JP2018051725A - Measuring method of cutting edge position of tool and machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method of a cutting edge position of a tool and a machine tool, which can improve machining efficiency by monitoring the state of a machine body in the machining and properly setting a measurement time for the cutting edge position of the tool.SOLUTION: A measuring method of a cutting edge position of a tool captures images of a tool T mounted in a main shaft 18 and measures the cutting edge position of the tool T on the basis of the images obtained by capturing the images. In the measuring method, measurement conditions for measuring the cutting edge position of the tool T are set to four measurement conditions: a time when temperature change amount detected by temperature sensors 51 to 60 exceeds prescribed temperature change amount; a time when machining is continuously performed for more than a fixed time by only a single tool T; a time when a machining condition is changed; and a time when a measurement command is preliminarily set in a machining program. When at least any one measurement condition of the four measurement conditions is satisfied in the machining, it is determined that a deviation occurs in the cutting edge position of the tool T and the cutting edge position of the tool T is measured.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tool edge position measuring method and a machine tool that appropriately set a measurement timing for a tool edge position by monitoring a state of a machine tool during machining.

  In recent years, in the technical field of machine tools, demands for machining accuracy are increasing, and in order to meet these demands, various devices for improving machining accuracy have been provided.

  For example, in a machine tool such as a machining center, a tool such as a drill or an end mill comes into contact with a workpiece while rotating. For this reason, in order to improve machining accuracy, the state of the tool mounted on the spindle (blade edge position, blade edge shape, tool length, tool diameter, runout, etc.) is sufficiently grasped in advance before machining. It is important.

  Therefore, conventionally, some machine tools are provided with a tool measuring device that can automatically measure the state of the tool. In this tool measuring apparatus, a tool mounted on a spindle that rotates at high speed is imaged two-dimensionally, and the state of the tool is automatically measured. On the other hand, in the NC device of a machine tool, machining is performed after correcting the cutting edge position of the tool according to the measurement result by the tool measuring device.

  And as above-mentioned imaging-type tool measuring device, it is indicated by patent documents 1, for example.

JP 2006-284531 A

  Here, when the machining of the workpiece is started by the machine tool, various motors and pumps are driven to generate heat. In particular, when machining a large workpiece, since the machining is continued for a long time, the internal temperature of the machine changes greatly or the ambient temperature of the machine changes greatly due to the heat generated by the motor or pump. As a result, thermal displacement occurs in the machine tool, and as a result, the cutting edge position of the tool is shifted from a desired position, which may cause a reduction in machining accuracy.

  That is, the cutting edge position of the tool may be displaced during machining due to disturbance factors such as a change in the internal temperature of the machine tool and a change in the external temperature around the machine tool. For this reason, if only the measurement with respect to the cutting edge position of the tool is performed before machining, the cutting edge position may be displaced during machining, which may not lead to improvement in machining accuracy. However, if the measurement with respect to the cutting edge position of the tool is simply performed a plurality of times at the time of machining, the number of machining interruptions increases, leading to a reduction in machining efficiency.

  Therefore, the present invention solves the above-mentioned problem, and it is possible to improve the machining efficiency by monitoring the state of the machine body during machining and appropriately setting the measurement timing for the tool edge position. An object is to provide a tool edge position measuring method and a machine tool.

The cutting edge position measuring method for a tool according to the first invention for solving the above-mentioned problem is as follows.
In the tool edge position measuring method of imaging a tool mounted on a spindle of a machine tool and measuring the edge position of the tool based on an image obtained by the imaging,
As a measurement condition for measuring the cutting edge position of the tool,
When at least one of the temperature change amount of the machine tool and the temperature change amount around the machine tool exceeds a predetermined temperature change amount,
When machining continuously for a certain period of time only with a single tool,
When the tool changes the processing conditions for processing the workpiece,
Set four measurement conditions when a measurement command is set in advance in a machining program for the tool to machine the workpiece,
During machining, when at least one of the four measurement conditions is satisfied, it is determined that a deviation has occurred in the tool tip position, and the tool tip position is measured. To do.

The cutting edge position measuring method for a tool according to the second invention for solving the above-mentioned problems is as follows.
Even if at least one of the four measurement conditions is satisfied, it is determined from the measurement results when executing the same machining program used in the past that there is no deviation in the cutting edge position of the tool. in case of,
The imaging time for the cutting edge position of the tool is shortened, or the cutting edge position of the tool is not measured.

A cutting edge position measuring method for a tool according to a third invention for solving the above-mentioned problems is as follows.
The cutting edge position of the tool is measured after the thermal displacement of the machine tool shifts from a transition period in which the thermal displacement fluctuates to a stable period in which the thermal displacement converges.

A cutting edge position measuring method for a tool according to a fourth invention for solving the above-mentioned problems is as follows.
The imaging time in the stable period when the thermal displacement of the machine tool converges is shorter than the imaging time in the transient period when the thermal displacement of the machine tool fluctuates.

A machine tool according to a fifth invention for solving the above-described problem is
In a machine tool that processes the workpiece by the tool by relatively moving the tool and the workpiece,
A temperature sensor for detecting the temperature change amount of the aircraft and the temperature change amount around the aircraft; and
Imaging means for imaging the tool mounted on the spindle and obtaining the captured image;
Measuring means for measuring the position of the cutting edge of the tool based on the captured image captured by the imaging means;
Control for controlling the relative movement between the tool and the workpiece according to the deviation amount of the cutting edge position after obtaining the deviation amount of the cutting edge position based on the cutting edge position measured by the measuring means. With the device,
The controller is
As a measurement condition for measuring the cutting edge position of the tool,
When the temperature change amount detected by the temperature sensor exceeds a predetermined temperature change amount,
When machining continuously for a certain period of time only with a single tool,
When the tool changes the processing conditions for processing the workpiece,
The tool has four measurement conditions when a measurement command is set in advance in a machining program for machining the workpiece,
During machining, when at least one of the four measurement conditions is satisfied, it is determined that a deviation has occurred in the tool tip position, and the tool tip position is measured. To do.

  Therefore, according to the cutting edge position measuring method and machine tool of the tool according to the present invention, it is determined that a deviation has occurred in the cutting edge position of the tool when at least one of the four measurement conditions described above is satisfied. By measuring the tool edge position, the measurement time for the tool edge position during machining can be set appropriately. This eliminates the need for performing unnecessary measurement, thereby improving machining efficiency.

1 is a front perspective view of a machine tool to which a tool tip position measuring method according to an embodiment of the present invention is applied. It is a schematic block diagram of the feeder provided in the machine tool. It is a schematic block diagram of an imaging type tool measuring device. It is a control flowchart of a blade edge position measuring method.

  Hereinafter, a tool edge position measuring method and a machine tool according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a bed 11 is provided at the lower part of a machine tool 1 having a gate shape. A table 12 is supported on the upper surface of the bed 11 so as to be movable in the X-axis direction, which is the longitudinal direction of the machine. A work (workpiece) W is detachably attached to the upper surface of the table 12. Yes. A pair of left and right side beds 13a and 13b are provided on the left and right sides of the bed 11, and a column-shaped column 14 is erected on the upper surface of the side beds 13a and 13b.

  Further, a cross rail 15 is supported on the front surface of the column 14 so as to be movable in the Z-axis direction which is the vertical direction of the machine. A saddle 16 is provided in the horizontal direction of the machine at the front portion of the cross rail 15. It is supported so as to be movable in the Y-axis direction. Further, a ram 17 is pierced and supported in the saddle 16 so as to be movable in the Z-axis direction, and a main shaft 18 is supported in the ram 17 so as to be rotatable around the vertical axis (around the Z-axis). ing. A tool T is detachably attached to the tip of the main shaft 18.

  As described above, the table 12, the cross rail 15, the saddle 16, and the ram 17 are moving bodies that reciprocate linearly. However, as shown in FIG. The feeding device 20 is connected to 16 and 17, respectively. In this way, by individually connecting the feeding device 20 to the table 12, the cross rail 15, the saddle 16, and the ram 17, the movable bodies 12, 15, 16, and 17 are reciprocated linearly in the respective axial directions. It is movable.

  As shown in FIG. 2, the feeding device 20 includes a servo motor 21, a reduction gear 22, a ball screw shaft 23, a ball screw nut 24, and the like. The servo motor 21 is connected to one end of the ball screw shaft 23 through a plurality of reduction gears 22. A ball screw nut 24 is screwed onto the ball screw shaft 23, and the table 12, the cross rail 15, the saddle 16, and the ram 17 are joined to the ball screw nut 24.

  As shown in FIG. 1, the machine tool 1 is provided with a cooling pipe 31. The cooling pipe 31 circulates and supplies coolant for cooling the machine tool 1. For example, the cooling pipe 31 is provided inside the table 12, column 14, cross rail 15, saddle 16, ram 17, main shaft 18, and the like. By passing, they can be cooled. And the cooler 31 is provided with the cooler 32, and this cooler 32 can hold | maintain the temperature of the coolant which passed the said cooler 32 below to predetermined temperature.

  Further, the machine tool 1 is provided with a lubricating oil supply pipe 41. The lubricating oil supply pipe 41 circulates and supplies lubricating oil to each sliding surface in the machine tool 1. For example, a bearing surface of a bearing that rotatably supports the main shaft 18 or the table 12. After the lubricating oil is supplied to the sliding surfaces of the cross rail 15, the saddle 16 and the ram 17, the lubricating oil after this lubrication can be recovered. The lubricant supply pipe 41 is provided with a cooler 42. The cooler 42 can keep the temperature of the lubricant that has passed through the cooler 42 below a predetermined temperature.

  Here, as shown in FIGS. 1 and 2, the machine tool 1 is provided with a plurality of temperature sensors 51 to 60 for monitoring temperature changes of the machine body and temperature changes around the machine body. Such temperature sensors 51 to 60 are used not only for the main structure of the machine tool 1, the main shaft 18 serving as a heat source and various motors, but also for a flow path for flowing fluid such as coolant, lubricating oil, hydraulic oil, and the like. Is provided. Specific examples of the installation positions of the temperature sensors 51 to 60 will be described below.

  First, as shown in FIG. 1, the body temperature sensors 51 to 55 are provided on the table 12, the column 14, the cross rail 15, the saddle 16, and the ram 17 which are main structures. These body temperature sensors 51 to 55 detect the temperatures (temperature change amounts) of the table 12, the column 14, the cross rail 15, the saddle 16, and the ram 17, and the detected body temperature is an NC device to be described later. 80 can be output.

  On the other hand, an air temperature sensor 56 is provided outside the machine tool 1. The air temperature sensor 56 can detect the outside air temperature (the amount of change in the outside air temperature) around the machine tool 1 and output the detected outside air temperature to the NC device 80.

  Next, as shown in FIGS. 1 and 2, the main shaft 18 and the servo motor 21 serving as a heat source are provided with heat source temperature sensors 57 and 58. These heat source temperature sensors 57 and 58 can detect the temperature (temperature change amount) of the main shaft 18 and the servo motor 21 and output the detected heat source temperature to the NC device 80. Note that the heat source of the machine tool 1 may be a pump for flowing the fluid, a bearing that rotatably supports a rotating body such as the main shaft 18, and the like. May be installed.

  Finally, as shown in FIG. 1, fluid temperature sensors 59 and 60 are provided in the cooling pipe 31 and the lubricating oil supply pipe 41 for flowing fluid toward the inside of the machine tool 1. The fluid temperature sensor 59 can detect the coolant temperature (temperature change amount) and output the detected fluid temperature to the NC device 80. The fluid temperature sensor 59 can output the detected fluid temperature to the inlet side (return side) and the outlet side (supply) of the cooler 32. Are arranged on both sides). Similarly, the fluid temperature sensor 60 can detect the temperature (temperature change amount) of the lubricating oil, and can output the detected fluid temperature to the NC device 80. It is arranged on both the outlet side (supply side).

  As shown in FIGS. 1 and 3, an imaging-type tool measuring device 70 is provided at the top corner of the table 12. The tool measuring device 70 automatically measures the blade tip position (three-dimensional coordinates) of the tool T by performing image processing on an image obtained by imaging the tip of the tool T. For example, a base 71, a light source 72, a CCD camera (imaging unit) 73, and a measurement processing unit (measurement unit) 74 are provided.

  Specifically, a light source 72 and a CCD camera 73 are supported on a base 71 provided on the upper surface of the table 12 so as to face each other in the XY plane. The light source 72 can output parallel light toward the light receiving surface of the CCD camera 73. On the other hand, the CCD camera 73 can continuously capture the tip of the tool T at regular time intervals and output an image obtained by the imaging to the measurement processing unit 74 as an image signal. It has become. The measurement processing unit 74 performs image processing on the image signal supplied from the CCD camera 73 to generate image data, and then measures the cutting edge position of the tool T based on the image data. This can be output to the NC device 80. A high-power lens (not shown) is attached to the light receiving surface of the CCD camera 73.

  Further, as shown in FIG. 1, the machine tool 1 is provided with an NC device (control device) 80 that integrally controls the entire operation of the machine tool 1. The control device 80 includes, for example, each servo motor 21 corresponding to the table 12, the cross rail 15, the saddle 16, and the ram 17, a motor (not shown) for rotating the spindle 18, and each sensor 51-60. The light source 72 of the tool measuring device 70, the CCD camera 73, the measurement processing unit 74, and the like are electrically connected.

  That is, when machining the workpiece W, by controlling the drive of each servo motor 21, the tool T mounted on the spindle 18 and the workpiece W mounted on the table 12 are moved in the X-axis direction, Y It is moved relatively in the axial direction and the Z-axis direction. Thereby, the cutting edge of the tool T rotating at high speed comes into contact with a predetermined machining point on the workpiece W based on a preset machining program, and the workpiece W is machined into a desired shape.

  In addition, the NC device 80 drives the tool measuring device 70 before the workpiece W is processed and during the processing of the workpiece W (during the processing), and performs automatic measurement on the cutting edge position of the tool T. Among these, when machining the workpiece W, the state of the machine tool 1 (for example, whether there is a temperature change, whether there is a tool change, whether there is a change in machining conditions, whether there is an automatic measurement command in the machining program, etc.) is constantly monitored. When the state is monitored and it is determined that a deviation has occurred in the blade tip position of the tool T, automatic measurement for the blade tip position of the tool T is immediately performed.

  At this time, the following four measurement conditions are set as measurement conditions for measuring the cutting edge position of the tool T at the time of machining. That is, the four measurement conditions are conditions that may cause a deviation with respect to the cutting edge position of the tool T during machining. Thus, automatic measurement is performed when at least one of the four measurement conditions is satisfied.

Four measurement conditions at the time of processing are (1) to (4) shown below.
(1) When at least one of the temperature change amount of the machine tool 1 and the temperature change amount around the machine tool 1 exceeds a predetermined temperature change amount. Specifically, the amount of temperature change detected by the body temperature sensors 51 to 55, the amount of temperature change detected by the air temperature sensor 56, the amount of temperature change detected by the heat source temperature sensors 57 and 58, and the fluid temperature sensor 59 , 60, at least one of the temperature change amounts exceeds a threshold value.
(2) When machining is performed continuously for a predetermined time or more with only a single tool T mounted on the spindle 18 without changing tools.
(3) When machining conditions such as the rotational speed of the spindle 18 and the feed speed of the tool T (spindle 18) are changed. In other words, the machining conditions are changed, and measurement is performed immediately before machining under the changed machining conditions.
(4) When a measurement command is set in advance in the machining program. That is, in the machining program, a measurement command is set in advance corresponding to a point in time when there is a possibility that the cutting edge position of the tool T is displaced.

  From the above, when automatically measuring the cutting edge position of the tool T, first, as shown in FIG. 3, the rotated spindle 18 is positioned at the reference position set above the tool measuring device 70, The tip of the tool T mounted on the main shaft 18 is caused to enter a measurement position set between the light source 72 and the CCD camera 73. The measurement position refers to the rotation axis (center axis) of the main shaft 18 and the tool T and the image vertical center line of the CCD camera 73, and the tip where the blade edge is formed is within the field of view of the CCD camera 73. It is a position that fits in.

  Next, the light source 72 is driven to irradiate parallel light toward the tip of the tool T. As a result, an image (outline, shadow, outline) at the tip of the tool T with the parallel light as a backlight is formed on the light receiving surface of the CCD camera 73. Subsequently, the CCD camera 73 sends an image signal corresponding to the image formed on the light receiving surface to the measurement processing unit 74.

  In the measurement processing unit 74, after the image signal supplied from the CCD camera 73 is converted into image data of a predetermined format, the cutting edge position of the tool T is calculated based on the image data, and this is converted into the NC device. Send to 80. Finally, in the NC device 80, after comparing the cutting edge position supplied from the measurement processing unit 74 with a preset reference cutting edge position and obtaining the deviation amount of the cutting edge position in the imaged tool T, The relative movement between the tool T and the workpiece W is controlled in accordance with the amount of deviation of the cutting edge position.

  Next, the flow of the automatic measurement process for the cutting edge position of the tool T will be described with reference to FIG.

  First, in step S1, before machining the workpiece W, the cutting edge position of the tool T is measured to determine the amount of deviation.

  Next, in step S2, the workpiece W is machined while correcting the relative movement between the tool T and the workpiece W in accordance with the deviation amount of the cutting edge position obtained in step S1. In step S1, when there is no deviation amount of the blade edge position, the workpiece W is processed without correcting the relative movement between the tool T and the workpiece W.

  Then, in step S3, it is determined whether or not measurement for the cutting edge position at the time of machining is necessary. That is, it is determined whether at least one of the measurement conditions (1) to (4) described above is satisfied.

  If yes, in step S4, the cutting edge position of the tool T at the time of machining is measured, and the amount of deviation is obtained. Next, in step S5, the workpiece W is machined while correcting the relative movement between the tool T and the workpiece W in accordance with the deviation amount of the cutting edge position obtained in step S4. And it returns to step S3 and a process is continued.

  On the other hand, if no, in step S6, the machining of the workpiece W is continued as it is without measuring the cutting edge position of the tool T at the time of machining. And it returns to step S3 and a process is continued.

  In the above-described embodiment, the measurement at the time of machining is performed when at least one of the measurement conditions (1) to (4) is satisfied. Even if one measurement condition is satisfied, if it is determined from the measurement results when executing the same machining program used in the past that there is no deviation in the cutting edge position of the tool T, the imaging time by the CCD camera 73 is shortened. Or measurement of the cutting edge position of the tool T may be stopped.

  In addition, by providing the temperature sensors 51 to 60, not only can the temperature sensors 51 to 60 detect each temperature change amount corresponding to them, but also how the detected temperature changes with time. Can predict. That is, it is possible to predict how the thermal displacement of each part where the temperature sensors 51 to 60 are installed will change over time.

  Thereby, when measuring at the time of a process, you may make it measure after the thermal displacement of the machine tool 1 transfers from the transition period when a thermal displacement fluctuates to the stable period when a thermal displacement converges. Absent. That is, the measurement accuracy can be improved by measuring the cutting edge position of the tool T after waiting for the thermal displacement of the machine tool 1 to converge.

  Furthermore, even during measurement, the thermal displacement of the machine tool 1 may be in a transition period or may be in a stable period. In such a case, the imaging time in the thermal displacement stable period may be shorter than the imaging time in the thermal displacement transient period. Thereby, the total time required for measurement can be shortened.

  Furthermore, in addition to the temperature sensors 51 to 60, a thermographic sensor that can directly detect the temperature change amount of the tool T may be provided. Thereby, the necessity of the measurement with respect to the blade edge position can be determined more accurately.

  Therefore, according to the present invention, a condition that may cause a deviation with respect to the cutting edge position of the tool T at the time of machining is set as a plurality of measurement conditions at the time of machining, and one of the measurement conditions is satisfied. First, it is determined that a deviation has occurred in the cutting edge position of the tool T, and the cutting edge position of the tool T is measured. Thereby, the measurement time with respect to the cutting edge position of the tool T at the time of a process can be set appropriately. Therefore, it is not necessary to perform unnecessary measurement, so that the processing efficiency can be improved.

DESCRIPTION OF SYMBOLS 1 Machine tool 11 Bed 12 Table 14 Column 15 Cross rail 16 Saddle 17 Ram 18 Main shaft 20 Feeder 21 Servo motor 31 Cooling pipe 41 Lubricating oil supply pipe 51-55 Airframe temperature sensor 56 Air temperature sensor 57, 58 Heat source temperature sensor 59, 60 Fluid Temperature Sensor 70 Tool Measuring Device 73 CCD Camera 74 Measurement Processing Unit 80 NC Device T Tool W Workpiece

Claims (5)

In the tool edge position measuring method of imaging a tool mounted on a spindle of a machine tool and measuring the edge position of the tool based on an image obtained by the imaging,
As a measurement condition for measuring the cutting edge position of the tool,
When at least one of the temperature change amount of the machine tool and the temperature change amount around the machine tool exceeds a predetermined temperature change amount,
When machining continuously for a certain period of time only with a single tool,
When the tool changes the processing conditions for processing the workpiece,
Set four measurement conditions when a measurement command is set in advance in a machining program for the tool to machine the workpiece,
During machining, when at least one of the four measurement conditions is satisfied, it is determined that a deviation has occurred in the tool tip position, and the tool tip position is measured. Of measuring the position of the cutting edge of the tool to be used. In the cutting edge position measuring method of the tool according to claim 1,
Even if at least one of the four measurement conditions is satisfied, it is determined from the measurement results when executing the same machining program used in the past that there is no deviation in the cutting edge position of the tool. in case of,
The method for measuring the edge position of a tool, wherein the imaging time for the edge position of the tool is shortened or the edge position of the tool is not measured. In the cutting edge position measuring method of the tool according to claim 1 or 2,
The tool tip position measuring method, wherein the tool tip position is measured after the thermal displacement of the machine tool shifts from a transition period in which the thermal displacement fluctuates to a stable period in which the thermal displacement converges. In the cutting edge position measuring method of the tool according to claim 1 or 2,
The tool edge position measuring method, wherein an imaging time in a stable period when the thermal displacement of the machine tool converges is shorter than an imaging time in a transient period in which the thermal displacement of the machine tool fluctuates. In a machine tool that processes the workpiece by the tool by relatively moving the tool and the workpiece,
A temperature sensor for detecting the temperature change amount of the aircraft and the temperature change amount around the aircraft; and
Imaging means for imaging the tool mounted on the spindle and obtaining the captured image;
Measuring means for measuring the position of the cutting edge of the tool based on the captured image captured by the imaging means;
Control for controlling the relative movement between the tool and the workpiece according to the deviation amount of the cutting edge position after obtaining the deviation amount of the cutting edge position based on the cutting edge position measured by the measuring means. With the device,
The controller is
As a measurement condition for measuring the cutting edge position of the tool,
When the temperature change amount detected by the temperature sensor exceeds a predetermined temperature change amount,
When machining continuously for a certain period of time only with a single tool,
When the tool changes the processing conditions for processing the workpiece,
The tool has four measurement conditions when a measurement command is set in advance in a machining program for machining the workpiece,
During machining, when at least one of the four measurement conditions is satisfied, it is determined that a deviation has occurred in the tool tip position, and the tool tip position is measured. Machine tool to do.

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