Machine tool

Abstract

To provide a machine tool configured so that amounts of lubricants and flow volumes of air which are fed to a bearing part can be adjusted in consideration of not only rotation speed of a main spindle of a main spindle device but also of loads on the bearing during cutting processing.SOLUTION: When a control part 31 operates a main spindle device 100 in accordance with an NC program 34 stored in a storing part 33, a calculating part 32 performs simulation of rotation speed of a main spindle and of cutting loads, from the selected NC program 34, and segments simulated results in accordance with an operation condition recorded in the storing part 33. The control part 31 operates the main spindle device 100 in accordance with the NC program 34, and at the same time adjusts quantities of lubricants and flow volumes of air, by comparing quantities of lubricants and flow volume of air which are required for an operation condition preliminarily recorded in the storing part 33 with the simulated results.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a machine tool having a rotary tool spindle device (hereinafter simply referred to as the spindle device) of a machine tool, a lubrication device that supplies lubricating oil and air to a bearing portion of a spindle of the spindle device, and an operation control unit that controls the spindle device and the lubrication device. [Background technology]

[0002] Grease lubrication, oil mist lubrication, oil air lubrication, etc. are used as lubrication methods for the bearing part of the spindle of the spindle device of a machine tool. All of these methods aim to obtain smooth movement of the spindle device by forming a thin lubricating oil film on the bearing part using lubricating oil to reduce friction between the parts that make up the bearing part and reduce wear by preventing direct contact between the parts. Grease lubrication is maintenance-free, such as not requiring replenishment of lubricating oil, but is not suitable for high speed and long life. In contrast, oil mist lubrication and oil air lubrication are methods in which mist or oil droplet-like lubricating oil is supplied to the bearing part using clean air as power, and since it requires the supply of lubricating oil and air, regular maintenance such as oiling and filter element replacement is required, but compared to grease lubrication, it allows for high speed and long life.

[0003] Conventionally, there is a machine tool having a lubrication device that adopts an oil-air lubrication method characterized by changing the amount of lubricating oil according to the spindle rotation speed. Patent Document 1 describes a machine tool that aims to provide stable lubrication performance from low speed operation to high speed operation by changing the amount of lubricating oil supplied to the bearing part according to the rotation speed while the spindle of the spindle device is rotating. Patent Document 2 describes a machine tool that adds a coefficient according to the rotation speed of the spindle for each unit time, supplies lubricating oil and resets the integrated value when the integrated value exceeds a specified value, and changes the supply interval according to the rotation speed and its operating time by setting the coefficient small in the low speed range and large in the high speed range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-76783 A [Patent Document 2] Japanese Patent Application Publication No. 6-33942 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, the operation pattern of the spindle device varies depending on the user's industry and usage. For example, machines that make up a manufacturing line are expected to always repeat a certain process, and machines that perform everything from rough processing to finishing are expected to be used under a wide range of operating conditions, including low to high speed rotation. In addition, users who perform processing with a large amount of machining allowance, such as cutting aluminum alloy bulk materials, such as in aircraft and semiconductor-related work, are expected to operate for long periods of time at relatively high speeds. In addition, in cases where tools are changed frequently per workpiece, the spindle will stop and rotate intermittently.

[0006] The thickness of the lubricant film formed in the bearing by the supply of lubricant varies depending on the viscosity of the lubricant, the rotational speed, and the load (stress) received by the bearing. However, both of the above conventional machine tools change the amount of lubricant supplied in consideration of changes in the rotational speed of the main spindle, but do not take into account external loads such as cutting forces. For example, in a situation where high-load cutting continues for a long period of time at low rotation speed, the lubricant film thickness decreases, which may lead to damage to the rolling contact part of the bearing.

[0007] There is also concern that the spindle may be damaged due to usage methods or conditions that the machine manufacturer did not anticipate, resulting in machine downtime. For example, when operating a machine after a long period of inactivity, the manufacturer advises that a break-in should be performed to stabilize the supply of lubricating oil to the spindle bearings. However, when this is merely a warning rather than mandatory, there is a problem that this is not always followed.

[0008] Therefore, an object of the present invention is to provide a machine tool that can adjust the amount of lubricating oil and air flow to the bearing section, taking into consideration not only the rotational speed of the spindle of the spindle device but also the load on the bearing section during cutting processing. [Means for solving the problem]

[0009] In order to achieve the above object, the invention described in claim 1 has a spindle unit that rotates a tool attached to a spindle to perform cutting processing, a lubrication unit that supplies lubricating oil and air to a bearing part of the spindle, and an operation control unit that controls the operation of the spindle unit and the lubrication unit, and the operation control unit includes a control unit that operates the spindle unit and the lubrication unit, a calculation unit that performs various calculations, and a memory unit in which an operation program for the spindle unit including at least a spindle speed command and a cutting feed command is stored, in addition to the operation program, and the memory unit pre-records operating conditions corresponding to the spindle speed of the spindle and the cutting load on the bearing part during cutting processing, and the amount of lubricating oil and air flow rate by the lubrication unit required for the operating conditions, and the calculation unit classifies the operating program from the rotation speed command and the cutting feed command in the operating program, and the control unit operates the spindle unit in accordance with the operating program, and adjusts the amount of lubricating oil and the air flow rate by the lubrication unit by comparing the result of the classification with the amount of lubricating oil and the air flow rate required for the operating conditions recorded in the memory unit.

[0010] In addition, the invention described in claim 2 is characterized in that, in the invention described in claim 1, the classification of the operating program is performed based on the results of the simulation by the calculation unit simulating the spindle rotation speed and cutting load according to the operating program. The invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2, the memory unit stores a plurality of operating programs in accordance with the workpiece to be machined, and the control unit operates the spindle device according to an operating program selected from the plurality of operating programs. The invention described in claim 4 is characterized in that, in the invention described in claim 1 or 2, when the control unit operates the spindle device according to the operating program and changes the spindle rotation speed, it changes the amount of lubricating oil and / or the air flow rate by the lubrication device going back a predetermined time. The invention described in claim 5 is characterized in that, in the invention described in claim 1 or 2, when the spindle device is stopped for a time period equal to or longer than a predetermined threshold value, the control unit gradually increases the spindle rotation speed and then causes the spindle device to perform an operation according to the operating program. Effect of the Invention

[0011] According to the present invention, the cutting tool has a spindle device that rotates a spindle to perform cutting, a lubrication device that supplies lubricating oil and air to the bearing of the spindle device, and an operation control unit that controls the operation of the spindle device and the lubrication device. The memory unit of the operation control unit stores in advance the operation conditions according to the combination of the respective values ​​of the spindle speed and the cutting load, and the amount of lubricating oil and the air flow rate required for the operation conditions. When the control unit of the operation control unit operates the spindle device according to the operation program stored in the memory unit, the calculation unit of the operation control unit performs a simulation of the spindle speed and the cutting load from the operation program, classifies the simulation results according to the operation conditions recorded in the memory unit, and records them in the memory unit. Then, the control unit operates the spindle device according to the operation program, and at the same time, compares the amount of lubricating oil and the air flow rate required for the operation conditions recorded in the memory unit with the simulation results classified by the calculation unit based on the operation conditions recorded in the memory unit, and adjusts the amount of lubricating oil and the air flow rate supplied to the bearing of the spindle device by the lubrication device. Therefore, by adjusting the amount of lubricating oil and air supplied, taking into consideration not only the rotation speed of the spindle but also the load on the bearing during cutting, it is possible to prevent damage to parts such as the bearing. [Brief description of the drawings]

[0012] [Figure 1]FIG. 2 is a schematic diagram showing a spindle device, a lubrication device, and an operation control unit. [Diagram 2] 1 is a table showing the amount of lubricating oil and the air flow rate for each operating condition. [Diagram 3] 13 is a graph in which the results of the simulation by the calculation unit are divided according to the operating conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An example of a machine tool according to an embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic diagram showing a spindle unit 100, a lubrication unit 200, and an operation control unit 300 according to the machine tool of the present invention. The main components of the spindle unit 100 include a spindle 1 and a bearing unit 2 that rotatably supports the spindle 1. The bearing unit 2 includes front bearings 3a, 3a, a rear bearing 3b, a bearing inner ring spacer 4, a bearing outer ring spacer 5, a front bearing outer ring holder 6, a front bearing housing 7, front bearing lubrication nozzles 8, 8, a front bearing inner ring holder 9, a rear bearing lubrication nozzle 10, a rear bearing housing 11, a rear bearing outer ring holder 12, and a rear bearing inner ring holder 13. The spindle unit 100 also includes a motor stator 14a and a rotor 14b that rotate the spindle 1, and a tachometer 15 that detects the rotational speed of the spindle 1. The spindle unit 100 rotates a tool (not shown) attached to the spindle 1 to perform cutting.

[0014] The front bearings 3a, 3a and the rear bearing 3b are interference-fitted onto the main shaft 1 and fixed to prevent slipping relative to each other. A combined bearing is used for the front bearings 3a, 3a, and an inner ring spacer 4 and an outer ring spacer 5 are provided between the front bearings 3a, 3a to apply an appropriate preload between them. The front bearings 3a, 3a and the inner ring spacer 4, which are interference-fitted onto the main shaft 1, are held down with a predetermined thrust by a front bearing inner ring holder 9. The front bearings 3a, 3a are incorporated into a front bearing housing 7 and fixed in place by a front bearing outer ring holder 6. The rear bearing 3b is incorporated into a rear bearing housing 11 and fixed in place by a rear bearing outer ring holder 12. In FIG. 1, the front bearing lubrication nozzles 8, 8 and the rear bearing lubrication nozzle 10 are provided as parts that penetrate through the front bearing housing 7 and the bearing outer ring spacer 5, the rear bearing housing 11, and the rear bearing outer ring retainer 12, respectively, so as to connect to the front bearings 3a, 3a and the rear bearing 3b.

[0015] The lubrication device 200 is installed outside the spindle device 100 and supplies lubricating oil and air to the bearing unit 2 of the spindle device 100. The lubrication device 200 is composed of a mixer distributor 21, a lubricating oil pump 22, a compressed air source 23, and a lubricating oil control unit 24. The lubrication device 200 is connected to the spindle device 100 via pipes 16a, 16a, and 16b.

[0016] The operation of the lubricating device 200 will be described. The lubricating oil pump 22 intermittently repeats ON / OFF operation at time intervals set by a timer or the like to send the lubricating oil to the mixing distributor 21. In addition, the compressed air source 23 sends air to the mixing distributor 21 via a route separate from the lubricating oil sent from the lubricating oil pump 22. Then, after the lubricating oil and the air are mixed in the mixing distributor 21, the supply amount of the mixed lubricating oil and the air is adjusted by the lubricating oil control unit 24 and supplied to the pipes 16a, 16a, 16b. Finally, the lubricating oil and the air supplied to the pipes 16a, 16a are supplied to the front bearings 3a, 3a through the front bearing lubricating nozzles 8, 8 from the pipes 16a, 16a. Similarly, the lubricating oil and the air supplied from the lubricating device 200 to the pipe 16b are supplied to the rear bearing 3b through the rear bearing lubricating nozzle 10 from the pipe 16b.

[0017] The operation control unit 300 is a mechanism for controlling the spindle unit 100 and the lubrication unit 200, and is composed of a control unit 31 for operating the spindle unit 100 and the lubrication unit 200, a calculation unit 32 for performing various calculations, and a storage unit 33 for storing various information and parameters. The control unit 31 transmits and receives control signals to and from the calculation unit 32 according to an NC program 34 (described later) stored in the storage unit 33, adjusts the current supplied to the motor stator 14a based on the rotation speed information from the tachometer 15, and controls the spindle unit 100 so that the rotation speed of the spindle 1 of the spindle unit 100 (hereinafter simply referred to as the spindle rotation speed) becomes a predetermined value. The NC program 34 is a program in which various operation commands to the spindle unit 100 are prepared according to the workpiece, and an appropriate one can be selected and applied each time. The storage unit 33 stores information on the machine operation status, such as the operating time of the machine and the elapsed time since the end of the previous operation of the spindle unit 100, and parameters required for predetermined control.

[0018] The memory unit 33 pre-records the required amounts of lubricating oil and air flow from the lubrication device 200 to the bearing portion 2 according to conditions (hereinafter simply referred to as operating conditions) corresponding to combinations of the spindle rotation speed during cutting processing of the spindle device 100 and the load on the bearing portion 2 of the spindle device 100 during cutting processing (hereinafter simply referred to as cutting load).

[0019] The lubricating oil amount and the air flow rate for each operating condition recorded in the memory unit 33 will be described with reference to Fig. 2. Fig. 2 is a table showing the lubricating oil amount and the air flow rate for each operating condition. As shown in FIG. 2, the spindle speed is divided into three conditions: 0-33%, 34-67%, and 68-100%, with the maximum speed of the spindle 1 that can be operated in the spindle device 100 being 100%. The cutting load is divided into two conditions: 0-50% and 51-100%, with non-cutting being 0% and the output upper limit of the motor stator 14a being 100%. Thus, the amount of lubricant and the air flow rate are determined for a total of six operating conditions. For example, when the spindle speed is 0-33%, i.e., low speed, and the cutting load is 0-50%, i.e., low load, the influence of the air flow and centrifugal force accompanying the rotation is small, and it is easy to supply the lubricant to the bearing 2 by the lubricant device 200, and it can be said that the lubricant is unlikely to flow out of the bearing 2, so the amount of lubricant supplied from the lubricant device 200 and the air flow rate can be reduced.

[0020] Furthermore, even if the spindle rotation speed is low, when the cutting load is 51 to 100%, that is, in a high load state, the load on the bearing 2 increases and the bearing 2 generates heat, which may reduce the viscosity of the lubricating oil and reduce the oil film thickness in the bearing 2. To avoid this, it is necessary to increase the amount of lubricating oil supplied from the lubricating device 200. However, because the spindle rotation speed is low, the amount of air supplied from the lubricating device 200 may be small.

[0021] On the other hand, when the spindle rotation speed is 68-100%, i.e., high speed, the influence of the air currents and centrifugal forces associated with the rotation is large, making it difficult for the lubricating oil to be supplied to the bearing portion 2 by the lubrication device 200. Furthermore, it is possible that the lubricating oil is prone to leak out of the bearing portion 2. Therefore, regardless of the value of the cutting load, it is necessary to increase the amount of lubricating oil and air flow rate supplied by the lubrication device 200.

[0022] Next, the operation of the machine tool in this embodiment will be described. First, the user selects an NC program 34 suited to the workpiece. Next, the calculation unit 32 simulates the spindle speed and cutting load during cutting by the spindle unit 100 based on operation commands such as a spindle speed command and a cutting feed command of the selected NC program 34. Then, the calculation unit 32 classifies the simulation results by matching the simulated spindle speed and cutting load with the operation conditions of the spindle speed and cutting load recorded in the storage unit 33, and records the classification results in the storage unit 33.

[0023] Here, Fig. 3 shows the results of the simulation performed by the calculation unit 32 divided according to the operating conditions. In the example of Fig. 3, the results of the simulation are divided into three blocks, the first block to the third block. When the control unit 31 operates the spindle unit 100 according to the selected NC program 34, it compares the classified data of the simulation results by the calculation unit 32 recorded in the memory unit 33 with the lubricating oil amount and air flow rate for each operating condition recorded in the memory unit 33, and controls the lubricating oil control unit 24 to adjust the lubricating oil amount and air flow rate by the lubrication device 200.

[0024] Here, specific amounts of lubricating oil and air flow rates will be described with reference to FIG. 3 as an example. From FIG. 3, in the first block, the spindle rotation speed is low and the cutting load is high. Therefore, the control unit 31 increases the amount of lubricating oil provided by the lubricating device 200 while decreasing the air flow rate. Next, in the second block, the spindle rotation speed is low and the cutting load is low. Therefore, the control unit 31 supplies a small amount of lubricating oil and a small amount of air flow rate provided by the lubricating device 200. Finally, in the third block, the spindle rotation speed is high and the cutting load is low. The control unit 31 supplies a large amount of lubricating oil and a large amount of air flow rate provided by the lubricating device 200.

[0025] Furthermore, when the spindle unit 100 is actually operated, a time lag occurs before the lubricating oil moves from the lubrication device 200 to the front bearings 3a, 3a and the rear bearing 3b of the spindle unit 100, so the amount of lubricating oil supplied from the lubrication device 200 is changed a predetermined time before the spindle rotation speed is changed.

[0026] In addition to the above, in the operation control section 300, the control section 31 checks the stop time of the spindle unit 100 immediately before starting the NC program 34, and when a stop time exceeding a predetermined threshold is recognized, the control section 31 gradually increases the spindle speed to a target speed and performs a run-in operation before transitioning to an operation recorded in the NC program 34, thereby stabilizing the operation of the spindle unit 100. As a specific example, the control section 31 operates the spindle unit 100 while gradually increasing the spindle speed to 25%, 50%, and 75%, with the target spindle speed recorded in the NC program 34 being set as 100%. By performing such a run-in operation, it becomes possible to stabilize the lubrication state in the pipes 16a, 16a, and 16b that supply lubricating oil, the front bearings 3a, 3a, and the rear bearing 3b, etc., and to prevent unintentional transition to high-speed operation.

[0027] The machine tool of the above embodiment includes a spindle unit 100 that rotates the spindle 1 to perform cutting, a lubrication device 200 that supplies lubricating oil and air to the bearing unit 2 of the spindle unit 100, and an operation control unit 300 that controls the operation of the spindle unit 100 and the lubrication device 200. In addition, the memory unit 33 of the operation control unit 300 stores in advance the operation conditions according to the combination of the values ​​of the spindle speed and the cutting load, and the amount of lubricating oil and the air flow rate required for the operation conditions. When the control unit 31 of the operation control unit 300 operates the spindle unit 100 according to the NC program 34 stored in the memory unit 33, the calculation unit 32 of the operation control unit 300 performs a simulation of the spindle speed and the cutting load from the selected NC program 34, classifies the simulation results according to the operation conditions recorded in the memory unit 33, and records them in the memory unit 33. The control unit 31 operates the spindle unit 100 in accordance with the NC program 34, and at the same time adjusts the amount of lubricating oil and the air flow rate supplied by the lubrication unit 200 to the bearing unit 2 of the spindle unit 100 by comparing the amount of lubricating oil and the air flow rate required for the operating conditions recorded in the memory unit 33 with the simulation results classified by the calculation unit 32 based on the operating conditions and recorded in the memory unit 33.

[0028] Therefore, by adjusting the amount of lubricating oil and air supplied, taking into consideration not only the spindle rotation speed, i.e., the rotational speed, but also the load on the bearing 2 during cutting, it is possible to prevent damage to parts such as the bearing 2.

[0029] The present invention has been described above based on the illustrated examples, and the technical scope of the present invention is not limited to these. In this embodiment, the lubricant amount and the air flow rate are adjusted by the lubricant control unit 24, but a configuration in which the lubricant amount and the air flow rate are adjusted by other means may be adopted. As a means for adjusting the amount of lubricant, for example, changing the start time interval of the lubricant pump 22, or arranging multiple mixer distributors 21 with different lubricant discharge amounts and switching the connection destination of the lubricant pump 22, etc. are conceivable. It is also possible to use a valve that can variably discharge the lubricant. As a means for changing the air flow rate, for example, a regulator is used to set different supply pressures, or multiple paths having throttles with different throttling rates are prepared and switched between, etc.

[0030] 2 are merely examples, and are determined so as to more precisely control the amount of lubricating oil and the amount of air flow in accordance with the respective specifications, such as the upper limit of the spindle speed and the motor output, and the conditions of the spindle speed and the cutting load recorded in the memory unit 33 are determined as appropriate. For example, it is conceivable to set the spindle speed in five different ways, 0-20%, 21-40%, 41-60%, 61-80%, and 81-100%, and the cutting load in three different ways, 0-33%, 34-67%, and 68-100%, etc.

[0031] Also, depending on the type of bearing employed, the amount of lubricating oil may be individually controlled in the middle of the piping branched off from the mixer / distributor, rather than changing the amount of lubricating oil in all the lubricating oil supply circuits at once. For example, if the front bearings 3a, 3a are ball bearings and the rear bearing 3b is a cylindrical roller bearing, it is possible to reduce the amount of lubricating oil supplied to the piping 16b connected to the rear bearing lubricating nozzle 10 relative to the amount of lubricating oil supplied to the piping 16a, 16a connected to the front bearing lubricating nozzle 8. By adopting such a configuration, it is possible to realize an appropriate lubrication state for each bearing and prevent damage such as excessive surface pressure on the rolling surfaces of the bearings due to heat generation. [Explanation of symbols]

[0032] DESCRIPTION OF SYMBOLS 1··Main spindle, 2··Bearing section, 3a··Front bearing, 3b··Rear bearing, 4··Bearing inner ring spacer, 5··Bearing outer ring spacer, 6··Front bearing outer ring retainer, 7··Front bearing housing, 8··Front bearing lubrication nozzle, 9··Front bearing inner ring retainer, 10··Rear bearing lubrication nozzle, 11··Rear bearing housing, 12··Rear bearing outer ring retainer, 13··Rear bearing inner ring retainer, 14a··Motor stator, 14b··Rotor, 15··Tachometer, 16a, 16b··Pipes, 21··Mixing distributor, 22··Lubrication oil pump, 23··Compressed air source, 24··Lubrication oil control section, 31··Control section, 32··Calculation section, 33··Memory section, 34··NC program (operation program), 100··Main spindle device, 200··Lubrication device, 300··Operation control section.

Claims

1. A spindle device that rotates a tool attached to a spindle to perform cutting processing; a lubrication device for supplying lubricating oil and air to a bearing portion of the spindle; An operation control unit that controls the operation of the spindle device and the lubrication device, The operation control unit includes a control unit that operates the spindle device and the lubrication device, a calculation unit that performs various calculations, and a storage unit that stores an operation program for the spindle device, the operation program including at least a rotation speed command and a cutting feed command for the spindle, In addition to the operation program, the storage unit pre-records operation conditions corresponding to the respective values ​​of the spindle speed of the spindle and the cutting load on the bearing portion during cutting, and the amount of lubricating oil and the air flow rate required by the lubrication device for the operation conditions, The calculation unit classifies the operation program based on the rotation speed command and the cutting feed command in the operation program, the control unit operates the spindle unit in accordance with the operating program, and adjusts the amount of lubricating oil and the amount of air flow by a lubrication device by comparing the result of the classification with the amount of lubricating oil and the amount of air flow required for the operating conditions recorded in the memory unit.

2. 2. The machine tool according to claim 1, wherein the classification of the operation program is performed by the calculation unit performing a simulation of the spindle rotation speed and the cutting load according to the operation program, based on the results of the simulation.

3. The memory unit stores a plurality of the operating programs in accordance with the workpiece to be cut, 3. The machine tool according to claim 1, wherein the control unit operates the spindle device in accordance with the operation program selected from a plurality of the operation programs.

4. 3. The machine tool according to claim 1, wherein the control unit, when operating the spindle device in accordance with the operation program to change a spindle rotation speed, changes an amount of lubricating oil and / or an air flow rate by the lubrication device retroactively for a predetermined time period.

5. 3. The machine tool according to claim 1 or 2, characterized in that, when the spindle device is stopped for a period equal to or longer than a predetermined threshold value, the control unit causes the spindle device to perform an operation in accordance with the operation program after gradually increasing the spindle rotation speed.

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