JP2012213840A - Machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machine tool capable of measuring a distance between a reference part of a tool support body and a tip of a tool and improving machining dimensional accuracy.SOLUTION: The machine tool includes a work support body such as a spindle 6 and the tool support body such as a tool rest 7 to perform cutting by relatively moving both the work support body and the tool support body. The machine tool includes a measurement means 61 between a cutting edge and the reference part for measuring a distance L3 between the reference part 7s of the tool rest 7 along the relatively moving direction (X-axis direction) and a tool tip 18t. The measurement means 61 between the cutting edge and the reference part includes an imaging device 62 capable of simultaneously photographing the reference part 7s and the tool tip 18t, and an image processing means 63 for processing images simultaneously photographed by the imaging device 64 to calculate the distance L3, for instance. Two imaging devices 62 may be used for separately detecting the reference part 7s and the tool tip 18t or one imaging device may be used for detecting them by being moved.

Description

  The present invention relates to a machine tool such as a lathe, a drill, and a grinder, and more particularly to a machine tool having a measurement function for guaranteeing the reproducibility of the position of a cutting edge when changing tools, correcting a thermal displacement, and the like.

  In a machine tool such as a lathe, thermal expansion and thermal deformation of a bed and other parts occur due to cutting heat and heat generated by each part accompanying machine operation. Such thermal expansion and thermal deformation lead to a decrease in processing accuracy. Some of them are equipped with a cooling device as a countermeasure. However, in order to sufficiently suppress the thermal expansion, the cooling device becomes large, and the processing accuracy cannot be ensured only by cooling. Therefore, various types have been proposed in the past for measuring thermal expansion and correcting thermal displacement such as the cutting depth of a tool (for example, Patent Documents 1 and 2).

  Conventionally, as a technique for guaranteeing the reproducibility of the cutting edge position in the tool change, a technique for managing from a processing dimension by trial machining or a technique for managing a cutting edge position by providing a cutting edge detector such as a touch sensor is used. (For example, patent document 3).

JP 2002-144191 A Japanese Patent No. 2706420 Japanese Patent No. 3577887

As a technique for correcting the thermal displacement such as the cutting depth of the tool, by measuring the distance between the center of the spindle supporting the workpiece and the reference part of the tool mounting on the tool support individually, the center of the spindle and the tool are measured. The distance between the reference portions of the support was obtained with high accuracy, and a device capable of highly accurate thermal displacement correction was proposed (for example, Japanese Patent Application No. 2009-251736).
However, in this proposed example, the distance between the center of the spindle and the reference of the tool support is accurately measured, but the change in the cutting edge position of the tool with respect to the reference portion of the tool support is not taken into consideration. For this reason, the reproducibility of the cutting edge position when the tool is changed is not guaranteed, which is insufficient for improving the machining accuracy.

  In trial machining, which is a conventional method that guarantees reproducibility of the cutting edge position in tool change, work time is required for trial machining, measurement after machining, and input of correction values according to the measurement results, reducing the operating rate. Invite. In the conventional blade edge detector, a touch sensor is provided on the swivel arm installed on the machine body cover, etc., so it is difficult to realize accuracy in the order of μm mechanically from the point of reproducibility, and the attachment of the tool type Only error detection and rough location management can be performed.

An object of the present invention is to provide a machine tool that can measure a distance between a reference portion of a tool support and a tip of a tool and can improve machining dimensional accuracy.
Another object of the present invention is to measure the distance between the reference portion of the tool support and the tip of the tool with higher accuracy.
Still another object of the present invention is to provide a machine tool capable of measuring a distance between a reference portion of a tool support and a tip of a tool with a simple configuration.
Still another object of the present invention is to provide a machine tool capable of further improving machining dimensional accuracy.

  The machine tool of the present invention includes a workpiece support (6) that supports the workpiece (W), and a tool support (7) that supports the tool (18) by attaching the tool (18) to a predetermined reference portion (7s). A machine tool for cutting a workpiece by moving the workpiece support (6) and the tool support (7) relative to each other and bringing the tip (18t) of the tool (18) into contact with the workpiece (W). Cutting edge / reference portion measuring means (61, 61A) for measuring the distance between the reference portion (7s) of the tool support (7) and the tip (18t) of the tool along the relative movement direction (X-axis direction). , 61B, 61C). The reference portion (7s) is, for example, a surface facing the relative movement direction of the tool support (7), or a point or a portion.

  According to this structure, the measuring means (61, 61A, 61B, 61C) between the blade tip and the reference part for measuring the distance (L3) between the reference part (7s) of the tool support (7) and the tip (18t) of the tool. Therefore, even if there is a change in the mounting position of the tool (18) with respect to the tool support (7) due to tool replacement, the distance between the reference portion (7s) of the tool support (7) and the tip (18t) of the tool ( L3) can be recognized by actual measurement. Therefore, the tool tip (18t) position can be managed with high accuracy, and the processing dimension accuracy can be improved.

In the present invention, the measuring means (61) between the cutting edge and the reference part includes an imaging device (62) capable of simultaneously photographing the reference part (7s) and the tip (18t) of the tool, and the imaging device (62). Image processing means (63) for processing an image including the reference portion (7s) and the tip (18t) of the tool, which are simultaneously photographed, and calculating a distance (L3) between the reference portion and the tip (18t) of the tool; It may be made up of.
In the case of this configuration, since the reference portion (7s) and the tip (18t) of the tool (18) are simultaneously photographed, by the image processing, the distance between the reference portion (7s) and the tip (18t) of the tool (18) is obtained. Can be calculated with high accuracy.

In the present invention, the measuring means (61A) between the cutting edge and the reference portion is provided with two image pickup devices (62 ₁ , 62 ₂ ) that respectively photograph the reference portion (7s) and the tip (18t) of the tool (18). Then, the two images obtained by these two imaging devices (62 ₁ , 62 ₂ ) are processed, respectively, and the reference portion (7s) and the tip of the tool (18) with respect to the reference position in each image ( 18t), the image processing means (63A) for obtaining the coordinate position, the reference position (7s) obtained by the image processing means (63A) and the coordinate position of the tip (18t) of the tool (18), Image processing result synthesis means (65) for calculating a distance (L3) between the reference portion (7s) and the tip (18t) of the tool from data of an actual distance (LX) between the reference positions of two images Even as There. The above-mentioned “actual distance (LX)” and “actual” of a certain part mean that it is not a distance on the image.
In the case where the reference portion (7s) and the tip (18t) of the tool (18) are simultaneously photographed, since a wide range of imaging is performed, the distance (L3) between the reference portion (7s) and the tool tip (18t). In order to obtain the image quality with high accuracy, it is necessary to increase the number of pixels of the imaging device, and the processing data amount of the image processing increases, which takes time. However, as described above, by separately imaging the reference portion (7s) and the tool tip (18t) with the _two imaging devices (62 ₁ , 62 ₂ ), imaging in a narrow range is sufficient, and the imaging device (62 ₁ and 62 ₂ ), the distance (L3) between the reference portion and the tool tip (18t) can be obtained with high accuracy even if the number of pixels is small. In addition, the amount of processing data for image processing is small, and measurement can be performed quickly. Therefore, highly accurate measurement can be performed quickly.

In the present invention, the measuring means (61B) between the cutting edge and the reference part is arranged such that the reference part (7s) and the tip (18t) of the tool (18) are connected to the reference part (7s) and the tip of the tool (18) ( 18t) moving in the separation direction (X-axis direction) and individually capturing images, the image of the reference portion (7s) captured individually and the tip of the tool (18) (18t) The image processing means (63B) for processing the respective images) to obtain the coordinate position of the reference portion and the tip of the tool (18t) with respect to the reference position in each image, and the image processing means (63B) The distance between the reference portion and the tip of the tool (18t) is determined from the obtained coordinate position of the reference portion (7s) and the tip (18t) of the tool (18) and the data of the moving distance of the imaging device. Calculation That the image processing result combining unit may be made out with (65B).
Even in this configuration, by separately capturing the reference portion (7s) and the tool tip (18t), it is sufficient to capture a narrow range, and even if the number of pixels of the image pickup device (62B) is small, the reference portion ( 7s) and the distance (L3) between the tool tip (18t) can be obtained. In addition, the amount of processing data for image processing is small, and the calculation processing time can be shortened even if the capability of the image processing means (63B) is low.

In the present invention, the blade tip / reference portion measuring means (61C) includes one contact sensor (67) for detecting a position by contact, the reference portion (7s) measured by the contact sensor (67), and The distance calculation means (68) for obtaining the distance (L3) between the reference portion (7s) and the tip (18t) of the tool (18) from the difference in the detected value of the position of the tip (18t) of the tool (18). It may be.
When the contact type sensor (67) is used, an operation time for measurement is required, but the measuring means (61C) between the cutting edge and the reference portion can be simply configured.

In this invention, between the workpiece support side reference position (O) which is the reference position for supporting the workpiece (W) of the workpiece support (6) and the reference portion (7s) of the tool support (7). An inter-reference distance measuring means (29) for measuring the distance (L4) may be provided.
When the distance (L4) between the workpiece support side reference position (O) and the reference portion (7s) of the tool support (7) is measured by providing the inter-reference distance measurement means (29), the cutting edge The workpiece support side reference position is obtained by subtracting the distance between the reference portion (7s) of the tool support (7) and the tool tip (18t) measured by the measurement means (61, 61A, 61B, 61C) between the reference portions. The distance between (O) and the tip (18t) position of the tool (18) is known. The distance (L3) between the workpiece support side reference position (O) and the tip (18t) position of the tool (18) corresponds to the post-working dimension of the work, and actually measures the working diameter of the work. It will be possible. Therefore, the processing dimensional accuracy can be improved with higher accuracy.

  A machine tool according to the present invention includes a workpiece support that supports a workpiece, and a tool support that supports a tool by attaching the tool to a predetermined reference portion, and moves the workpiece support and the tool support relative to each other. A machine tool for cutting a workpiece by bringing the tip of a tool into contact with the tool, and measuring a distance between the reference portion of the tool support and the tip of the tool along the relative movement direction. Since the measuring means is provided, the distance between the reference portion of the tool support and the tip of the tool can be measured, and the machining dimensional accuracy can be improved.

  The cutting edge-to-reference portion measuring means processes an image including the reference portion and the tip of the tool simultaneously captured by the imaging device capable of simultaneously photographing the reference portion and the tip of the tool, and In the case of the image processing means that calculates the distance between the reference portion and the tip of the tool, the distance between the reference portion of the tool support and the tip of the tool can be accurately measured.

  The measuring means between the cutting edge and the reference part respectively processes two images obtained by the two imaging devices that respectively photograph the reference part and the tip of the tool, and processes each of the images. Image processing means for obtaining the coordinate position of the reference portion and the tip of the tool with respect to the reference position at the reference position, the coordinate position of the reference portion and the tip of the tool obtained by the image processing means, and the two images of the two images Even in the case of the image processing result composition means for calculating the distance between the reference portion and the tip of the tool from the data of the actual distance between the reference positions, the distance between the reference portion of the tool support and the tip of the tool is also included. Can be accurately measured.

  The measuring means between the cutting edge and the reference part moves the reference part and the tip of the tool in the separating direction of the reference part and the tip of the tool, respectively, and an image pickup device that individually picks up the image. An image processing means for processing the image of the reference portion and the image of the tip of the tool to obtain the coordinate position of the reference portion and the tip of the tool with respect to the reference position in each image, and the image processing means Even when the reference position and the coordinate position of the tip of the tool, and the image processing result synthesis means for calculating the distance between the reference portion and the tip of the tool from the data of the moving distance of the imaging device, The distance between the reference portion of the tool support and the tip of the tool can be accurately measured.

  From the difference in the detected value of the position of the tip of the tool and the reference part measured by the contact sensor, the reference part measured by the contact type sensor, the reference part And a distance calculation means for determining the distance between the tool tips, the distance between the reference portion of the tool support and the tool tip can be measured with a simple configuration.

  When the inter-reference distance measuring means for measuring the distance between the work support side reference position which is the reference position for supporting the work of the work support and the reference portion of the tool support is provided, actual machining The distance between the workpiece support side reference position as the dimension and the tip of the tool can be obtained with high accuracy, and the accuracy of the machining dimension can be further improved.

It is explanatory drawing which combined the top view of the machine tool main body in the machine tool which concerns on 1st Embodiment of this invention, and the block diagram of the conceptual structure of a control apparatus. It is a perspective view of the machine tool main body. It is a fragmentary top view which shows processing operation of the machine tool. It is a front view of the headstock part of the machine tool. It is explanatory drawing of the image of the imaging device of the machine tool. It is explanatory drawing which combined the top view of the machine tool main body in the machine tool which concerns on other embodiment, and the block diagram of the conceptual structure of a control apparatus. It is explanatory drawing of the image of the imaging device of the machine tool. It is explanatory drawing which combined the top view of the machine tool main body in the machine tool which concerns on other embodiment, and the block diagram of the conceptual structure of a control apparatus. It is explanatory drawing which combined the top view of the machine tool main body in the machine tool which concerns on other embodiment, and the block diagram of the conceptual structure of a control apparatus. It is explanatory drawing which detailed the explanatory drawing of FIG. It is explanatory drawing of measurement operation | movement of the machine tool.

  A first embodiment of the present invention will be described with reference to FIGS. 1 to 5 and FIG. This machine tool includes a main shaft 6 that is a work support that supports a work W, and a tool rest 7 that is a tool support that supports a tool 18 by attaching it to a predetermined reference portion 7s. Is a machine tool that performs cutting on the workpiece W by bringing the tip 18t of the tool 18 into contact with the workpiece W. Provided is a blade tip / reference portion measuring means 61 for measuring a distance L3 (measurement target dimension) between the reference portion 7s of the tool post 7 and the tip 18t of the tool 18 along the relative movement direction (X-axis direction). Yes. Further, a reference distance for measuring a distance L4 between a workpiece support side reference position (in this example, the spindle axis O) which is a reference position for supporting the workpiece W of the spindle 6 and the reference portion 7s of the tool post 7. Measuring means 29 is provided. This will be specifically described below.

  This machine tool is a numerically controlled machine tool, and includes a machine tool body 1 that is a machine part and a control device 2 that controls the machine tool body 1. The machine tool main body 1 is a main spindle moving type lathe, and a main spindle 6 is rotatably supported on a main spindle base 5 installed on a bed 3 via a feed base 4, and a tool post 7 is provided on the bed 3. It is installed via a support base 26. The support base 26 is fixedly installed on the bed 3. The tool post 7 is formed of a turret and is supported on the support base 26 so as to be capable of rotational indexing.

  As shown in FIG. 2, the feed base 4 is movable on the X-axis guide 9 provided on the bed 3 in a horizontal main shaft radial direction (X-axis direction) orthogonal to the axis O of the main shaft 6. It is installed and driven forward and backward by an X-axis moving mechanism 12 comprising a motor 10 such as a servo motor installed on the bed 3 and a feed screw mechanism 11 for converting the rotation output into a linear motion. The feed screw mechanism 11 includes a screw shaft and a nut.

  As shown in FIG. 4, the headstock 5 is installed on a Z-axis guide 13 provided on the feed base 4 so as to be movable in the spindle axis direction (Z-axis direction), and is a motor installed on the feed base 4. 14 and a Z-axis moving mechanism 16 comprising a feed screw mechanism 15 that converts the rotation output into a linear motion, and is driven forward and backward. The feed screw mechanism 15 includes a screw shaft and a nut. The spindle 6 is rotationally driven by a spindle motor (not shown) built in the spindle stock 5. A chuck 17 is detachably provided at the front end of the main shaft 6. The chuck 17 can grip the workpiece W by a plurality of chuck claws 17a that move in the chuck radial direction.

In FIG. 2, the tool post 7 is rotatable around a horizontal rotation center T along the X-axis direction with respect to the support base 26, and a tool is provided at a plurality of circumferential positions on the front outer periphery called a turret face or the like. A tool 18 such as a cutting tool or a rotary tool is attached via the holder 18a. The outer peripheral portion of the front surface of the tool post 7 is the predetermined reference portion 7s to which the tool 18 is attached. In each figure, only one tool 18 attached to the tool post 7 is shown, and the others are not shown. The tool post 7 may have a front shape of a circle as illustrated or a polygon.
The tool post 7 is fixed to the tip of a hollow shaft 7c rotatably supported by a support base 26 via a bearing 8 (see FIG. 10), and the hollow shaft 7c is attached by an indexing motor (not shown). By rotating, an arbitrary tool 18 is turned and indexed to a position facing the main shaft 6.

  In FIG. 1, the measuring means 61 between the cutting edge and the reference part measures the distance L3 (measurement target dimension) between the reference part 7s composed of the turret face of the tool post 7 and the tip 18t of the tool 18 as described above. An image pickup device 62 capable of simultaneously shooting the reference portion 7s and the tool tip 18t, and processing the image including the reference portion 7s and the tool tip 18t simultaneously shot by the image pickup device 62 to process the reference portion 7s. And image processing means 63 for calculating a distance L3 between the tool tip 18t.

  The reference part 7s of the tool post 7 may be directly imaged by the imaging device 62, but in this embodiment, the detected member 7S is provided on the reference part 7s of the tool post 7 so that image processing is easy. The back surface of the detected member 7S is positioned on the same plane as the turret face that becomes the reference portion 7s. Specifically, the imaging device 62 images the detected member 7S, and performs image processing and calculation of the distance L3 assuming that the back surface position of the detected member 7S is the reference portion 7s. In the following description, even when the detected member 7S is imaged, it will be described as simply imaging the reference portion 7s.

  The imaging device 62 is composed of a CCD camera or the like using a solid-state imaging device, and is attached to the side surface of the headstock 5 via the attachment member 64 so as to face forward in the Z-axis direction. The imaging apparatus of each embodiment described later has the same configuration. The imaging device 62 may be installed on the bed 3 or the like as long as the reference portion 7s and the tool tip 18t can be simultaneously photographed.

  The image processing unit 63 is provided as a part of the control device 2, but may be an image processing device independent of the control device 2. For example, as conceptually shown in FIG. 5 as an example of the image G, the image processing means 63 extracts the tool tip 18t and the reference portion 7s (the code for the image is the code of the actual object) in the image G, the feature point extraction, etc. The actual distance L3 in the X-axis direction between the tool tip 18t and the reference portion 7s is obtained by comparing the distance on the image G and the actual distance using known data. The known data may be, for example, a set magnification, and may be the position of the imaging device 62 or the origin of the imaging device 62 and the center of the image G (in other words, the origin of the imaging area) GP. It may be a distance in the Z-axis direction. When a straight line connecting the imaging device 62 and the origin GP of the imaging area is inclined in the Z-axis direction, a correction value corrected using the inclination angle is used. When the imaging device 62 is installed on a movable object such as the headstock 5 or the like, the position of the movable object is always imaged as the same position. If the positional relationship between the position of the imaging device 62 and the reference unit 7s when performing each imaging is the same, the above magnification is determined.

  1, the inter-reference distance measuring means 29 measures the distance L4 between the workpiece support side reference position (in this example, the spindle axis O) and the reference portion 7s of the tool post 7 as described above. In this example, however, the spindle-side position measuring means 20 for measuring the position of the spindle axis O, the tool-side position measuring means 30 for measuring the position of the reference portion 7 s of the tool rest 7, and both measuring means 20. , 30 and the calculation means 40 for calculating the distance L4. The calculation means 40 has a function of calculating a distance L in the X-axis direction between the spindle axis O and the tool tip 18t from the calculated distance L4 and the distance L3 calculated by image processing. Specific examples of the spindle-side position measuring unit 20 and the tool post-side position measuring unit 30 will be described later with reference to FIG.

  The distance that needs to be recognized for machining is the diameter of the workpiece W after completion of machining or during machining, and this diameter is the distance L in the X-axis direction between the spindle axis O and the tool tip 18t. It is. Since it is difficult to directly measure this distance, the distances L3 and L4 are measured to determine the distance L.

  In FIG. 1, the control device 2 is formed of a computer-type numerical control device, decodes and executes each command of the machining program 41 by the arithmetic control unit 42, and gives a control command to each drive source of the machine tool body 1. The movement command 41a in the X-axis direction of the machining program 41 is a command for relatively moving the tool post 7 in the X-axis direction to the position of the command value indicating the movement destination. The arithmetic control unit 42 causes the X-axis motor 10 to move. Is output as a command to drive the.

  The calculation control unit 42 includes a thermal displacement correction unit 43, and a command value to be output to the motor 10 is calculated by the calculation unit 40 with respect to the command value of the movement command 41 a in the X-axis direction in the machining program 41. Correction is performed using the relative distance L between the spindle axis and the cutting edge. For example, when the relative distance L between the spindle axis and the cutting edge is input from the calculation unit 40, the thermal displacement correction unit 43 always stores the value until the value is updated, and corrects it using the stored value. It is supposed to do. In this case, when the spindle-side position measuring unit 20 and the cutter-side position measuring unit 30 measure the position, and the value of the relative distance L between the spindle axis and the cutting edge calculated by the calculating unit 40 is updated, the heat to be performed thereafter. The correction amount of the displacement correction means 43 changes. The correction amount by the thermal displacement correction unit 43 will be described later.

The thermal displacement correction means 43 executes the X-axis movement command 41a of the machining program 41 by the calculation control unit 42 according to the relative distance L between the spindle center and the cutting edge stored in the calculation means 40 or the thermal displacement correction means 43. When machining as shown in FIG. 3, the command value of the X-axis movement command 41a is corrected. This correction is, for example, correction for adding the difference between the spindle axis / cutting edge relative distance L and the design dimension to the command value. The thermal displacement correction means 43 has, for example, a relational setting means such as an arithmetic expression or a table for determining a correction amount for the calculation result of the calculation means 40, and the correction amount determined by using this means is used to determine the correction amount. The command value may be corrected. The relationship set by the relationship setting means may be a relationship such as a correction amount for the difference between the distance obtained by the calculation means 40 and the command value based on the actual driving result or the like. Thus, by correcting by the thermal displacement correction means 43, it can correct with a sufficient precision corresponding to a thermal displacement, and processing precision improves.
In addition, an appropriate thermal displacement correction | amendment can be performed by measuring for every set time or every set time, such as every other hour, for example, and updating the calculation result of the calculating means 40 within one day.

The operation of the above configuration will be described. The distance L4 between the spindle axis O and the reference portion 7s of the tool post 7 is measured by the inter-reference distance measuring means 29, but the tool length is calculated as known only by measuring this distance L4. The distance L between the spindle axis O necessary for control and the tool tip 18t cannot be obtained with high accuracy. If an error occurs in the mounting position of the tool 18 with respect to the tool post 7 due to the tool change, the error becomes a machining error.
On the other hand, in this embodiment, since the blade tip / reference portion measuring means 61 for measuring the distance L3 between the reference portion 7s of the tool post 7 serving as the tool support and the tip 18t of the tool 18 is provided, the tool is changed. Even if the mounting position of the tool 18 with respect to the tool rest 7 is changed, the distance L3 between the reference portion 7s of the tool rest 7 and the tool tip 18t can be recognized by actual measurement. Therefore, the position of the tool tip 18t can be managed with high accuracy, and the processing dimension accuracy can be improved.

  In this example, the measuring means 61 between the blade edge and the reference portion is an image pickup device 62 capable of simultaneously shooting the reference portion 7s and the tool tip 18t, and the reference portion 7s and the tool tip 18t simultaneously shot by the image pickup device 62. Image processing means 63 for processing an image including the image and calculating a distance L3 therebetween. As described above, since the reference portion 7s and the tool tip 18t are simultaneously photographed, the distance L3 between the reference portion 7s and the tool tip 18t can be calculated and accurately obtained by image processing. As a result, the distance L between the spindle axis O and the tool tip 18t can be obtained with high accuracy using the measured value of the distance L4 between the spindle axis O and the reference portion 7s of the tool post 7, and with high accuracy. Can be processed.

6 and 7 show another embodiment of the present invention. Except for the matters specifically described, the second embodiment is the same as the first embodiment described above with reference to FIGS. In this embodiment, the cutting edge / reference portion measuring means 61A includes two image pickup devices 62 ₁ and 62 ₂ for picking up the reference portion 7s and the tip 18t of the tool 18, respectively, and these two image pickup devices 62 _1. , 622, _two images G1 and G2 (FIG. 7) are respectively processed, and the reference portion 7s and the tool tip 18t with respect to the reference positions G1O and G2O such as the image origin in each of the images G1 and G2 are processed. Image processing means 63A for obtaining the coordinate positions G1Xs and G2Xt, the coordinate positions G1Xs and G2X of the reference portion 7s and the tool tip 18t obtained by the image processing means 63A, and the reference positions of the two images G1 and G2. The image processing result combining means 65 for calculating the distance L3 between the reference portion 7s and the tool tip 18t from the data of the actual distance LX between G1O and G2O. Become. Note that “actual” in the above “actual distance LX” means that it is not a distance on the image as described above.

The imaging devices 62 ₁ and 62 ₂ include a CCD camera or the like using a solid-state imaging device, and are attached to the side surface of the headstock 5 via the attachment member 64 so as to face forward in the Z-axis direction. Both 62 ₁ and 62 ₂ are arranged apart from each other by an assumed distance between the reference portion 7s and the tool tip 18t, and the field of view of the image can respectively pick up the reference portion 7s and the tool tip 18t. The field of view does not allow the entire tool 18 to enter. The imaging devices 62 ₁ and 62 ₂ may be installed at any position where the reference portion 7s and the tool tip 18t can be photographed, and may be installed on the bed 3 or the like.

The image processing result synthesis means 65 is provided in the control device 2, for example. In the image processing result synthesizing unit 65, the data of the actual distance LX between the reference positions G1O and G2O of the two images G1 and G2 is set in a storage unit (not shown). An appropriate test or simulation using a master tool (not shown) or the like may be obtained or corrected.
The distance L3 between the reference portion 7s and the tool tip 18t obtained by the image processing result combining means 65 is input to the calculation means 40 of the reference distance measuring means 29.

In the case of this configuration, since the two imaging devices 62 ₁ and 62 ₂ are used, the distance L3 between the reference portion 7s and the tool tip 18t is accurately measured even with the imaging devices 62 ₁ and 62 ₂ having a small number of pixels. it can. That is, as in the first embodiment, when the reference portion 7s and the tool tip 18t are simultaneously photographed, a wide range of imaging is performed. Therefore, in order to obtain the distance L3 with high accuracy, the imaging device 62 is used. It is necessary to increase the number of pixels, and the amount of processing data for image processing increases, which takes time. However, as described above, by separately capturing the reference portion 7s and the tool tip 18t with the _two image capturing devices 62 ₁ and 62 ₂ , the images G1 and G2 may be captured images in a narrow range. Even if the number of pixels ₁ and 62 ₂ is small, the distance L3 between the reference portion 7s and the tool tip 18t can be obtained with high accuracy. In addition, the amount of processing data for image processing is small, and measurement can be performed quickly. Therefore, highly accurate measurement can be performed quickly.

  FIG. 8 shows still another embodiment of the present invention. Except for the matters specifically described, the second embodiment is the same as the first embodiment described above with reference to FIGS. In this embodiment, the measuring means 61B between the cutting edge and the reference part moves the reference part 7s and the tip 18t of the tool 18 in the separating direction (X-axis direction) between the reference part 7s and the tool tip 18t, respectively. The image pickup device 62B for photographing the image, the image of the reference portion 7s and the image of the tool tip 18t (not shown) individually picked up are processed, respectively, and the reference portion 7s with respect to the reference position in each image is processed. And the image processing means 63B for obtaining the coordinate position of the tool tip 18t, the reference position 7s and the coordinate position of the tool tip 18t obtained by the image processing means 63B, and the movement distance data of the imaging device 62B. And an image processing result synthesis means 65B for calculating a distance L3 between the tool tip 18t.

  The imaging device 62B may be installed so as to be relatively movable in the separation direction (X-axis direction) between the reference portion 7s and the tool tip 18t. In this example, the imaging device 62B is attached to the side surface of the headstock 5 via the attachment member 64. It is attached in the forward direction in the Z-axis direction.

  The image processing result synthesis unit 65B is provided in the control device 2, for example. The data of the moving distance of the imaging device 62B used in the image processing result synthesis unit 65B is obtained by, for example, causing the spindle position measuring unit 20 to measure the position when the imaging device 62B images the reference portion 7s and the tool tip 18t, and the measurement result. The movement distance data is obtained from the above. In addition, the data of the moving distance of the imaging device 62B used in the image processing result synthesizing unit 65B is a fixed set value, and the position when the imaging device 62B images the reference portion 7s and the tool tip 18t is accurately controlled. You may do it.

  Also in this configuration, by separately imaging the reference portion 7s and the tool tip 18t, it is sufficient to capture a narrow range. Even if the number of pixels of the imaging device 62B is small, the reference portion 7s and the tool tip 18t can be accurately captured. The distance L3 can be obtained. In addition, the amount of processing data for image processing is small, and the calculation processing time can be shortened even if the capability of the image processing means 63B is low.

  FIG. 9 shows still another embodiment of the present invention. Except for the matters specifically described, the second embodiment is the same as the first embodiment described above with reference to FIGS. In this embodiment, the cutting edge / reference portion measuring means 61C includes one contact sensor 67 for detecting the position by contact, and the detected values of the positions of the reference portion 7s and the tool tip 18t measured by the contact sensor 67. The distance calculating means 68 for obtaining the distance L3 between the reference portion 7s and the tool tip 18t from the difference between the two.

  The contact sensor 67 uses a sensor that outputs an ON signal when a contact such as a touch probe comes into contact. The contact sensor 67 may be installed on an object that can move relative to the tool rest 7 in the X-axis direction. In this example, the contact sensor 67 is installed on the headstock 5 via a sensor entry / exit mechanism 69. The sensor entry / exit mechanism 69 is a swivel arm 70 installed on the headstock 5 so as to be rotatable up and down around a horizontal swivel axis Q along the separation direction (X-axis direction) between the reference portion 7s and the tool tip 18t. And an arm drive source 71 for rotating the swivel arm 70. The contact sensor 67 is installed at the tip of the turning arm 70. The arm drive source 7 may be an electric motor or a rotary actuator, and is a direct-acting fluid pressure cylinder for turning the turning arm 70 via a link (not shown). Also good. In this embodiment, the contact sensor 67 detects the reference portion 7s by contacting the back surface of the detected member 7S provided on the reference portion 7s of the tool post 7.

  The distance calculation means 68 includes the X-axis direction position of the headstock 5 which is the position in the X-axis direction of the contact sensor 67 when the contact sensor 67 detects the reference portion 7s, and the contact sensor 67 determines the tool tip 18t. The detected position of the headstock 5 in the X-axis direction is taken in from the X-axis direction position detecting means such as the spindle-side position measuring means 20 and the distance L3 between the reference portion 7s and the tool tip 18t is obtained.

  The distance calculation means 68 is provided in the control device 2, for example. The inter-reference distance measuring means 29 uses the distance L3 between the reference portion 7s and the tool tip 18t output from the distance calculating means 68 for calculation.

  In the case of this configuration, since the contact type sensor 67 is used, an operation time for measurement is required, but the blade tip / reference portion measuring means 61 </ b> C may have a simple configuration.

  In addition to the above embodiments, a laser scanning device (not shown) may be used instead of the imaging device as the cutting edge / reference portion measuring means. When using a laser scanning device, for example, as in the embodiment of FIG. 8, the laser scanning device is installed on the headstock 5 or another movable body (not shown) that is movable in the X-axis direction. The distance L3 between the reference portion 7s and the tool tip 18t is obtained from the data of the position of the laser scanning device when the laser scanning device detects the reference portion 7s and the tool tip 18t by the movement. In addition to this, the laser scanning device is optically scannable, and is installed in a fixed position on the bed 3 or the like, detects the reference portion 7s and the tool tip 18t by optical scanning, and determines the distance L3 between them. It is good also as what is measured.

  Next, specific examples of the spindle-side position measuring means 20 and the cutter-side position measuring means 30 will be described with reference to FIGS. This figure shows the details of the first embodiment described with reference to FIGS.

  The spindle-side position measuring means 20 is a means for measuring the position of the spindle axis O in the spindle radial direction (X-axis direction) with respect to the first reference position P1, and includes a scale 21 and a reading unit 22. The scale 21 is a rod-like member, and a base portion 21a is attached to a position in the vicinity of the axis O of the main shaft 6 in the main shaft radial direction in the feed base 4, and extends from the base portion 21a along the main shaft radial direction. The term “near the axial center” means that the axial center position is included. Compared to the case where the base 21a of the scale 21 is attached to the axial center position, the difference in measurement results caused by thermal displacement can be ignored. The distant range is called “near the axis”. The “near the axis” mentioned below has the same meaning as described above. In the illustrated example, the scale 21 is attached to the front surface of the feed base 4 via the space member 25, but may be attached to other locations, for example, near the front end of the upper surface or the lower surface of the feed base 4. A scale 23 is provided along a radial direction of the main axis in a predetermined range of the surface of the scale 21 facing the reading unit 22. The reading unit 22 reads the scale 23 of the scale 21, and is attached to the first reference position P <b> 1, which is a position on the bed 3, via the attachment member 24. For example, the reading unit 22 is an optical type, and reads the scale 23 by projecting detection light and receiving reflected light. Alternatively, the reading unit 22 may be a magnetic type.

  The range where the scale 23 is attached to the scale 21 is such that the headstock 5 is located at a position where the cutting edge of the tool 18 of the tool post 7 is in contact with the outer diameter of the workpiece W (FIG. 3) having the largest diameter that can be gripped and processed by the chuck 17a. A range from a position corresponding to the reading unit 22 to the origin position that is a position corresponding to the reading unit 22 when the axis O of the main shaft 6 is the same as the position of the tool 12 in the radial direction of the main shaft, or The length of the maximum heat displacement can be measured at one or more points within the range. When the headstock 5 is movable in the radial direction of the spindle as in this embodiment, if the scale 23 of the scale 22 is attached only to the indispensable minimum range as described above, the movement of the headstock 5 can be handled. And can perform the necessary position measurement. Cost can be reduced by minimizing the range of the scale 23. Further, the scale 23 is made fine for the range corresponding to the movement of the headstock 5 at the time of machining, and the scale 23 is set for the range where the headstock 5 moves only at the time of workpiece exchange, chuck exchange, etc. other than during machining. If it is roughened, the cost can be further reduced. The scale 23 may be provided over the entire length of the scale 22.

  The tool side position measuring means 30 is a means for detecting the position of the reference portion 7 s of the tool base 7 in the principal axis radial direction (X axis direction) with respect to the second reference position P 2, and includes a scale 31 and a reading unit 32. The scale 31 is a round bar-like member, and a base portion 31a is attached to the rotation center of the tool post 7 and extends through the hollow shaft 7c along the main shaft radial direction, that is, the rotation center T. The base 31a of the scale 31 is fixed to the tool post 7, but except for the base 31a, the base 31a is rotatable and advanceable / retractable with respect to the hollow shaft 7c. Scales 33 arranged in the radial direction of the main shaft are attached to the entire periphery of the end of the scale 31 protruding from the hollow shaft 7c so as to correspond to the reading unit 22. The reading unit 32 has an annular shape for reading the scale 33 of the scale 31, and is fixedly attached to the second reference position P <b> 2 that is a position on the bed 3 through an attachment member 34. The reading unit 32 may also be an optical type or a magnetic type.

  The reading unit 22 of the spindle-side position measuring unit 20 and the reading unit 32 of the blade-side position measuring unit 30 make the spindle radial position completely coincide with each other or due to the difference in the spindle radial position between the reading units 22 and 32. Align the thermal displacement in the radial direction of the spindle so that it can be ignored or estimated. That is, the main shaft radial direction positions of the first reference position P1 and the second reference position P2 are aligned.

Each reading value of the reading unit 22 of the spindle-side position measuring unit 20 and the reading unit 32 of the blade-side position measuring unit 30 is input to the calculation unit 40 of the control device 2. In this embodiment, the calculation means 40 is provided in the control device 2, but may be provided separately from the control device 2.
The calculating means 40 calculates the spindle axis O in the main spindle radial direction (X-axis direction) from the reading value of the reading section 22 of the main spindle side position measuring means 20 and the reading value of the reading section 32 of the blade side position measuring means 30. And the reference portion 7s of the tool support 7 calculated by the cutting edge / reference portion measuring means 61 (61A, 61B, 61C) and the tool. A means for calculating a relative distance L between the spindle axis and the cutting edge, which is a distance between the spindle axis O and the tip of the tool 18, from the distance L3 between the tips 18t.

  FIG. 11 shows the positions of the headstock 5 and the tool rest 7 at the normal temperature (solid line) and the positions of the head rest 5 and the tool rest 7 at the time of temperature rise (two-dot chain line). The relative distance L0 between the spindle center and the cutting edge at normal temperature (for example, 15 ° C.) is obtained from known dimensions of the machine tool and the tool 18. The calculation means 40 calculates the thermal displacement amount ΔL1 in the spindle radial direction of the spindle stock 5 due to the temperature rise from the reading values of the reading section 22 of the spindle position measurement means 20 and the reading section 32 of the tool position measurement means 30 and the tool rest 7. Is calculated, and the relative displacement L between the spindle center and the cutting edge during operation is obtained by adding the thermal displacement amounts ΔL1 and ΔL2 to the relative distance L0 between the spindle center and the cutting edge at room temperature. Is calculated.

This will be described in more detail.
The spindle-side position measuring means 20 reads the scale 23 of the scale 21 with the reading unit 22. Since the reading unit 22 is mounted on the bed 3 in a fixed position, the reading position of the reading unit 23 indicates the position in the radial direction of the main shaft of the feed base 4 to which the scale 21 is mounted. By adding the positional relationship between the feed base 4 and the spindle stock 5 to the position of the feed stock 4, the position of the spindle stock 5 in the radial direction of the spindle can be known. That is, the distance L1 between the first reference position P1 and the spindle axis O is known. The feed table 4 moves in the spindle radial direction during machining, but the movement amount is detected by another detection means (not shown), and the detected movement amount is added to always add the detected movement amount to the spindle radial direction. The position can be determined. From the position of the spindle base 5 in the radial direction of the spindle, the amount of thermal displacement ΔL1 in the radial direction of the spindle at the time of machining with respect to normal temperature is obtained.

  Further, the blade side position measuring means 30 reads the scale 33 of the scale 31 by the reading unit 32. Since the reading unit 32 is fixedly mounted on the bed 3, the reading of the reading unit 32 can be used to determine the radial position of the tool post 7 to which the scale 31 is attached. That is, the distance L2 between the second reference position P2 and the position of the tool tip 18t of the tool post 7 is known. From the radial direction position of the tool post 7 in the main shaft radial direction, a thermal displacement amount ΔL2 in the main shaft radial direction during machining with respect to normal temperature is obtained. Here, the amount of thermal displacement of the tool rest 7 is regarded as the amount of thermal displacement of the tool tip position of the tool 18 attached to the tool rest 7, but the amount of thermal displacement of the tool tip position is the heat of the tool rest 7. You may make it obtain | require by adding appropriate correction | amendment with respect to displacement amount.

  As described above, the calculation means 40 adds the calculated thermal displacement amounts ΔL1 and ΔL2 to the relative distance L0 between the spindle center and the blade edge at normal temperature, thereby increasing the temperature during operation or the like. The relative distance L between the spindle axis and the cutting edge is calculated. The relative distance L between the spindle axis and the cutting edge is obtained by adding a dimensional change due to thermal displacement to the relative distance L0 between the spindle axis and the cutting edge at normal temperature, and indicates the current accurate distance. The calculation result of the calculation means 40 is stored in the calculation means 40 or the thermal displacement correction means 43 (FIG. 1). Instead of obtaining the relative distance L between the spindle axis and the cutting edge, a change in the relative distance L between the spindle axis and the cutting edge may be obtained.

DESCRIPTION OF SYMBOLS 1 ... Machine tool main body 2 ... Control apparatus 3 ... Bed 5 ... Spindle head 6 ... Spindle (work support body)
7 (tool post) tool support 7s ... reference part 7S ... detected member 18 ... tool 18t ... tip 20 ... spindle side position measuring means 21 ... scale 22 ... reading part 29 ... inter-reference distance measuring means 30 ... tool post side Position measuring means 31 ... Scale 32 ... Reading section 40 ... Calculating means 61, 61A, 61B, 61C ... Measurement means 62, 62 ₁ , 62 ₂ , 62B between the cutting edge and reference part ... Imaging devices 63, 63A, 63B ... Image processing means 65 ... Image processing result synthesis means 67 ... Contact type sensors G, G1, G2 ... Image GP ... Origin G1O, G2O ... Reference position G1Xs, G2Xt ... Distance G1Xs, G2X ... Coordinate position L ... Relative distance L3 between spindle axis and cutting edge ... Distance (measurement target dimensions)
L4 ... Distance O ... Spindle axis (work support side reference position)
W ... Work

Claims (6)

A workpiece support that supports the workpiece; and a tool support that supports the tool by attaching the tool to a predetermined reference portion. The workpiece support and the tool support are moved relative to each other to bring the tip of the tool into contact with the workpiece. A machine tool for cutting a workpiece,
A machine tool comprising a cutting edge / reference portion measuring means for measuring a distance between the reference portion of the tool support and the tip of the tool along the relative movement direction.   The cutting edge / reference portion measuring means processes an image including the reference portion and the tip of the tool by simultaneously imaging the reference portion and the tip of the tool, and processing the image including the reference portion and the tip of the tool simultaneously photographed by the imaging device. 2. The machine tool according to claim 1, comprising image processing means for calculating a distance between the reference portion and the tip of the tool.   The measuring means between the cutting edge and the reference part respectively processes two images obtained by the two imaging devices that respectively photograph the reference part and the tip of the tool, and processes each of the images. Image processing means for obtaining the coordinate position of the reference portion and the tip of the tool with respect to the reference position at the reference position, the coordinate position of the reference portion and the tip of the tool obtained by the image processing means, and the two images of the two images The machine tool according to claim 1, comprising image processing result synthesis means for calculating a distance between the reference portion and the tip of the tool from data of an actual distance between the reference positions.   The measuring means between the cutting edge and the reference part moves the reference part and the tip of the tool in the separating direction of the reference part and the tool tip, and individually images the imaging part. An image processing means for processing the image of the reference portion and the image of the tip of the tool to obtain the coordinate position of the reference portion and the tip of the tool with respect to the reference position in each image, and the image processing means The image processing result synthesis means for calculating a distance between the reference portion and the tip of the tool from the coordinate position of the reference portion and the tip of the tool and the data of the moving distance of the imaging device. The machine tool described.   The measuring means between the cutting edge and the reference part is a contact type sensor that detects a position by contact, and a difference between detected values of the position of the reference part and the tip of the tool measured by the contact type sensor, the reference part The machine tool according to claim 1, further comprising: a distance calculating means for obtaining a distance between the tips of the tools.   The inter-reference distance measuring means for measuring a distance between a work support side reference position which is a reference position for supporting the work of the work support and the reference portion of the tool support is provided. The machine tool according to any one of 5.

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