CN111113149A - Machine tool - Google Patents
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- CN111113149A CN111113149A CN201911035959.8A CN201911035959A CN111113149A CN 111113149 A CN111113149 A CN 111113149A CN 201911035959 A CN201911035959 A CN 201911035959A CN 111113149 A CN111113149 A CN 111113149A
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- machining
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
- B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
- B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P23/00—Machines or arrangements of machines for performing specified combinations of different metal-working operations not covered by a single other subclass
- B23P23/04—Machines or arrangements of machines for performing specified combinations of different metal-working operations not covered by a single other subclass for both machining and other metal-working operations
Abstract
The invention provides a machine tool. The machine tool is provided with: a machining load measuring instrument that measures a machining load during machining of a workpiece by a tool; a threshold value storage unit that stores a threshold value for correcting a surface state of a tool or replacing the tool, the threshold value being determined based on information on a relationship between a workpiece index indicating the surface state of the workpiece and a machining load; and an implementation determination unit that determines whether or not the surface state of the tool or the replacement of the tool can be implemented, based on the machining load and a threshold value for each of the workpieces measured when the plurality of workpieces are continuously machined in sequence.
Description
Technical Field
The present invention relates to machine tools.
Background
Patent document 1 describes that, when the surface roughness of a workpiece does not reach a predetermined reference after the grinding wheel is finished, the next finishing is performed. Also, the surface roughness of the workpiece is measured by an optical sensor.
Patent document 1: japanese patent laid-open publication No. 2017-200719
However, since foreign matter such as coolant and chips may adhere to the workpiece in a state of being mounted on the grinding machine, the surface roughness of the workpiece may not be measured with high accuracy. Although the surface roughness can be measured with high accuracy by removing the coolant and the foreign matter, a corresponding device is required, resulting in high cost. In addition, the use of dedicated sensors also increases costs. In addition, it is desirable to determine the timing of dressing the grinding wheel without using a sensor that measures the surface roughness of the workpiece.
Disclosure of Invention
An object of one embodiment of the present invention is to provide a machine tool capable of measuring the surface state of a workpiece or correcting the surface state of a tool or determining the replacement of a tool without using a dedicated sensor.
(1. first machine tool)
The first machine tool is provided with: a machining load measuring instrument that measures a machining load during machining of a workpiece by a tool; a relation information storage unit that stores preset relation information between the machining load and either one of a workpiece index indicating a surface state of the workpiece and a tool index indicating a surface state of the tool; and an estimating unit configured to estimate one of the workpiece index and the tool index based on the machining load on each of the workpieces measured when the plurality of workpieces are continuously machined in sequence and the relationship information stored in the relationship information storage unit.
An index indicating the surface state of a workpiece or an index indicating the surface state of a tool is estimated using a machining load during machining. Therefore, even if foreign matter such as coolant and chips adheres to the surface of the workpiece, the index can be estimated with high accuracy. The workpiece index includes, for example, the surface roughness of the workpiece. The tool index includes, for example, an index indicating the roughness of the surface of the tool.
(2. second machine tool)
The second machine tool includes: a machining load measuring instrument that measures a machining load during machining of a workpiece by a tool; a relation information storage unit that stores preset relation information between the machining load and either one of a workpiece index indicating a surface state of the workpiece and a tool index indicating a surface state of the tool; an estimating unit that estimates one of the workpiece index and the tool index based on the machining load for each of the workpieces measured when a plurality of the workpieces are continuously machined in sequence and the relationship information stored in the relationship information storage unit; and an implementation determination unit that determines whether or not the surface state of the tool can be corrected or the tool can be replaced, based on one of the estimated workpiece index and the estimated tool index.
An index indicating the surface state of a workpiece or an index indicating the surface state of a tool is estimated using a machining load during machining. Therefore, even if foreign matter such as coolant and chips adheres to the surface of the workpiece, the index can be estimated with high accuracy. The workpiece index includes, for example, the surface roughness of the workpiece. The tool index includes, for example, an index indicating the roughness of the surface of the tool. Then, based on either the estimated workpiece index or the estimated tool index, it is determined whether or not the surface state of the tool can be corrected or the tool can be replaced. Therefore, it is possible to determine whether or not the surface state of the tool can be corrected or the tool can be replaced without using a dedicated sensor, and therefore, low cost can be achieved.
(3. third machine tool)
The third machine tool includes: a machining load measuring instrument that measures a machining load during machining of a workpiece by a tool; a threshold value storage unit that stores a threshold value that is determined based on information on a relationship between the machining load and either one of a workpiece index indicating a surface state of the workpiece and a tool index indicating a surface state of the tool, and that is used for correction of the surface state of the tool or replacement of the tool; and an implementation determination unit that determines whether or not to implement the correction of the surface state of the tool or the replacement of the tool, based on the machining load for each of the workpieces measured when the plurality of workpieces are continuously machined in sequence and the threshold stored in the threshold storage unit.
In this way, the machining load and the threshold are used to determine whether or not the surface state of the tool can be corrected or the tool can be replaced. Therefore, it is possible to determine whether or not the surface state of the tool can be corrected or the tool can be replaced without using a dedicated sensor, and therefore, low cost can be achieved. The threshold value is determined based on information on the relationship between the index indicating the surface state of the workpiece or the index indicating the surface state of the tool and the machining load. That is, even if the determination of the feasibility is made based on the machining load, the determination is made in consideration of the surface state of the workpiece or the surface state of the tool. Therefore, the surface state of the tool can be corrected or the tool can be replaced at an appropriate timing.
Drawings
Fig. 1 is a front view of a machine tool.
Fig. 2 is a plan view of the machine tool of fig. 1, showing portions other than the conveying device.
Fig. 3 is a functional block diagram of a first example of a machine tool.
Fig. 4 is a diagram showing a change in machining load from the start to the end of machining when one workpiece is machined.
Fig. 5 is a graph showing the correlation between the feature amount of the machining load and the surface roughness.
Fig. 6 is a diagram showing the transition of the estimated surface roughness of the workpiece with respect to the number of finished workpieces.
Fig. 7 is a functional block diagram of a second example of the machine tool.
Fig. 8 is a diagram showing changes in the feature quantity of the machining load with respect to the number of machined workpieces after the finishing.
Description of reference numerals:
1 … machine tool; 2 … machine body; 3 … hopper; 4 … surface condition measuring instrument; 5 … conveying device; 11 … stand; 12 … a workbench; 12a, 13a, 14a, 15a, Ta … drive; 13 … headstock; 13a … drive means; 14 … tailstock; 14a … drive means; 15 … grinding wheel table; 15a … drive means; 16 … size control device; 17 … grinding wheel truing device; 18 … coolant device (drive device); 19 … control device; 20 … operating panel; 21 … processing load measuring instrument; 22 … processing control part; 23 … a feature value calculation unit; 24 … relation information storage; a 25 … estimating unit; 26 … implementing a determination unit; 27 … embodiment; 28 … information determination unit; 31 … processing load measuring instrument; 32 … processing control part; 33 … a feature value calculation unit; 34 … threshold value storage part; 35 … implementing a determination unit; 36 … embodiment; 37 … relation information storage section; 38 … estimating unit; 39 … information determination unit; a … rough machining procedure; B. b1, B2 and B3 … finishing; t … cutter (grinding wheel); ta … drive; th1, Th2 … thresholds; w … workpiece.
Detailed Description
(1. Structure of machine tool 1)
The structure of the machine tool 1 will be described with reference to fig. 1 and 2. The machine tool 1 includes a machine tool main body 2, a stocker 3, a surface condition measuring instrument 4, and a transport device 5. The machine tool body 2 is a machine for machining a workpiece W with a tool T. The machine tool body 2 is a machine that performs machining such as cutting, grinding, cutting, forging, and bending. The machine tool body 2 is, for example, a grinding machine, a lathe, a milling machine, a machining center, or the like.
The stocker 3 is a place for storing the workpiece W before processing and the workpiece W after processing. The stocker 3 holds a tubular workpiece W in a vertically standing state, for example. Here, the stockers 3 may include a first stocker for storing the workpiece W before processing and a second stocker for storing the workpiece W after processing.
The surface condition measuring instrument 4 is an external measuring instrument disposed outside the machine tool body 2. The surface condition measuring instrument 4 measures various values regarding the surface condition of the workpiece W machined in the machine tool body 2. The surface condition measuring instrument 4 is mainly a dedicated device that measures a value of the workpiece W with respect to the shape. The surface condition measuring instrument 4 measures at least the actual surface roughness (equivalent to the actual surface condition) of the workpiece W as one of the indexes indicating the surface condition of the workpiece W. The surface condition measuring instrument 4 may be an optical sensor or a magnetic sensor capable of measuring the surface of the workpiece W in a non-contact manner, or may be a contact sensor capable of measuring the surface of the workpiece W by tracing the surface with a stylus.
Here, the actual surface roughness measured by the surface condition measuring instrument 4 is, for example, a surface roughness parameter specified in ISO 25178. The surface roughness parameters are, for example, an arithmetic average height Sa, a maximum height Sz, a root mean square height Sq, a gradient (degree of deviation) Ssk, a maximum peak height Sp, and the like. Of course, other predetermined indexes can be applied as the surface roughness parameter.
Further, the surface condition measuring instrument 4 can also measure a value other than the actual surface roughness. The surface of the workpiece W to be measured by the surface condition measuring instrument 4 is not coated with coolant or foreign matter (chips, etc.). Therefore, the surface condition measuring instrument 4 can perform measurement with high accuracy. Here, the surface condition measuring instrument 4 does not set all the workpieces W machined in the machine tool body 2 as the measurement target, but sets only a workpiece W selected from among a plurality of workpieces W machined in sequence as the measurement target. In this example, the surface condition measuring instrument 4 is disposed between the machine tool main body 2 and the stocker 3.
The transport device 5 transports the workpiece W between the machine tool main body 2, the stocker 3, and the surface condition measuring instrument 4. The conveying device 5 carries the workpiece W in and out from above the machine tool main body 2. However, the conveying device 5 may carry the workpiece W in and out from the front surface of the machine tool main body 2. In this example, the conveyance device 5 includes: a beam 5a provided to extend in the horizontal direction; and a conveyor main body 5b that is movable in the horizontal direction along the beam 5a and movable in the vertical direction with respect to the beam 5 a.
(2. operation of machine tool 1)
The conveyor 5 holds the workpiece W stored in the stocker 3 before machining, and carries the workpiece W into the machine tool main body 2. Next, the machine tool body 2 machines the workpiece W carried in. Next, the conveyor 5 carries out the processed workpiece W from the machine tool main body 2. The carried-out workpiece W is stored in the stocker 3. Among them, the conveying device 5 conveys a workpiece W selected from among a plurality of sequentially processed workpieces W from the machine tool main body 2 to the surface condition measuring instrument 4. Then, the surface condition measuring instrument 4 measures the surface roughness of the workpiece W. The workpiece W whose measurement is completed is conveyed to the stocker 3 by the conveying device 5. Then, the above-described processing is sequentially repeated.
(3. Structure of machine tool body 2)
The detailed structure of the machine tool body 2 will be described with reference to fig. 1 and 2. As an example of the machine tool body 2, a grinding machine is shown as an example. The grinding machine grinds and processes the workpiece W by a grinding wheel (tool T). The machine tool body 2 can be a cylindrical grinder, a cam grinder, or any other grinder. In this example, a grinding machine in which a table moves laterally is illustrated as the machine tool main body 2. However, a cylinder grinder in which the grinding wheel table moves laterally may be applied to the machine tool main body 2.
A grinding machine as a machine tool body 2 mainly includes a bed 11, a table 12, a headstock 13, a tailstock 14, a grinding wheel table 15, a grinding wheel (tool T), a dimension control device 16, a grinding wheel dressing device 17, a coolant device 18, a control device 19, and an operation panel 20.
The base 11 is fixed on the setting surface. The table 12 is formed in an elongated shape. The table 12 is provided on the upper surface of the bed 11 so as to be movable in the center axis direction (Z-axis direction) of the workpiece W. Specifically, the table 12 is moved by driving a driving device 12a provided in the bed 11.
The headstock 13 is provided on the upper surface of the table 12, and supports the workpiece W rotatably about the central axis (about the Z axis) of the workpiece W. The tailstock 14 is provided on the upper surface of the table 12 at a position facing the headstock 13. The headstock 13 and the tailstock 14 rotatably support both ends of the workpiece W. The workpiece W is rotated by driving of a drive device 13a provided in the headstock 13 and a drive device 14a provided in the tailstock 14.
The grinding wheel table 15 is provided on the upper surface of the bed 11 so as to be movable in a direction (X-axis direction) toward and away from the workpiece W. The grinding wheel table 15 is moved by driving a driving device 15a provided in the bed 11.
The grinding wheel T is formed in a disk shape and rotatably supported by the grinding wheel table 15. The grinding wheel T is rotated by driving of a driving device Ta provided on the grinding wheel table 15. For example, as shown in fig. 2, the drive device Ta may drive the grinding wheel T via a belt and a pulley, or may be arranged coaxially with the grinding wheel T and directly driven without the belt and the pulley.
The grinding wheel T is configured by fixing a plurality of abrasive grains with a binder. Among the abrasive particles, there are general abrasive particles and superabrasive particles. As general abrasive grains, ceramic materials such as alumina and silicon carbide are known. The superabrasive grains are diamonds and CBN. In this example, a larger number of superabrasive particles of the workpiece W to be processed is used. This reduces the frequency of dressing and replacement of the grinding wheel T, and can reduce the cost and cycle time.
The dimension control device 16 includes a pair of contactors that are provided on the upper surface of the table 12 and can be brought into contact with the outer peripheral surface of the workpiece W, and measures the dimension (diameter) of the machining portion of the workpiece W. The dimension control signal based on the dimension control device 16 is used for switching the machining process (rough machining and finish machining) in the machining control by the control device 19 described later.
The grinding wheel truing device 17 trues the surface condition of the grinding wheel T. The grinding wheel truing device 17 is a device for performing truing as truing of the grinding wheel T. The grinding wheel dresser 17 also has a function of measuring the size (diameter) of the grinding wheel T. Here, the truing is a truing operation, which is an operation of forming the grinding wheel T in accordance with the shape of the workpiece W after the grinding wheel T is worn out by the grinding, an operation of removing a deviation (chatter れ) of the grinding wheel T by a single wear (sheet wear), or the like.
The coolant device 18 supplies coolant to a grinding point of the workpiece W by the grinding wheel T. The coolant device 18 cools the recovered coolant to a predetermined temperature, and supplies the cooled coolant to the grinding point again.
The control device 19 controls the drive devices 12a, 13a, 14a, 15a, and Ta based on the NC program and the control program of the PLC. The NC program is generated based on the shape of the workpiece W, the shape of the grinding wheel T, machining conditions, supply timing information of the coolant, timing information of the truing of the grinding wheel T, and the like. The control program of the PLC operates the output device in response to the ON/OFF of the command signal inputted to the device.
That is, the controller 19 controls the respective driving devices 12a, 13a, 14a, 15a, and Ta, the coolant device 18, and the like based on the NC program and the control program of the PLC, and grinds the workpiece W. In particular, the controller 19 grinds the workpiece W until the workpiece W becomes a finished shape based on the diameter of the workpiece W measured by the size controller 16.
The operation panel 20 is a device disposed on the front surface of the machine tool main body 2 for various operations by a worker. The operation panel 20 also functions as a display device for displaying various information.
(4. functional structure of first example of machine tool 1)
The functional configuration of the first example of the machine tool 1 will be described with reference to fig. 3 to 6. As shown in fig. 3, the machine tool 1 includes driving devices 12a, 13a, 14a, 15a, Ta, 18, a surface condition measuring instrument 4, a machining load measuring instrument 21, a machining control unit 22, a feature value calculating unit 23, a relationship information storage unit 24, an estimating unit 25, an implementation determining unit 26, an implementation unit 27, and an information determining unit 28. Here, the processing control unit 22, the feature amount calculation unit 23, the relationship information storage unit 24, the estimation unit 25, the implementation determination unit 26, the implementation unit 27, and the information determination unit 28 constitute a processing unit in the control device 19.
As described above, the driving devices 12a, 13a, 14a, 15a, Ta, 18 drive the respective members in the machine tool body 2. The surface condition measuring instrument 4 is an external measuring instrument disposed outside the machine tool body 2, and measures the surface condition of the workpiece W. The surface condition measuring instrument 4 does not measure all of the workpieces W, but only a selected part of the workpieces W.
The machining load measuring instrument 21 measures the machining load while the plurality of workpieces W are continuously machined in sequence by the grinding wheel T. The machining load corresponds to the machining resistance. For example, the machining load measuring instrument 21 measures grinding resistance in grinding. Among these, there are measuring units of various machining loads. As a first type, there is a means for measuring the power of a driving device for moving the tool T during machining as a machining load. In this example, the power of the drive device that rotationally drives the grinding wheel T can be made to be the grinding resistance. At this time, the machining load measuring instrument 21 is a sensor for measuring the power of the driving device Ta for rotationally driving the grinding wheel T, and measures the power as the machining load (e.g., grinding resistance). Hereinafter, the power is referred to as the power of the grinding wheel T.
As a second type, there is a unit that measures a load applied to a member supporting the workpiece W as a processing load. In this example, the force that the headstock 13 receives from the workpiece W can be made the grinding resistance. In this case, the machining load measuring instrument 21 is a force sensor provided in a portion of the headstock 13 that supports the workpiece W, and measures the force as the machining load. In addition to the case where the machining load is measured by the sensor as in the first and second cases, the machining load may be obtained by calculation.
In addition to the above, the machining load measuring instrument 21 may use a sensor for measuring the rotation state of the grinding wheel T or the workpiece W, or may use a sensor for measuring the vibration of the headstock 13, the tailstock 14, the grinding wheel table 15, the bed 11, the bearing portion for supporting the rotation, or the like of the machine tool body 2. The sensor for measuring the rotation state is, for example, an optical sensor, a laser sensor, an ultrasonic sensor, an eddy current sensor, an electrostatic capacitance sensor, a potentiometer, an acceleration sensor, or the like. The sensor for measuring vibration is a piezoelectric sensor, a capacitance sensor, an acceleration sensor, a velocity sensor, or the like.
The machining load measuring instrument 21 may be a flow meter that measures the flow rate of the coolant, or may measure the temperature of the coolant. The flow rate and temperature of the coolant are parameters that affect the processing load. Therefore, the machining load measuring instrument 21 may measure the flow rate or the temperature of the coolant.
In the above description, the machining load measuring instrument 21 is exemplified as an example of a measurement target. In addition, the machining load measuring instrument 21 may measure a plurality of objects that affect the machining load. For example, the machining load measuring instrument 21 may measure a plurality of objects such as the power of a driving device that rotationally drives the grinding wheel T, the vibration of the headstock 13, and the flow rate of the coolant.
The machining control unit 22 is a main function of the control device 19, and controls the drive devices 12a, 13a, 14a, 15a, and Ta based on an NC program and a control program of a PLC. The machining control unit 22 switches the machining process (rough machining and finish machining) based on the dimension control signal from the dimension control device 16.
Rough machining and finish machining are described with reference to fig. 4. Fig. 4 shows a machining load (power of the grinding wheel T) when one workpiece W is machined. After the workpiece W is machined in the rough machining step a, the machining control unit 22 machines the workpiece W in the finish machining step B. The finishing step B is divided into three steps B1 to B3. For example, the rough machining step a is a rough grinding step, and the finish machining step B is a finish grinding step B1, a fine grinding step B2, and a sparkless grinding step B3. That is, the machining control unit 22 machines one workpiece W by a plurality of machining processes using the tool T.
The machining load is the largest in the rough machining step a, and the machining load is smaller in the finish machining step B than in the rough machining step a. In the finishing step B, the finishing steps B1, B2 and B3 are arranged in descending order of the machining load. The machining control unit 22 performs switching among the steps A, B1, B2, and B3 based on the dimension control signal of the dimension control device 16.
The feature value calculation unit 23 calculates a feature value relating to the machining load using the machining load of each workpiece W measured by the machining load measuring instrument 21 when the plurality of workpieces W are continuously machined in sequence. During machining of one workpiece W, the feature amount calculation unit 23 calculates a feature amount based on the behavior of the machining load as shown in fig. 4. Here, the feature amount can be any one of a maximum value, an average value, a maximum value of first order differential, an average value of first order differential, a mode, dispersion, standard deviation, kurtosis, skewness, and the like. The feature amount calculation unit 23 may calculate only one kind of feature amount, or may calculate a plurality of kinds of feature amounts. In the processing of the estimation unit described later, it is effective to use a plurality of kinds of feature quantities when applying machine learning.
The feature amount calculation unit 23 may calculate a feature amount related to a machining load in a predetermined machining step among the machining loads in the process of machining the single workpiece W. For example, the feature amount calculation unit 23 may calculate the feature amount related to the machining load in the rough machining step a shown in fig. 4. The feature amount calculation unit 23 may calculate the feature amount related to the machining load in the finishing step B shown in fig. 4 or the detailed steps B1, B2, and B3. The feature amount calculation unit 23 may calculate feature amounts in a plurality of machining processes when calculating a plurality of kinds of feature amounts. For example, the feature amount calculation unit 23 may calculate both the feature amount in the rough machining step a and the feature amount in the finish machining step B.
When the machining load measuring instrument 21 measures a plurality of objects with respect to one workpiece W, the feature amount calculation unit 23 may calculate the feature amount of each of the plurality of objects.
The relation information storage unit 24 stores relation information between a workpiece index indicating a surface state of the workpiece W and the machining load (information indicating a correlation between the workpiece index indicating the surface state of the workpiece W and the machining load). Here, the workpiece index is, for example, a value corresponding to the surface roughness of the workpiece W. The surface roughness is a surface roughness parameter specified in ISO25178, and the like. The relationship information stored in the relationship information storage unit 24 is set in advance. Here, in addition to the workpiece index, the relationship information storage unit 24 may store relationship information between a tool index indicating a surface state of the tool T and the machining load (information indicating a correlation between the tool index indicating the surface state of the tool T and the machining load) instead of the workpiece index.
Here, after the grinding wheel T is finished, a plurality of workpieces W are sequentially machined by the grinding wheel T. Fig. 5 is a diagram showing a relationship between the machining number of the workpiece W and the characteristic amount (for example, the maximum value) of the machining load at this time, and a relationship between the machining number and the surface roughness of the workpiece W.
As shown in fig. 5, the machining load represents the highest value in the process of machining the first workpiece W after the truing of the grinding wheel T. Thereafter, as the number of machining of the workpiece W increases, the machining load decreases. The reason for this is as follows. The surface condition of the grinding wheel T has more flat portions by the truing. That is, the surface of the abrasive grains is in a state of having many flat portions. Further, the surface state of the grinding wheel T becomes rough due to repeated machining. That is, the flat portion of the surface of the abrasive grains is sharpened by the scraping. Therefore, as described above, as the number of machining of the workpiece W increases, the machining load decreases.
Further, the surface condition of the grinding wheel T is transferred to the surface condition of the workpiece W. Therefore, the surface condition of the workpiece W depends on the surface condition of the grinding wheel T. Specifically, as shown in fig. 5, when the feature amount of the machining load is decreased, the surface roughness of the workpiece W is increased. The reason for this is that as the number of machining increases, the surface state of the grinding wheel T becomes rough, the surface state of the grinding wheel T becomes rougher, and the surface state of the workpiece W becomes rougher. From this, it is understood that the characteristic amount of the machining load has a predetermined relationship with the surface roughness of the workpiece W.
Therefore, the relation information storage unit 24 stores relation information between the characteristic amount (for example, the maximum value) of the machining load and the surface roughness as the workpiece index, for example. The relationship information storage unit 24 may store relationship information between the characteristic amount of the machining load and the surface state of the grinding wheel T as the tool index, for example.
Here, the relation information stored in the relation information storage unit 24 may be a relation between a characteristic amount (for example, a maximum value) of the machining load and the surface roughness as the workpiece index as shown in fig. 5. In this way, if the object of the relationship information is the relationship between one feature amount and one workpiece index, the relationship information storage unit 24 can store the map, the relational expression, and the like.
However, the object of the relationship information may be a relationship between a plurality of feature amounts and one workpiece index. At this time, the relationship information storage unit 24 may store the images and the relational expressions. In addition, the relationship information storage unit 24 may store, as the relationship information, a learning model indicating a relationship between the feature quantity of the machining load and the workpiece index generated by machine learning. The relationship information storage unit 24 may store, as the relationship information, a learning model indicating a relationship between the feature quantity of the machining load and the tool index generated by machine learning.
The estimation unit 25 acquires the feature amount calculated by the feature amount calculation unit 23. The acquired feature amount corresponds to a feature amount that is an object of the relationship information. That is, when the object of the relationship information is a type of feature amount, the estimation unit 25 acquires the type of feature amount. When the object of the relationship information is a plurality of types of feature values, the estimation unit 25 acquires the plurality of types of feature values. The estimation unit 25 acquires the relationship information stored in the relationship information storage unit 24.
Next, the estimation unit 25 estimates a workpiece index or a tool index based on the acquired feature amount of the machining load and the relationship information. The estimated object corresponds to the object of the relationship information. For example, the estimation unit 25 estimates the surface roughness of the workpiece W as the workpiece index based on one of the feature amounts and the relationship information regarding the machining load during machining of one workpiece W.
The execution determination unit 26 determines whether or not the grinding wheel T can be finished or replaced, based on any one of the workpiece index and the tool index estimated by the estimation unit 25. For example, the execution determination unit 26 determines whether or not the finish of the grinding wheel T is to be executed, based on the surface roughness of the workpiece W as the workpiece index estimated by the estimation unit 25.
In order to determine whether or not the grinding wheel T can be finished, the execution determination unit 26 stores in advance a threshold Th1 that can be compared with the estimated surface roughness of the workpiece W, for example. As shown in fig. 6, the execution determination unit 26 determines that the finish of the grinding wheel T is executed when the estimated surface roughness of the workpiece W exceeds the threshold Th1 (exceeds the threshold Th 1). In fig. 6, it is determined that the grinding wheel T is trued at the time Tu.
The implementation unit 27 performs processing corresponding to the determination result of the implementation determination unit 26. For example, when the execution determination unit 26 determines that the finishing of the grinding wheel T is to be performed, the execution unit 27 can drive the driving device to finish the grinding wheel T. When it is determined that the finishing is performed, the execution unit 27 may display finishing execution guide information or finishing execution information on the operation panel 20. When the execution determination unit 26 determines that the grinding wheel T is to be replaced, the execution unit 27 may display a replacement guide on the operation panel 20.
The information determination unit 28 acquires the surface roughness of the workpiece W estimated by the estimation unit 25 and the actual surface roughness of the workpiece W measured by the surface condition measuring instrument 4. However, the surface condition measuring instrument 4 does not measure all the workpieces W, but measures a part of the workpieces W selected from a plurality of workpieces W that have been sequentially machined.
Then, the information determination unit 28 compares the estimated surface roughness of the workpiece W with the actual surface roughness. Here, the comparison target is the surface roughness for the same workpiece W. The information determination unit 28 determines whether or not the relationship information stored in the relationship information storage unit 24 is good based on the result of the comparison. For example, when the both are deviated, the information determination unit 28 determines that the relationship information is not good. There are various causes of the deviation between the two, for example, a change in the surrounding environment, a change in aging of the machine tool main body 2, and the like. When determining that the current relationship information is not good, the information determination unit 28 can update the relationship information to information corresponding to the current situation.
In addition, when the relationship information is a learning model for machine learning, the information determination unit 28 can update the learning model. For example, when the estimated surface roughness of the workpiece W is frequently deviated from the actual surface roughness, the information determination unit 28 can update the learning model by performing learning again by further adding the learning data learned last time. In this way, the learning model can be updated based on further acquired information.
An index indicating the surface condition of the workpiece W or an index indicating the surface condition of the grinding wheel T is estimated using the machining load during machining. Therefore, even if foreign matter such as coolant and chips adheres to the surface of the workpiece W, the index can be estimated with high accuracy. The workpiece index includes, for example, the surface roughness of the workpiece W. The tool index includes, for example, an index indicating the roughness of the surface of the grinding wheel T. Then, based on either the estimated workpiece index or the estimated tool index, it is determined whether the grinding wheel T can be trued or replaced. Therefore, it is possible to determine whether or not the grinding wheel T can be finished or replaced without using a dedicated sensor, and therefore, low cost can be achieved.
(5. modification)
As described above, the relational information storage unit 24 stores the relational information between the characteristic amount of the machining load and the surface roughness of the workpiece W as the workpiece index. In addition, the relationship information stored in the relationship information storage unit 24 may be related to indices such as a state of high-frequency vibration of the workpiece W, a state of a machining deteriorated layer of the workpiece W (a state of machining burn, etc.), a state of the tool T (for example, a state related to a life and a breakage), a machining state of the machine tool main body 2 (optimal machining, a spindle abnormality, a failure of the automatic tool changer, a failure of the automatic pallet changer), a machining time of the workpiece W (optimal machining), and the like, in place of the workpiece index. In this case, the estimating unit 25 can estimate the index in the relationship information. For example, the estimation unit 25 may estimate a state of high-frequency vibration of the workpiece W, a state of a work-affected layer of the workpiece W, and the like.
(6. functional Structure of second example of machine tool 1)
The functional configuration of the second example of the machine tool 1 will be described with reference to fig. 7 to 8. As shown in fig. 7, the machine tool 1 includes drive devices 12a, 13a, 14a, 15a, Ta, 18, a surface condition measuring instrument 4, a machining load measuring instrument 31, a machining control unit 32, a feature value calculating unit 33, a threshold value storage unit 34, an implementation determining unit 35, an implementation unit 36, a relationship information storage unit 37, an estimating unit 38, and an information determining unit 39. Here, the processing control unit 32, the feature amount calculation unit 33, the threshold value storage unit 34, the implementation determination unit 35, the implementation unit 36, the relationship information storage unit 37, the estimation unit 38, and the information determination unit 39 constitute a processing unit in the control device 19.
The driving devices 12a, 13a, 14a, 15a, Ta, 18, the surface condition measuring instrument 4, the machining load measuring instrument 31, the machining control unit 32, the feature amount calculating unit 33, the relationship information storage unit 37, and the estimating unit 38 are substantially the same as the driving devices 12a, 13a, 14a, 15a, Ta, 18, the surface condition measuring instrument 4, the machining load measuring instrument 21, the machining control unit 22, the feature amount calculating unit 23, the relationship information storage unit 24, and the estimating unit 25 in the first example.
The threshold value storage unit 34 stores a threshold value Th2 (shown in fig. 8) for determining whether or not the grinding wheel T can be trued or replaced. The threshold Th2 is determined based on the relation information between the workpiece index indicating the surface state of the workpiece W and the feature amount of the machining load. The relationship information corresponds to the relationship information stored in the relationship information storage unit 24 in the first example. The threshold Th2 may be determined based on information on the relationship between a tool index indicating the surface state of the grinding wheel T and the characteristic amount of the machining load.
The implementation determination unit 35 determines whether or not the grinding wheel T can be finished or replaced based on the feature value calculated by the feature value calculation unit 33 and the threshold value Th2 stored in the threshold value storage unit 34. For example, the implementation determination unit 35 compares the characteristic amount of the processing load of the workpiece W with the threshold Th 2.
Here, as shown in fig. 8, as for the feature amount (for example, the maximum value) of the processing load of the workpiece W, the feature amount of the processing load decreases as the number of processes increases. Therefore, when the characteristic amount of the machining load exceeds the threshold Th2 (when the characteristic amount of the machining load is lower than the threshold Th 2), it is determined that the truing of the grinding wheel T is performed. In fig. 8, it is determined that the grinding wheel T is trued at the time Tu.
The implementation unit 36 performs processing corresponding to the determination result of the implementation determination unit 35. For example, when the execution determination unit 35 determines that the finishing of the grinding wheel T is to be performed, the execution unit 36 can drive the driving device to finish the grinding wheel T. When it is determined that the finishing is performed, the execution unit 36 may display finishing execution guide information or finishing execution information on the operation panel 20. When the execution determination unit 35 determines to replace the grinding wheel T, the execution unit 36 may display a replacement guide on the operation panel 20.
The information determination unit 39 compares the surface roughness of the workpiece W estimated by the estimation unit 38 with the actual surface roughness measured by the surface condition measuring instrument 4. Here, the comparison target is the surface roughness for the same workpiece W. The information determination unit 39 determines the quality of the threshold Th2 stored in the threshold storage unit 34 based on the result of the comparison. For example, when the both are deviated, the information determination unit 39 determines that the threshold value is not good. There are various causes of the deviation between the two, for example, a change in the surrounding environment, a change in aging of the machine tool main body 2, and the like. When determining that the current threshold Th2 is not good, the information determination unit 39 can update the threshold Th2 to a value corresponding to the current situation.
The information determination unit 39 may determine the quality of the relationship information stored in the relationship information storage unit 37 based on the comparison result between the estimated surface roughness of the workpiece W and the actual surface roughness. For example, when the both are deviated, the information determination unit 39 determines that the relationship information is not good. When determining that the current relationship information is not good, the information determination unit 28 can update the relationship information to information corresponding to the current situation.
In addition, when the relationship information is a learning model for machine learning, the information determination unit 39 can update the learning model. For example, when the estimated surface roughness of the workpiece W and the actual surface roughness are frequently deviated from each other, the information determination unit 39 can update the learning model by further adding the learning data learned last time and performing learning again. In this way, the learning model can be updated based on further acquired information.
As described above, the machining load and the threshold value are used to determine whether the grinding wheel T can be trued or replaced. Therefore, it is possible to determine whether or not the grinding wheel T can be finished or replaced without using a dedicated sensor, and therefore, low cost can be achieved. The threshold Th2 is determined based on information on the relationship between the index indicating the surface condition of the workpiece W or the index indicating the surface condition of the grinding wheel T and the machining load. That is, even if the determination of the feasibility is made based on the machining load, the determination is made in consideration of the surface state of the workpiece W or the surface state of the grinding wheel T. Therefore, the grinding wheel T can be finished or replaced at an appropriate timing.
Claims (19)
1. A machine tool is characterized by comprising:
a machining load measuring instrument that measures a machining load during machining of a workpiece by a tool;
a relation information storage unit that stores preset relation information between the machining load and either one of a workpiece index indicating a surface state of the workpiece and a tool index indicating a surface state of the tool; and
and an estimating unit configured to estimate one of the workpiece index and the tool index based on the machining load for each of the workpieces measured when the plurality of workpieces are continuously machined in sequence and the relationship information stored in the relationship information storage unit.
2. The machine tool of claim 1,
the machine tool is further provided with an implementation determination unit,
the implementation determination unit determines whether or not the surface state of the tool can be corrected or the tool can be replaced, based on one of the estimated workpiece index and the estimated tool index.
3. The machine tool according to claim 1 or 2,
the machine tool further comprises a feature value calculation unit,
the feature value calculation unit calculates a feature value relating to the machining load during machining of one of the workpieces,
the relationship information is information having a correlation between the feature amount and the workpiece index or information having a correlation between the feature amount and the tool index.
4. The machine tool of claim 3,
the feature value calculation unit calculates a plurality of types of feature values related to the machining load during machining of one workpiece,
the relationship information is information having a correlation between a plurality of kinds of the feature amounts and the workpiece index, or information having a correlation between a plurality of kinds of the feature amounts and the tool index.
5. The machine tool of claim 3,
the machine tool is further provided with a machining control unit,
the machining control unit machines one of the workpieces by the tool in a plurality of machining processes,
the feature value calculation unit calculates the feature value relating to a machining load in at least one predetermined machining process among the machining loads in the process of machining one of the workpieces.
6. The machine tool of claim 5,
at least one of the prescribed machining processes is a roughing process,
the feature value calculation unit calculates the feature value relating to the machining load in the rough machining step.
7. The machine tool of claim 5,
at least one of the prescribed machining processes is a finishing process,
the feature value calculation unit calculates the feature value relating to the machining load in the finishing process.
8. The machine tool of claim 5,
the predetermined machining process includes both a rough machining process and a finish machining process,
the feature value calculation unit calculates the feature value relating to the machining load in the rough machining step and the feature value relating to the machining load in the finish machining step,
the relationship information is information having a correlation between the feature amount in the rough machining step, the feature amount in the finish machining step, and the surface condition of the workpiece.
9. The machine tool according to claim 1 or 2,
the machine tool further includes:
a surface condition measuring instrument that measures an actual surface condition of the workpiece selected from among a plurality of workpieces that are sequentially machined; and
and an information determination unit that determines whether or not the relationship information is good by comparing one of the workpiece index and the tool index estimated by the estimation unit with the actual surface state measured by the surface state measuring instrument.
10. The machine tool according to claim 1 or 2,
the relationship information stored in the relationship information storage unit is a learning model indicating a relationship between the machining load and the workpiece index generated by machine learning, or a learning model indicating a relationship between the machining load and the tool index generated by machine learning.
11. The machine tool of claim 10,
the learning model as the relationship information is updated based on an actual surface state of the workpiece and either one of the workpiece index and the tool index estimated by the estimating portion.
12. A machine tool is provided with:
a machining load measuring instrument that measures a machining load during machining of a workpiece by a tool;
a threshold value storage unit that stores a threshold value for correcting the surface state of the tool or replacing the tool, the threshold value being determined based on relationship information between the machining load and either one of a workpiece index indicating a surface state of the workpiece and a tool index indicating a surface state of the tool; and
and an implementation determination unit that determines whether or not the surface state of the tool can be corrected or the tool can be replaced, based on the machining load for each of the workpieces measured when the plurality of workpieces are continuously machined in sequence and the threshold stored in the threshold storage unit.
13. The machine tool of claim 12,
the machine tool further comprises a feature value calculation unit,
the feature value calculation unit calculates a feature value relating to the machining load during machining of one of the workpieces,
the relationship information is information having a correlation between the feature amount and the workpiece index or information having a correlation between the feature amount and the tool index.
14. The machine tool of claim 13,
the feature value calculation unit calculates a plurality of types of feature values related to the machining load during machining of one workpiece,
the relationship information is information having a correlation between a plurality of kinds of the feature amounts and the workpiece index, or information having a correlation between a plurality of kinds of the feature amounts and the tool index.
15. The machine tool according to claim 13 or 14,
the machine tool is further provided with a machining control unit,
the machining control unit machines one of the workpieces by the tool in a plurality of machining processes,
the feature value calculation unit calculates the feature value relating to a machining load in at least one predetermined machining process among the machining loads in the process of machining one of the workpieces.
16. The machine tool of claim 15,
at least one of the prescribed machining processes is a roughing process,
the feature value calculation unit calculates the feature value relating to the machining load in the rough machining step.
17. The machine tool of claim 15,
at least one of the prescribed machining processes is a finishing process,
the feature value calculation unit calculates the feature value relating to the machining load in the finishing process.
18. The machine tool of claim 15,
the predetermined machining process includes both a rough machining process and a finish machining process,
the feature value calculation unit calculates the feature value relating to the machining load in the rough machining step and the feature value relating to the machining load in the finish machining step,
the relationship information is information having a correlation between the feature amount in the rough machining step, the feature amount in the finish machining step, and the surface condition of the workpiece.
19. The machine tool of claim 12,
the machine tool further includes:
a surface condition measuring instrument that measures an actual surface condition of the workpiece selected from among a plurality of workpieces that are sequentially machined;
an estimating unit that estimates a surface state of the workpiece based on the machining load and the relationship information regarding the workpiece; and
and an information determination unit that determines whether the threshold value is good or bad by comparing the surface state of the workpiece estimated by the estimation unit with the actual surface state measured by the surface state measuring instrument.
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| CN114654300A (en) * | 2022-04-27 | 2022-06-24 | 湖州学院 | Combined machine tool production line |
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| JP7401207B2 (en) | 2019-06-21 | 2023-12-19 | ファナック株式会社 | Machine learning device, robot system, and machine learning method for learning tool status |
| EP3933524A1 (en) * | 2020-07-02 | 2022-01-05 | Kistler Holding AG | Method and device to ascertain a quality of a product obtained by subtractive manufacturing |
| JP6935606B1 (en) | 2021-04-05 | 2021-09-15 | Dmg森精機株式会社 | Information processing equipment and information processing programs |
| DE112021007553T5 (en) * | 2021-08-30 | 2024-05-02 | Mitsubishi Electric Corporation | Apparatus for predicting machining dimensions, system for predicting machining dimensions, method for predicting machining dimensions and program |
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