WO2017065054A1

WO2017065054A1 - Control device for machine tool

Info

Publication number: WO2017065054A1
Application number: PCT/JP2016/079459
Authority: WO
Inventors: 秀行藤原; 檜原　誠; 友揮山▲崎▼; 博幸森本; 忍平山
Original assignee: マツダ株式会社
Priority date: 2015-10-16
Filing date: 2016-10-04
Publication date: 2017-04-20
Also published as: CN108136558A; MX2018003446A; CN108136558B; JP6350481B2; JP2017074659A

Abstract

A control device for a machine tool (1) is provided with: a main shaft on which a drill (3) is installed; a casing (4) for rotatably supporting the main shaft; multiple stress sensors (70) for detecting the machining load on the drill (3); a control unit (100) for controlling the control amount for workpiece machining by the drill (3) on the basis of the detected load, which is the machining load calculated from the stress sensor (70) detection results; and multiple temperature sensors (71) for detecting the temperature of areas near the stress sensors (70) in the casing (4). The control unit (100) corrects the machining control amount on the basis of said detected load and the detection results of the temperature sensors (71).

Description

Machine tool controller

The present invention relates to a control device for a machine tool.

2. Description of the Related Art Conventionally, there has been known a machine tool including a stress detection device for detecting a machining load applied to a tool and a machining control device for controlling a control amount of machining by a tool based on a detection result by the stress detection device. It has been.

For example, the machine tool described in Patent Document 1 includes a torque detection device for detecting torque applied to a drill during machining instead of the stress detection device, and further detects a detected torque detected by the torque detection device. And a machining control device including a feed mechanism control device for controlling a feed mechanism for advancing the drill so that the feed speed is calculated by the feed speed calculation device. Is.

Japanese Patent Laid-Open No. 07-195256

By the way, when machining with the machine tool, the tool receives a reaction force from a workpiece as a machining target, and thus a load (machining load) is applied to the tool. In order to prevent breakage of the tool, it is necessary to control the control amount of machining of the workpiece by the machine tool so as not to apply a machining load of a certain value or more to the tool. However, if the control amount is set to a margin that is too large from the fixed value, the processing efficiency is lowered, so that the processing load is not applied to the tool without reducing the processing efficiency and the fixed value or more. It is desired to control the control amount, that is, the control amount that increases the processing efficiency while maintaining the processing quality of the tool.

The machine tool described in Patent Document 1 has a magnetostrictive torque sensor arranged around a drill as a torque detection device for detecting a machining load. The magnetostrictive torque sensor detects the torque applied to the tool from the change in the permeability of the rotating shaft of the tool. If a magnetostrictive torque sensor is placed around the drill, splashing of coolant from the tool will occur. Due to the influence of the above and the influence of the scattering of cutting waste, the change in the magnetic permeability of the rotating shaft cannot be detected accurately, and the torque applied to the tool during machining cannot be detected accurately. As a result, there is a possibility that the amount of machining control cannot be controlled appropriately only from the torque detected by the torque sensor. This can occur in the same manner even when the processing load is detected by the stress detection device.

Therefore, the stress detection device is arranged not on the periphery of the tool but on the support member that rotatably supports the spindle of the machine tool, and by separating the stress detection device from the processing position, the influence of the splash of coolant liquid from the tool or It is conceivable to avoid the influence of scattered chips. However, when the stress detection device is arranged on the support member in this way, the frictional heat of the tool at the time of machining or the heat of the coolant liquid heated by the frictional heat or the like causes the stress detection device in the support member near the support member or the support member. When the attached component is thermally deformed, the pressure acting on the stress detection device changes, and the stress detection device adds the stress based on the processing load applied to the tool to the stress detection device from the support member. The detected stress is also detected. That is, even if the stress detection device is arranged on the support member, the machining load applied to the tool during machining cannot be accurately detected. That is, only by changing the arrangement of the stress detection device, the control amount for processing the workpiece by the tool cannot be controlled to a control amount that increases the processing efficiency while maintaining the processing quality of the tool.

The present invention has been made in view of such a point, and an object of the present invention is to use a tool when a stress detection device is disposed in association with a support member that rotatably supports a spindle of a machine tool. An object of the present invention is to improve the processing efficiency while maintaining the processing quality.

Device for solving the problem

In order to solve the above-mentioned problems, in the present invention, for a control device of a machine tool, a spindle to which a tool for machining a workpiece is attached, a support member that rotatably supports the spindle, and a surrounding of the spindle A plurality of stress detection devices that are arranged in association with the support member and detect a processing load applied to the tool when the workpiece is processed, and detection of the processing load calculated from the detection result of the stress detection device Based on the load, a temperature of at least one of a machining control device that controls a control amount of machining of the workpiece by the tool, and a portion of the support member that is attached to the vicinity of the stress detection device and the vicinity of the stress detection device. A plurality of temperature detection devices to detect, the processing control device, the detection load calculated from the detection result of the stress detection device, and the temperature detection. Based on the detection temperature detected by the apparatus, it is configured to correct the control amount of the processing, and the things.

According to this configuration, the processing control amount is corrected based on the detection load calculated from the detection result of the stress detection device and the temperature of at least one of the supporting member in the vicinity of the stress detection device and the components attached to the vicinity. As a result, the control amount of the processing can be controlled to a control amount that increases the processing efficiency while maintaining the processing quality of the tool.

In other words, when a workpiece to be machined is machined with a tool, it is attached to the vicinity of the stress detection device in the support member or to the neighborhood by the frictional heat at the time of machining or the heat of the coolant liquid heated by the frictional heat. Even if the stress detection device detects the stress applied to the stress detection device from the support member, etc. in addition to the stress based on the processing load applied to the tool due to thermal deformation of the parts In addition to the detected stress detected by, based on the temperature of at least one of the vicinity of the stress detection device in the support member or the component attached to the vicinity detected by the temperature detection device, the control amount of processing (for example, The feed speed during machining, the number of rotations of the tool, etc.) are corrected. This makes it possible to control the amount of machining performed by the tool in consideration of the influence of thermal deformation of the support member and the like. As a result, it is possible to increase machining efficiency while maintaining the machining quality of the tool.

In one embodiment of the control device for the machine tool, the processing control device corrects the detection load calculated from the detection result of the stress detection device based on the detected temperature detected by the temperature detection device, Based on the detected load after correction, the control amount of the machining is corrected.

According to this configuration, even if the stress detection device detects the stress applied to the stress detection device due to thermal deformation of the support member or the like, the vicinity of the stress detection device in the support member detected by the temperature detection device The detection load calculated from the detection result of the detected stress of the stress detection device is corrected based on the temperature of at least one of the part or the part attached to the vicinity. Thereby, the influence of the stress detected by the thermal deformation of the support member or the like can be minimized, and the load based on the machining load applied to the tool can be detected with high accuracy. And since the control amount of a process can be correct | amended accurately based on the detection load after correction | amendment, process efficiency can be improved further, maintaining the process quality by a tool.

In the machine tool control apparatus, the support member has a cylindrical shape, and the support member includes a plurality of coolant oil passages extending in an axial direction of the support member at substantially equal intervals in a circumferential direction of the support member. Has been placed.

According to this configuration, the support member has a cylindrical shape, and the plurality of coolant oil passages are arranged at substantially equal intervals in the circumferential direction of the support member, so that the support member is caused by the heat of the coolant liquid flowing in each coolant oil passage. The temperature change in the circumferential direction becomes substantially uniform. As a result, the influence of the thermal deformation of the support member on the stress detection device is also substantially uniform in the circumferential direction of the support member, and the stress detected by the thermal deformation of the support member etc. acting on each stress detection device is also reduced. Since it is made substantially uniform, the calculation of the correction value for the detected load is simplified. As a result, it is possible to further improve the accuracy of detecting the processing load of the tool by the stress detection device.

In the control device for the machine tool, the tool is a drill, and the processing control device is configured to control the feed rate of the drill so that the detected load is within a preset target load range. It is desirable that

According to this configuration, the feed rate of the drill is controlled so that the detection load based on the machining load applied to the drill is within the preset target load range, so that an excessive load is not applied to the drill. The drill feed rate can be set to a relatively fast condition. Thereby, shortening of processing time can be aimed at, preventing damage to a drill.

In the machine tool control device, it is preferable that the stress detection device further includes a protective member that protects the processing tool from the machining waste generated by the processing of the workpiece.

That is, when machining scraps adhere to the stress detection device when machining a workpiece, the detection load increases or decreases only at the portion where the machining scraps adhere, and the machining load applied to the tool may not be accurately detected. There is. Therefore, by providing a protection member that protects the stress detection device from the processing waste, it is possible to prevent the processing waste from adhering to the stress detection device. Thereby, it can prevent that the detection accuracy of a stress detection apparatus falls by adhesion of processing waste etc.

As described above, according to the machine tool control device of the present invention, the support member includes a plurality of temperature detection devices that detect the temperature of at least one of the vicinity of the stress detection device or a component attached to the vicinity. The machining control device is configured to correct the machining control amount based on the detection load calculated from the detection result of the stress detection device and the detected temperature detected by the temperature detection device. In addition to the detection load calculated from the detection result by the stress detection device, based on the temperature of at least one of the support member detected by the temperature detection device in the vicinity of the stress detection device or a component attached to the vicinity, The control amount of machining can be corrected. Thereby, the control amount of processing can be controlled in consideration of the influence of thermal deformation of the support member and the like, and the processing efficiency can be increased while maintaining the processing quality of the tool.

It is the schematic which shows the machine tool controlled by the control apparatus which concerns on embodiment of this invention arrange | positioned in the machine room. It is sectional drawing which shows the outline of a machine tool. It is the figure which looked at the machine tool from the front. It is the disassembled perspective view which expanded the attachment part to the main-body part of a casing. It is a block diagram which shows the structure of the drive system and control system of a machine tool. It is a graph which shows the relationship between the detection load computed from the detection result of the stress sensor when performing 1st control, and the feed rate of a drill. It is a graph which shows the relationship between the detection load computed from the detection result of a stress sensor when performing 2nd control, and the feed rate of a drill. It is a graph which shows the relationship between the detection load calculated from the detection result of the stress sensor when performing 3rd control, and the feed rate of a drill. It is a graph which shows the relationship between the temperature change of the recessed part of a flange part when a workpiece | work is processed with a machine tool, and the detection load calculated from the detected stress detected with a stress sensor by the influence of this temperature change. FIG. 10 is a schematic diagram showing stress applied to the stress sensor in a time range of 0 to t1 in FIG. 9. FIG. 10 is a schematic diagram showing stress applied to the stress sensor in a time range from t1 to t2 in FIG. It is a flowchart which shows the processing operation at the time of operation of a machine tool by a control unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a machine tool 1 controlled by a control device according to an embodiment of the present invention disposed in a machine room. In the following description, for convenience of description, the axial direction of the main shaft 2 is referred to as the front-rear direction, the drill 3 side is referred to as the front side, and the counter-drill 3 side is referred to as the rear side.

The machine tool 1 is a horizontal machining center, and rotates a drill 3 as a tool attached to the front end portion of the spindle 2 together with the spindle 2 to process the workpiece W as a processing target. A housing 11 is disposed on the front side of the machine tool 1, and a processing chamber 12 closed by the housing 11 is formed in the housing 11. A part of the front side of the machine tool 1 is accommodated in the processing chamber 12 via a vertical wall 11 a on the rear side of the housing 11. The housing 11 is provided with a door (not shown) through which a user can enter and exit. Further, an automatic tool changer (not shown) for automatically changing a tool attached to the spindle 2 is arranged in the processing chamber 12.

In the processing chamber 12, a horizontally movable pallet 13 is disposed. The pallet 13 is connected to a feed shaft motor (not shown), and when the workpiece W is processed, the feed shaft motor is driven so that the pallet 13 (more precisely, the workpiece W on the pallet 13) is moved with respect to the drill 3. Sent. A jig 14 is installed on the pallet 13, and the workpiece W is chucked by the jig 14. The machine tool 1 performs boring or the like on the workpiece W with a drill 3 attached to the front end of the spindle 2. At this time, the vertical wall 11a plays a role of preventing cutting waste (processing waste) or the like from scattering from the processing chamber 12 to the stress sensor 70 described later. In this embodiment, the vertical wall 11a corresponds to a protective member. To do.

As shown in FIGS. 1 and 2, the machine tool 1 includes a main shaft 2, a drill 3 attached to a front end portion of the main shaft 2, and a casing 4 as a support member that rotatably supports the main shaft 2. And a main body 5 that supports the casing 4 including the main shaft 2.

The main shaft 2 is a substantially cylindrical member extending in the front-rear direction, and an axial rod 23 extending in the front-rear direction is inserted into the cylinder of the main shaft 2. The front end portion of the main shaft 2 is configured to protrude forward from the front end surface of the casing 4 in a state where the front end portion is disposed in the cylinder of the cylindrical casing 4. A chucking mechanism (not shown) including an axial rod 23 is formed at the front end portion of the main shaft 2, and the drill 3 is attached to the main shaft 2 by the chucking mechanism. A spindle motor 21 (see FIG. 5) for rotating the spindle 2 is disposed at the rear end of the spindle 2.

The casing 4 is a cylindrical member having a cylindrical shaft extending in the front-rear direction, and supports the main shaft 2 rotatably in the cylinder. A plurality of (four in FIG. 2) bearings 41 are arranged at positions closer to the front side on the inner wall side of the casing 4, and the main shaft 2 rotates within the cylinder of the casing 4 via the bearings 41. A rear end portion of the casing 4 is a flange portion 6 having a diameter larger than that of other portions of the casing 4.

Further, a coolant oil passage 42 through which a coolant liquid for cooling flows is disposed in the flange portion 6 of the casing 4 and the wall portion of the casing 4. Specifically, as shown in FIG. 2, the coolant oil passage 42 extends toward the radially inner side of the casing 4 on the rear side of the flange portion 6, and at a position corresponding to the wall portion of the casing 4 in the radial direction. After bending forward, it extends toward the front. When the workpiece W is machined, the coolant passes through the coolant oil passage 42 and is sprayed from the injection port provided at the front end of the casing 4 toward the drill 3 to cool the periphery of the workpiece W. The coolant oil passages 42 are arranged so as to be symmetrical with respect to the center of the casing 4 and at substantially equal intervals in the circumferential direction of the casing 4 so that the temperature distribution in the circumferential direction of the casing 4 is substantially uniform. It has become.

As shown in FIGS. 2 and 3, the casing 4 is attached and fixed to the main body 5 by the preload bolts 44 at a plurality of locations (6 in the present embodiment) of the flange portion 6. It is supported. Specifically, as shown in FIG. 4, the main body 5 is formed with a main body side bolt hole 5a, and the flange 6 is formed with a flange side bolt hole 6a at a position corresponding to the main body side bolt hole 5a. Then, the end portions of the shaft portion 44a of the preload bolt 44 are inserted into the bolt holes 5a and 6a, respectively. A nut 44c is fastened from the front side of the flange portion 6 to the front end portion of the shaft portion 44a, whereby the casing 4 is fastened to the main body portion 5. At this time, as shown in FIG. 3, a plurality of fastening locations by the preload bolt 44 are provided at equal intervals in the circumferential direction (six locations in this embodiment), and the flange portion 6 is attached to the main body by the preload bolt 44 at each fastening location. The casing 4 is supported by the main body 5 by being fastened to the part 5.

As shown in FIGS. 2 and 4, a part of the flange portion 6 near the rear side where the preload bolt 44 is attached is recessed in a substantially rectangular shape from the outer peripheral surface of the flange portion 6 toward the radially inner side. It is part 6b. The recessed portions 6b are formed at a plurality of locations (six locations in the present embodiment) so as to be substantially equidistant in the circumferential direction of the flange portion 6. The remaining portion on the front side at the position where the recessed portion 6b of the flange portion 6 is formed is a wall. As shown in FIGS. 2 and 4, the flange side bolt hole 6a is formed in the wall portion, and When the preload bolt 44 is inserted into the main body portion side and the flange

side bolt holes

5a, 6a, the shaft portion 44a is positioned in the recessed portion 6b.

As shown in FIG. 2 and FIG. 4, one stress sensor 70 as a stress detection device is fitted into each shaft 44a of each preload bolt 44 (that is, six in total). Each stress sensor 70 is disposed in each recessed portion 6b of the flange portion 6 while being supported by the shaft portion 44a of each preload bolt 44, and is substantially in the circumferential direction of the casing 4 as shown in FIG. It arrange | positions so that it may become equal intervals. As will be described in detail later, the processing load applied to the drill 3 when the workpiece W is processed is calculated by the stress sensor 70 detecting the stress applied by the force transmitted to the casing 4 via the bearing 41. Is done.

Further, as shown in FIGS. 2 and 3, in the vicinity of each stress sensor 70 in the casing 4, that is, in each recessed portion 6 b in the flange portion 6 of the casing 4, temperature detection for detecting the temperature of each recessed portion 6 b. A temperature sensor 71 as an apparatus is attached. In the present embodiment, the temperature sensor 71 is attached to each of the recessed portions 6b and detects the temperature of each of the recessed portions 6b. However, the temperature sensor 71 is connected to each recessed portion that is the vicinity. The temperature of each preload bolt 44 may be detected by attaching to each preload bolt 44 arranged in the portion 6a. Further, the temperature sensors 71 may be attached to all the stress sensors 70, the recessed portions 6b, and the preload bolts 44.

Specifically, when the casing 4 is attached to the main body 5, as shown in FIG. 4, the collar 51 in which the collar side bolt hole 51 a is formed between the flange 6 and the main body 5 is connected to the collar side. The bolt holes 51a are aligned and positioned so as to correspond to the main body side bolt holes 5a. Next, the rear end portion of the shaft 44a of the preload bolt 44 in which the stress sensor 70 is fitted in advance is inserted into the main body side bolt hole 5a through the collar side bolt hole 51a. Next, the casing 4 is aligned so that the flange-side bolt hole 6a corresponds to the front end of the shaft portion 44a of the preload bolt 44 inserted into the main body-side bolt hole 5a. The casing 4 is moved so that the front end portion of the shaft portion 44a is inserted into the flange side bolt hole 6a, and the front end portion of the shaft portion 44a is projected from the flange side bolt hole 6a toward the front side. And the nut 44c is fastened to the part which protruded from the flange side bolt hole 6a in the front side edge part of the axial part 44a via the washer 44b. Thereby, the casing 4 is attached to the main body 5. The temperature sensor 71 is attached to the recessed portion 6 b in the middle of attaching the casing 4 to the main body portion 5.

In this embodiment, the stress sensor 70 is obtained by processing a known quartz piezoelectric element into a ring shape, and detects a stress acting on the quartz piezoelectric element from a change in charge of the quartz piezoelectric element. When machining the workpiece W by the drill 3, the force (the thrust force in the main shaft direction and the bending stress acting on the casing 4, etc.) transmitted from the drill 3 to the casing 4 through the main shaft 2 and the bearing 41. ) To detect the stress acting on the quartz piezoelectric element and input the detected stress to the control unit 100 described later, whereby the processing load applied to the drill 3 is calculated by the control unit 100. The processing load refers to, for example, torque, bending stress, and the like.

The temperature sensor 71 is a thermocouple in this embodiment. Each temperature sensor 71 detects the temperature of each recess 6b, and outputs the detected temperature to the control unit 100 described later.

FIG. 5 is a block diagram showing the configuration of the drive system and the control system of the machine tool 1.

In the present embodiment, based on the detected stress detected by the stress sensor 70 and the detected temperature detected by the temperature sensor 71, the control unit 100 calculates the machining load applied to the drill 3 when machining the workpiece W. Then, the control amount (for example, the feed speed of the drill 3) of the work W processed by the drill 3 is controlled to a condition corresponding to the processing load. In the present embodiment, the control unit 100 corresponds to a machining control device.

The control unit 100 is a controller based on a well-known microcomputer, and includes a central processing unit (CPU) that executes a program, a memory that is configured by, for example, a RAM or ROM, and stores a program and data, and an electrical signal And an input / output (I / O) bus.

The stress sensor 70 inputs an electrical signal representing the detected stress to the control unit 100. Specifically, an electrical signal representing the detected stress is input from the stress sensor 70 to the amplifier 81, amplified by the amplifier 81, converted into a digital signal by the AD converter 82, and input to the control unit 100. Is done.

The electrical signal representing the detected temperature detected by the temperature sensor 71 is converted into a digital signal by the AD converter 83 and then input to the control unit 100.

The control unit 100 calculates a processing load applied to the drill 3 at the time of processing the workpiece W based on the electrical signal regarding the detected stress and the detected temperature, and based on the calculation result, the processing of the workpiece W by the drill 3 is calculated. A control amount is determined, and a drive signal based on the control amount of the machining is transmitted to the spindle motor 21 via the amplifier 84 and is also transmitted to the feed shaft motor of the pallet 13 so that the workpiece W is transferred to the drill 3. The feed speed is controlled as a control amount for machining the drill 3 by moving the drill 3.

Next, the control executed by the control unit 100 will be described with reference to FIGS. In the following description, the machining load calculated from the stress detected by the stress sensor 70 is referred to as a detected load.

FIG. 6 shows the first control which is an example of the control executed by the control unit 100. The first control is executed mainly when long-time machining is performed, such as when a relatively long hole is opened.

In the first control, a detected load (more precisely, a corrected detected load described later) calculated from the detected stress detected by each stress sensor 70 at the time of machining by the drill 3 is a preset target load. In this control, the feed rate of the drill 3 is changed at any time so as to be within the range. The target load is set to have a certain range rather than a specific value, as shown by a broken line in FIG. 6, and is set to the most efficient range in which the machining quality by the drill 3 can be maintained. The The target load may be set within a certain range or may be set within a different range for each tool. In addition, every time the user uses the machine tool 1, the target load is set to an arbitrary range. It may be.

Referring to FIG. 6, the control unit 100 first drives the spindle motor 21 and also drives the feed shaft motor of the pallet 13 while increasing the feed speed of the drill 3 as shown by a thin line in FIG. The workpiece W is controlled to be processed. At this time, the feed speed of the drill 3 increases, and the machining load applied to the drill 3 from the workpiece W increases, so that the detection load calculated by the control unit 100 also increases as shown by the thick line in FIG. When the detected load falls within the target load range, the control unit 100 fixes the feed speed of the drill 3 to the feed speed when the detected load falls within the target load range, and continues processing.

After that, for example, if processing waste accumulates in the hole processed by the drill 3, the processing load applied to the drill 3 increases, and thus the detection load increases. When the detected load exceeds the target load, the control unit 100 changes the feed speed of the drill 3 to gradually decrease (decrease by a preset speed) until the detected load falls within the target load range. . When the detected load falls within the target load range, the control unit 100 continues the machining by fixing the feed speed of the drill 3 to the feed speed when the detected load falls within the target load range.

Thereafter, for example, when the detected load falls below the target load by the above-described gradual reduction control, the control unit 100 gradually increases the feed speed of the drill 3 (increases by a preset speed) until the detected load falls within the target load range. To change). When the detected load falls within the range of the target load, the control unit 100 continues the machining by fixing the feed rate of the drill 3 to the feed rate when the detected load falls within the range of the target load. Hereinafter, the processing load of the drill 3 is controlled within the range of the target load by this repetition. It should be noted that the user may be able to arbitrarily set the rate of decrease during gradual decrease and the rate of increase during gradual increase.

According to this first control, the maximum feed speed at which the machining load applied to the drill 3 is within the target load range while the machining load applied to the drill 3 is controlled within the target load range when the workpiece W is machined. Since the workpiece W can be machined, the machining time of the workpiece W can be shortened while maintaining the machining quality of the drill 3.

FIG. 7 shows the second control which is an example of the control executed by the control unit 100. The second control is a control that is mainly executed when short-time machining is performed a plurality of times, such as when a plurality of relatively short holes are formed.

In the second control, the average detected load is determined from the average value (hereinafter, referred to as average detected load) of the detected load calculated by the control unit 100 at the time of the previous machining (more precisely, the corrected detected load described later). A drill feed rate correction value for making it within the load range is calculated, and at the next machining, control is performed so that machining is performed at the feed rate corrected with the feed rate correction value.

FIG. 7 shows a case where two holes are opened by the drill 3 as an example. Referring to FIG. 7, the control unit 100 first drives the spindle motor 21 to open the first hole and also drives the feed shaft motor of the pallet 13 to drill the drill as shown by a thin line in FIG. After the feed speed of 3 is increased to a predetermined speed, control is performed so that machining is performed at a constant feed speed until the end of machining. At this time, the control unit 100 calculates the processing load applied to the drill 3 from the detected stress detected by the stress sensor 70 as shown by a thick line in FIG. 7, and calculates the average as shown by a one-dot chain line in FIG. Calculate the detection load.

For example, as shown in FIG. 7, when the calculated average detected load is lower than the target load, the control unit 100 sets a feed speed correction value for making the average detected load within the target load range. When the second hole is calculated and calculated, as shown in FIG. 7, the feed rate of the drill 3 is corrected with the feed rate correction value, and the feed rate is increased to perform machining. Control. Thereby, as shown in FIG. 7, the average detected load when the second hole is opened is within the range of the target load.

Even after the second hole is opened, when the machining is performed at the corrected feed rate (for example, when the third hole is opened), the average detected load exceeds the target load, or the average is reversed. When the detected load falls below the target load again, the feed speed correction value for making the average detected load within the target load range is calculated again, and the next machining is performed (for example, the fourth hole is opened). Control) to perform machining at the feed speed corrected with the feed speed correction value. Hereinafter, the processing load of the drill 3 is controlled within the range of the target load by this repetition.

Even in the second control, the machining load applied to the drill 3 during the machining of the workpiece W is controlled within the target load range, and the highest feed speed at which the machining load applied to the drill 3 is within the target load range. Since the workpiece W can be machined, the machining time of the workpiece W can be shortened while maintaining the machining quality of the drill 3. In the description of the second control described above, the average detection load is calculated for each machining and the feed speed at the next machining is corrected. However, the predetermined control is performed every two or more machining operations. The average detected load of machining for the number of times is calculated, the feed speed correction value corresponding to the average detected load is calculated, and the next predetermined number of times of machining is performed at the feed speed corrected with the feed speed correction value. It may be.

FIG. 8 shows the third control which is an example of the control executed by the control unit 100. The third control is a control executed to prevent the tool from being damaged.

In the third control, when the workpiece W is machined by the drill 3, when the detected load calculated by the control unit 100 (more precisely, the corrected detected load described later) reaches a predetermined upper limit load, 3 is a control for stopping the processing by 3. The upper limit load is a load that is higher than the target load and does not damage the tool such as the drill 3. The upper limit load may be set to a constant value or a different value for each tool, and is set to an arbitrary value every time the user uses the machine tool 1. It may be.

Referring to FIG. 8, the control unit 100 first executes the first control and the second control to drive the spindle motor 21 and the feed shaft motor of the pallet 13. As shown, the feed speed of the drill 3 is increased until the detected load reaches the target load range, and after reaching the target load, the feed speed of the drill 3 is fixed to the feed speed at the time of arrival. Take control.

When the workpiece W is processed at the above feed speed, for example, cutting waste accumulates in the hole processed by the drill 3, and an excessive load is applied to the drill 3, and the detection load is increased. When the upper limit load indicated by the two-dot chain line in FIG. 8 is reached, the control unit 100 determines that the drill 3 may be damaged, and stops driving the spindle motor 21 and the feed shaft motor of the pared 13. Then, the machining by the drill 3 is stopped.

According to the third control, the machining by the drill 3 is stopped when an excessive load is applied to the drill 3 while shortening the machining time of the workpiece W by the first control and the second control. Breakage of the drill 3 can be prevented.

Here, in particular, in the casing 4 and the main body 5, the portion of the coolant oil passage 42 through which the coolant liquid flows is disposed so that the heat of the coolant liquid heated by the frictional heat of the drill 3 is easily transmitted. Deformable due to the heat of the liquid. When the casing 4 or the main body 5 is thermally deformed, the stress sensor 70 disposed in the recessed portion 6b of the flange 6 is moved from the main body 5 or the flange 6 of the casing 4 and further from the preload bolt 44 that supports the stress sensor 70. Since the stress is received and the stress sensor 70 detects stress other than the stress based on the processing load of the drill 3, the detection accuracy by the stress sensor 70 is lowered.

The effect of this heat will be described in detail with reference to FIGS.

9, the upper graph in FIG. 9 is a graph showing the temperature change of the recessed portion 6b in the flange portion 6 with respect to time, and the lower graph in FIG. 9 is a graph showing the change in detection load with respect to time. . In the upper and lower graphs, the horizontal axis is an axis indicating time, and is set to 0 immediately before the workpiece W is processed. The graph of the temperature change is the temperature change of the recessed portion 6b calculated based on the temperature detected by the temperature sensor 71, and the temperature change when the temperature of the recessed portion 6b immediately before processing the workpiece W is set to 0. It is. The detected load graph shows the detected load when no machining load is applied to the drill 3. In the graph of the detected load, the solid line is a detected load calculated based on the detected stress actually detected by each stress sensor 70, and the broken line is a reproduction of a change in the actually detected load by simulation. The chain line is obtained by correcting the actually measured load, which will be described later.

Referring to FIG. 9, the temperature of the recess 6a rises in the time range from 0 to t1 and in the range from t1 to t2 (> t1), and becomes substantially constant in the time range of t2 or more. At this time, the detected load calculated from the actual detected stress increases from 0 in the time range from 0 to t1, and decreases from 0 in the time range from t1 to t2 (> t1). In a range where the time is t2 or more, a constant value is maintained with a value smaller than 0.

The stress acting on the stress sensor 70 in the process of changing the detected load will be specifically described. In the time range from 0 to t1, as shown in FIG. 10, the main body part 5 and the flange part 6 are thermally deformed by the heat of the coolant, so that the stress sensor 70 sandwiched between them is It is pressed by the flange portion 6. Thereby, since the stress sensor 70 receives compressive stress, the detection load calculated from the detection stress at this time rises from 0 as shown in the range from 0 to t1 in FIG. In the time range from t1 to t2 (> t1), the heat of the coolant is transmitted to the preload bolt 44, and the preload bolt 44 is deformed by the influence of heat. At this time, the axial force (preload force) in the front-rear direction is reduced by the preload bolt 44 in the stress sensor 70 as shown in FIG. Thereby, as shown in the range from t1 to t2 in FIG. 9, the detected load calculated from the detected stress at this time decreases. When the time is in the range of t2 or more, since the temperature is substantially constant, the stress received by the stress sensor 70 from the preload bolt 44 is also constant. Therefore, the detected load calculated from the detected stress at this time is a value smaller than zero. It remains almost constant.

As described above, the stress sensor 70 detects stresses other than the stress based on the processing load of the drill 3 by thermal deformation of parts such as the preload bolt 44 attached to the casing 4 in the vicinity of the stress sensor 70 in the flange portion 6. As a result, the actual machining load applied to the drill 3 when machining the workpiece W cannot be accurately calculated. As a result, in the correction based only on each detected load based on the detected stress detected by each stress sensor 70, the control amount of processing cannot be accurately corrected, and the control amount of processing of the workpiece W by the drill 3 is It becomes impossible to control to an appropriate control amount that increases the processing efficiency while maintaining the processing quality of the drill 3.

Therefore, in the present embodiment, the temperature of each recess 6 b in the flange portion 6 of the casing 4 is detected by each temperature sensor 71, and each detected load based on the detected stress detected by each stress sensor 70 and the temperature sensor 71 are used. The processing control amount is corrected based on the detected temperature detected.

Specifically, the control unit 100 corrects each detected load based on the detected stress detected by each stress sensor 70 in accordance with the detected temperature detected by the temperature sensor 71, so that each stress sensor in the flange portion 6 is corrected. The influence of thermal deformation of the vicinity of 70 and the preload bolt 44 is removed, and the control amount of machining is corrected based on the detected load after correction.

The details of the correction will be described. A graph representing the actual detection load shown by the broken line in the lower graph of FIG. 9 is calculated in advance by simulation or the like, and this is used as a change in the detection load with respect to a temperature change. The corrected one is stored in advance in the control unit 100 as a detection load correction calculation formula or a detection load correction map. Then, when machining the workpiece W with the drill 3, the correction value of the detected load corresponding to each detected temperature is calculated or read from the detected load correction calculation formula or the detected load correction map, and each correction value is calculated. Use to correct each detected load. By performing this correction, the zero point of the detected load is corrected as indicated by the one-dot chain line in the graph of the detected load in FIG. Can be reduced. The range from time 0 to t1 in the load line reproduced by simulation in the lower graph of FIG. 9 is not visible because it overlaps with the actually detected load line, but is reproduced by simulation. The load line shows a change rising from 0 in the range from 0 to t1 as in the case of the actually detected load.

It should be noted that the correction value for the temperature change not set in the detected load correction map may be calculated by interpolation or extrapolation from the correction value set in the detected load correction map.

At this time, since the temperature change differs for each position where each stress sensor 70 is arranged, the control unit 100 calculates a correction value for each detected load based on the detected stress detected by each stress sensor 70, and Each detected load is corrected by the correction value.

Next, the control operation of the control amount of machining of the machine tool 1 by the control unit 100 will be described according to the flowchart of FIG. The flowchart of FIG. 12 is a flowchart when the detected load is corrected using the detected load correction map, and the following description is the control operation of the control unit 100 when the detected load correction map is used. Moreover, the control amount of a process is made into the feed rate of the drill 3 as an example.

First, in step S1, the detection load before correction is calculated from the stress detected by each stress sensor 70 as data necessary for calculating the detection load based only on the machining load actually applied to the drill 3, and the flange The temperature of each recessed part 6b in the part 6 is detected.

Subsequently, in step S2, the detected load correction map stored in advance in the controller 100 is read, and the correction value for each detected load before correction corresponding to each detected temperature is read.

In the next step S3, each detected load before correction is corrected by each correction value read in step S2. As a result, the zero point of the detected load is corrected, and each corrected detected load represents a detected load based only on the machining load actually applied to the drill 3.

In the next step S4, it is determined whether or not the detected load corrected in step S3 is equal to or higher than the upper limit load. When the determination in step S4 is YES, the process proceeds to step S5, the control unit 100 determines that the drill 3 may be damaged, executes the above-described third control, and stops the machining by the drill 3 And then return. On the other hand, when the determination in step S4 is NO, the process proceeds to step S6.

In step S6, it is determined whether or not the corrected detected load is within the target load range. When the determination in step S6 is YES, the machining is continued at the current feed speed, and then the process returns. On the other hand, when the determination in step S6 is NO, the process proceeds to step S7.

In the next step S7, the feed rate of the drill 3 is changed. For example, when the control unit 100 is executing the first control described above, when the corrected detected load exceeds the target load, the feed rate of the drill 3 is gradually decreased, while the corrected detected load is reduced to the target load. When it is lower, the feed rate of the drill 3 is gradually increased. Further, for example, when the control unit 100 is executing the second control, a feed speed correction value for making the average detected load within the target load range is calculated from the average detected load at the previous machining. Then, the feed rate of the drill 3 is corrected by the feed rate correction value. After step S7, the process returns thereafter.

The control unit 100 controls the feed rate of the drill 3 according to the above flow every predetermined time (for example, 8 milliseconds). Thereby, the processing time can be shortened while maintaining the processing quality of the drill 3. When correcting the detected load using the detected load correction calculation formula, in step S2, the detected load correction calculation formula is read out, and a correction value for the detected load is calculated based on the calculated formula. In step S3, the detected load before correction is corrected based on the calculated correction value.

Therefore, the control device of the machine tool 1 according to the present embodiment includes a plurality of temperature sensors 71 that detect the temperature of the recessed portion 6 b in the flange portion 6 of the casing 4, and the control unit 100 is detected by the stress sensor 70. Since the processing control amount is corrected based on the detected load calculated from the detected stress and the detected temperature detected by the temperature sensor 71, the detection is performed based on the detected temperature of the recessed portion 6b. Each detected load calculated from the detected stress detected by each stress sensor 70 is corrected so as to minimize the influence of stress due to thermal deformation of the flange 6 etc. of the load, and the heat of the flange 6 etc. is corrected. The influence due to the deformation can be minimized, and the load based on the machining load of the drill 3 can be detected with high accuracy. And based on the detection load after correction | amendment, the control amount of a process can be correct | amended accurately. As a result, when the stress sensor 70 is disposed in the casing 4, it is possible to increase the processing efficiency while maintaining the processing quality of the tool.

The present invention is not limited to the above embodiment, and can be substituted without departing from the spirit of the claims.

For example, in the above embodiment, based on the detected temperature detected by the temperature sensor 71, the zero point of the detected load calculated from the detected stress detected by the stress sensor 70 is corrected, and based on each detected load after correction. The control amount of machining by the drill 3 is controlled, but not limited to this, the control amount of machining by the drill 3 is based on the detected temperature detected by the temperature sensor 71 and the detected load before correction. You may comprise so that it may correct | amend. In this case, for example, from the detected temperature and the detected load before correction, a calculation formula for calculating the correction amount for the processing control amount and a map for reading the correction amount are stored in the control unit 100, and A correction amount may be calculated or read out from a calculation formula or a map to correct the machining control amount.

In the above embodiment, the tool is the drill 3, but is not limited thereto, and may be a milling machine or a reamer. In this case, the control amount of the processing controlled by the control unit 100 is the rotational speed and moving speed of the tool.

Moreover, in the said embodiment, although the feed shaft motor of the pallet 13 is drive-controlled and the feed speed of a tool is controlled, it is not restricted to this, The feed speed of the tool by moving the main-body part 5 provided with the main shaft 2 May be controlled.

Furthermore, in the said embodiment, although the casing 4 is made into the cylindrical shape, not only this but a square tube shape may be sufficient.

Moreover, in the said embodiment, although the stress sensor 70 is arrange | positioned in the recessed part 6b of the flange part 6 which is an attachment part to the main-body part 5 in the casing 4, it is not restricted to this, From the vertical wall 11a of the housing 11 As long as the position is on the rear side, the casing 4 may be disposed at a position on the front side of the attachment position to the main body 5. For example, the casing is divided into two in the axial direction of the main shaft 2. You may make it arrange | position a stress sensor to an attachment flange part.

The above-described embodiment is merely an example, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

The present invention is useful for a machine tool having a stress detection device for detecting a machining load applied to a tool during machining of a workpiece.

1 Machine tool 2 Spindle 3 Drill (tool)
4 Casing (support member)
6a Concave part (near part of stress detection device in support member)
11a Vertical wall (protective member)
42 Coolant oil passage 44 Preload bolt (parts installed in the vicinity)
70 Stress sensor (stress detector)
71 Temperature sensor (temperature detector)
100 Control unit (processing control device)

Claims

A machine tool control device,
A spindle to which a tool for machining a workpiece is attached;
A support member that rotatably supports the main shaft;
A plurality of stress detection devices arranged to be associated with the support member so as to surround the spindle, and for detecting a machining load applied to the tool during machining of the workpiece;
A machining control device that controls a control amount of machining of the workpiece by the tool based on a detection load that is the machining load calculated from a detection result of the stress detection device;
A plurality of temperature detection devices for detecting the temperature of at least one of the vicinity of the stress detection device in the support member and the components attached to the vicinity;
The processing control device is configured to correct the control amount of the processing based on a detection load calculated from a detection result of the stress detection device and a detected temperature detected by the temperature detection device. A machine tool control device characterized by the above.
In the machine tool control device according to claim 1,
The processing control device corrects the detection load calculated from the detection result of the stress detection device based on the detected temperature detected by the temperature detection device, and performs the processing based on the corrected detection load. A machine tool control device configured to correct a control amount.
In the machine tool control device according to claim 1 or 2,
The support member has a cylindrical shape,
A control device for a machine tool, wherein a plurality of coolant oil passages extending in an axial direction of the support member are arranged in the support member at substantially equal intervals in a circumferential direction of the support member.
In the machine tool control device according to claim 1 or 2,
The above tool is a drill,
The machining control device is configured to control a feed rate of the drill that is a control amount of the machining so that the detected load falls within a preset target load range. Machine tool controller.
In the machine tool control device according to claim 1 or 2,
A machine tool control device, further comprising: a protective member that protects the stress detection device from machining waste generated by machining the workpiece by the tool.
The machine tool control device according to claim 3,
The above tool is a drill,
The machining control device is configured to control a feed rate of the drill that is a control amount of the machining so that the detected load falls within a preset target load range. Machine tool controller.
The machine tool control device according to claim 6,
A machine tool control device, further comprising: a protective member that protects the stress detection device from machining waste generated by machining the workpiece by the tool.
The machine tool control device according to claim 4,
A machine tool control device, further comprising: a protective member that protects the stress detection device from machining waste generated by machining the workpiece by the tool.