accuracy of the machining location of the workpiece W is predetermined, the machining means 15 determines whether the machining hole positioning accuracy of the machining location of the workpiece W is at or above a predetermined level. When the machining hole positioning accuracy of the machining location of the workpiece W is at or above the predetermined level, the machining means 15 calculates the error between the position information of the master target 11b detected by the detection means 14 and the position information of the machining location of the workpiece W corresponding to the position information of the master target 11b. Next, the machining means 15 corrects the machining information of the workpiece W stored in the storage unit 23 based on the calculated error to obtain corrected machining information for the workpiece W. Then, the machining means 15 performs drilling on the workpiece W based on the corrected machining information for the workpiece W.

[0040] In this embodiment, by correcting the machining information of the workpiece W based on the position information of the master target 11b detected by the detection means 14 and performing drilling on the workpiece W, the machining accuracy can be suppressed to an error of ±0.03 mm (Cp 1.33).

[0041] Note that the machining means 15 may correct the machining information of the workpiece W based on the thermal correction position information of the master target 11b to obtain thermal displacement correction machining information for the workpiece W. Then, the machining means 15 may perform drilling on the workpiece W based on the thermal displacement correction machining information for the workpiece W.

[0042] Also, when the machining hole positioning accuracy at the machining location of the workpiece W is less than the predetermined level, the machining means 15 performs drilling on the workpiece W based on the machining information of the workpiece W stored in the storage unit 22.

[0043] Since the machine tool 10 for high-precision hole position machining according to this embodiment can perform drilling according to the machining hole positioning accuracy preset for each machining location of the workpiece W, the machining accuracy of the workpiece is ensured. Also, the machine tool 10 for high-precision hole position machining according to this embodiment can perform drilling that suppresses the influence of temperature changes in the workpiece W.

[0044] Since the machine tool 10 for high-precision hole position machining according to the present embodiment corrects the machining information of the workpiece W only when the machining hole positioning accuracy preset for each machined portion of the workpiece W is equal to or higher than a predetermined level, it is possible to improve the machining processing speed and reduce the manufacturing cost as compared with a full-closed control machine tool that corrects the machining information of the workpiece W at all machined portions of the workpiece W.

[0045] The invention disclosed in this specification, in addition to the configurations of the respective inventions and embodiments, within an applicable range, those obtained by changing these partial configurations to other configurations disclosed in this specification and specifying them, or those obtained by adding other configurations disclosed in this specification to these configurations and specifying them, or those obtained by deleting these partial configurations to the extent that partial operational effects can be obtained and conceptually generalizing them are included.

Explanation of Reference Numerals

[0046] 10... Machine tool for high-precision hole position machining 11... Table 11a... Surface 11b... Master target 12... Support means 13... Moving means 14... Detection means 15... Machining means 21... Control unit 22... Storage unit 23... Input reception unit 24... Warning unit W... Workpiece

Claims

1. A machine tool for high-precision hole position machining controlled by a semi-closed loop, comprising: support means for supporting a table on which a workpiece to be drilled is placed; moving means for moving the support means via a conversion unit that converts the rotation of the shaft of a servo motor into linear movement; detection means for detecting position information of the center position of a master target provided on the table; processing means for performing a machining operation on the workpiece, and having: The master target is formed at a position corresponding to a hole position or a protrusion shape that is predetermined to be within an error of ±0.03 mm (Cp 1.33) in the machining hole positioning accuracy set for the workpiece. The workpiece has a plurality of machined portions. When the machining hole positioning accuracy of the machined portion of the workpiece is predetermined to be within the error of ±0.03 mm (Cp 1.33), the processing means calculates an error between the position information of the master target detected by the detection means and the position information of the machined portion of the workpiece corresponding to the position information of the master target, corrects the machining information of the workpiece using the calculated error, and drills the workpiece using the corrected machining information. A machine tool for high-precision hole position machining, characterized by the above.

2. The detection means calculates a correction value based on the temperature information of the master target, and corrects the position information of the master target with the correction value. The machine tool for high-precision hole position machining according to claim 1, characterized by the above.

3. A control method for a machine tool for high-precision hole position machining controlled by a semi-closed loop, comprising: support means for supporting a table on which a workpiece to be machined such as drilling is placed; moving means for moving the support means via a conversion unit that converts the rotation of the shaft of a servo motor into linear movement; detection means for detecting position information of the center position of a master target provided on the surface of the table; processing means for performing a machining operation on the workpiece; and a storage unit, wherein: The master target is formed at a position corresponding to a hole position or a protrusion shape that is predetermined to be within an error of ±0.03 mm (Cp 1.33) in the machining hole positioning accuracy set for the workpiece. The storage unit stores the position information of the machined portion of the workpiece and the machining information of the workpiece. The workpiece has a plurality of machined portions. The step in which the detection means detects the position information of the master target; The step in which the detection means detects the temperature information of the master target; The step in which the detection means calculates a temperature correction value using the temperature information of the master target, and corrects the position information of the master target using the temperature correction value to obtain the thermally corrected position information of the master target; When it is predetermined that the machining hole positioning accuracy of the machined portion of the workpiece is within an error of ±0.03 mm (C p 1.33), the machining means calculates the error between the thermally corrected position information of the master target acquired by the detection means and the position information of the machined portion of the workpiece corresponding to the position information of the master target, corrects the machining information of the workpiece stored in the storage unit based on the calculated error, and uses the thermally displaced corrected machining information of the workpiece obtained by the correction to machine the workpiece. A control method for a machine tool for high-precision hole position machining, characterized by comprising the steps of.

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