JP2006051561A - Tool abnormality detection device in machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool abnormality detection device capable of detecting breakage of a tool including a multiple blade tool and winding of chips around a tool. <P>SOLUTION: One end of a weight sensor 17 to measure tool weight on a dividing base 13 of a tool magazine 8 and a tool pot 19 to hold the tool is mounted on the other end of the weight sensor 17. Weight of the tool T after processing which is installed on the tool pot 19 is measured for each of the tool pot 19 in accordance with tool changing movement between a main spindle 3a and the tool magazine 8. A measured value of the weight of only the tool T after processing which is found from the measured value and a standard weight value of the tool T previously measured are compared with each other. A tool state is discriminated from the compared result. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tool abnormality detection device that detects breakage, chipping, and chip winding of a machining tool in a machine tool.

  Conventionally, as described in Patent Document 1, the tool length is checked by a touch sensor on the tool passage path for tool change operation to detect the presence or absence of tool breakage, as described in Patent Document 2, A photoelectric sensor with a light-emitting element and a light-receiving element facing each other is provided in the middle of the tool movement trajectory by the tool change arm that exchanges the tool with the spindle, and the tool tip breaks between the photoelectric sensors. Various types of blade breakage detection devices are known, such as a device for detecting tool breakage, and a device for detecting tool breakage when a detector contacts a tool tip when a tool mounted on a spindle is returned to a tool magazine.

  As in Patent Document 4, a weight sensor is provided on a moving table of a tool setup unit for setting up a loading / unloading of a tool magazine rack for a newly used tool or an unnecessary tool, and the tool is loaded prior to loading the tool into the rack. It is also known that the weight of the tool is measured and stored in advance, and the rotational speed of the tool changing arm is optimized or the tool conveying speed is optimized based on the weight.

  In Patent Document 5, a workpiece is machined with a tool such as a drill, the workpiece weight after machining is measured with a weight detector, and if the measured value is heavier than the reference workpiece weight after machining, the cutting tool breaks. Has disclosed a machining abnormality detection device for detecting, for example, uncut portions. Patent Document 6 discloses a device that detects a chip defect by imaging a multi-blade tool with a camera and analyzing it from image data.

JP-A-11-90786 JP 2000-176776 A Utility Model Registration No. 2603656 JP 2001-105266 A JP 58-56753 A JP-A-10-96616

The ones in Patent Documents 1 to 3 are suitable for detecting the tip breakage of a cutting tool mainly shaped like a drill, but are applicable to multi-blade tools having a plurality of tips at the tip, such as a milling cutter. There is a difficult problem. In addition, even in the case of a cutting tool such as a drill, the abnormalities such as chips wound around the cutting tool cannot be handled by the ones in Patent Documents 1 to 3.
In the technique of Patent Document 4, the tool weight is measured, but the detected value of the tool weight is not used for determining the tool state. Patent document 5 is intended to determine the tool state indirectly by measuring the workpiece weight after machining, and does not discriminate the tool state from the tool weight.
With the technique of Patent Document 6, chip defects of a multi-blade tool can be detected, but this is an extremely expensive facility that involves image analysis, and there is an aspect that is difficult to adopt from the viewpoint of cost.
This invention provides the tool abnormality detection apparatus which can detect the tool breakage including a multiblade tool, and the winding of the chip | tip with respect to a tool.

  A tool abnormality detection device for a machine tool according to the present invention is a weight sensor for measuring a tool weight after processing in a machine tool in which a tool is exchanged between a spindle and a tool magazine, and a measurement value by the weight sensor. And a reference weight value of the tool measured in advance, and a discriminating means for discriminating the tool state based on the comparison result.

  A tool pot that holds the tool at the time of tool change is attached to the reference side member via the weight sensor, and when the tool is attached to the tool pot during the tool change operation, the tool weight is measured together with the tool pot. .

  The reference side member is used as an index base of the tool magazine, and a plurality of tool pots provided on the index base are respectively attached to the index base via weight sensors, and the tool after machining from the spindle to each tool pot is loaded. When returned, the weight sensor measures the tool weight together with the tool pot.

  The tool abnormality detection device in the machine tool of the present application may be configured such that the tool transfer is performed between the spindle and the tool transfer device, and the tool transfer is performed between the tool transfer device and the tool magazine. A weight sensor is provided on the transfer base of the apparatus, and a determination means for comparing the measured value by the weight sensor with the reference weight value of the tool measured in advance and determining the tool state based on the comparison result is provided. It is characterized by.

  The discriminating means includes a first discriminating means for judging that the tool is broken when a weight value smaller than the reference weight value is detected by the weight sensor, and a chip winding abnormality when the weight value larger than the reference weight is detected by the weight sensor. 2nd discriminating means for judging.

In the device of the present application, when the tool weight is lightened due to breakage of the tool or when the tool weight is increased due to wrapping of chips, it can be detected by comparison with a reference weight where such a situation does not occur. Further, even in a multi-blade tool such as a milling cutter, the tool weight changes due to chipping or the like, and thus tool abnormality of such a multi-blade tool can be detected.
In addition, the tool pot that holds the tool when changing the tool is attached to the reference side member via the weight sensor, and the tool weight is detected when the tool is mounted on the tool pot after processing. Without providing a special detection step, the weight can be measured in the tool change operation, and the tool change operation does not become long.

  As shown in FIGS. 1 and 2, on the base 2 of the machine tool 1, a main shaft 3 a that can be moved up and down is provided on the front surface, a movable column 3 that can be moved back and forth and left and right, and a work base 4 on which a work W is placed. And are installed. At the rear of the base 2, a pair of left and right columns 5, 6 are provided outside the left and right movement range of the movable column 3, and the support base 7 is fixed to the upper end of the columns 5, 6 in a cantilever state. And located above the moving column 3. A tool magazine 8 holding a plurality of tools T is provided on the upper side of the support base 7, and the tool T is placed on the lower surface of the support base 7 between the tool magazine 8 and the main shaft 3 a of the moving column 3. A tool changer 9 having an exchange arm 9a to be exchanged is attached. In normal machining, the machine tool 1 is mounted with a tool T on the main shaft 3a of the moving column 3 from the tool magazine 8 by the tool changer 9, and the jig 3 is moved by moving the moving column 3 back and forth, right and left and up and down the main shaft 3a. The workpiece W held on the base 4 is processed. Reference numerals 10 and 11 are side covers installed on the base 2 of the machine tool 1. Further, a control means 12 is provided in the rear portion of the machine tool 1, and executes machine operation control according to a normal machining program and tool state detection by a tool abnormality detection program described later.

  The index base 13 of the tool magazine 8 is a reference side member. As shown in FIG. 4, the index base support member 14 provided on the support base 7 can be pivotally indexed by the pivot shaft 13 a of the index base 13. It is supported by. The turning shaft 13 a is connected to the indexing motor 16 through the gear device 15. A plurality of weight sensors 17 are provided on the front surface 13b of the index base 13 at equal intervals in the circumferential direction. The weight sensor 17 is a well-known load cell. Briefly described, a strain gauge (not shown) is attached to the upper and lower surfaces of the strain body 18, and the strain gauge is electrically bridge-connected to form the strain body. The strain-generating body 18 is deflected when a load is applied to the free end at the other end, and the strain gauge attached to the strain-generating body 18 is distorted. The output electrical signal (resistance) Value) changes, and the output electric signal is converted into weight and the weight is measured. One end of the strain generating body 18 is fixed to the front surface 13b of the index base 13, and a tool pot 19 for holding the tool T is fixed to the other end which is a free end. The output electric signal from the weight sensor 17 is input to the control means 12, and the control means 12 measures the total weight of the tool pot 19 and the tool T. The weight sensor 17 and a discrimination means described later constitute a tool abnormality detection device.

  A fixed shaft 20 fixed to the support base 7 passes through the center of the index base 13 (FIG. 4), and a pot presser 22 of a pot presser device 21 is provided at the front end portion of the fixed shaft 20. The support base 7 is also provided with a pot presser 23. The pot pressers 22 and 23 are arranged so as to be opposed to each other in the vertical direction with the tool pot 19 indexed at the indexing position P1 shown in FIGS. 3 and 4, and the outer peripheral surface of the tool pot 19 is viewed from above and below. It can be pinched. These pot pressers 22 and 23 may have an appropriate configuration. For example, a holding member 26 is provided at the tip of the rod 25 of the cylinder 24, and the tool pot 19 is held by the protrusion and withdrawal of the rod 25. The pot presser 21 is controlled by the control means 12. In response to a command from the control device 12, the pot presser device 21 starts turning from the standby position shown in FIG. 5 in the timing chart of the replacement arm 9a shown in FIG. The tool pot 19 is clamped until 9a moves backward and both the tool pot 19 and the tools T and T of the spindle 3a are replaced and mounted. By holding the tool pot 19 of the pot presser device 21, the impact at the time of tool change is not transmitted directly to the weight sensor 17.

  The exchange arm 9a of the tool changer 9 is connected to a drive motor 29 via a turning mechanism 27 and an advance / retreat mechanism 28 as shown in FIG. When the drive motor 29 is driven, the exchange arm 9a turns 90 degrees in the forward direction (right rotation in FIG. 5) and 90 degrees in the opposite direction (left rotation in FIG. 5) by the turning mechanism 27, The advancing / retreating mechanism 28 advances and retracts in the axial direction. According to the timing chart shown in FIG. 6, the exchange arm 9a holds the tool T held in the tool pot 19 indexed from the horizontal standby position to the indexing position P1 of the tool magazine 8 and the tool T at the tip of the spindle 3a. The tool T at the indexing position P1 and the tool T at the tip of the main shaft 3a are gripped by turning 90 degrees in the forward direction to the gripping position to be moved, and then moved forward in the main shaft axis direction so that both the tools T and T are indexed. The tool pot 19 of P1 is extracted from the tip of the spindle 3a, rotated 180 degrees in the forward direction, the positions of both tools T and T are changed, and then moved back in the axis direction of the spindle to place the tools T and T at the index position P1. The pot 19 and the spindle 3a are respectively attached to the tips of the main shaft 3a, turned 90 degrees in the reverse direction to release the tool T from the gripping position, and returned to the standby position. The drive motor 29 includes an encoder 30 that detects the rotation of the drive motor 29, and the encoder 30 is connected to the control device 12. The rotation of the drive motor 29 of the tool changer 9 is controlled based on a command from the controller 12, and an input pulse for detecting the amount of rotation of the drive motor 12 is input from the encoder 30 to the controller 12. Each step of the tool holder replacement operation is detected based on this input pulse.

  The control device 12 performs a tool abnormality detection process according to the tool abnormality detection program shown in the flowchart of FIG. First, when the tool change is started, the tool abnormality detection program holds the tool pot 19 pivoted to the indexing position P1 shown in FIGS. 3 to 5 in the tool magazine 8 by the pot presser 21 in step S1. Then, it is determined based on the input pulse from the encoder 30 whether the 270 degree turn in the forward direction of the exchange arm 9a and the reverse completion timing have come. When the 270-degree turning and reverse completion timing of the exchange arm 9a is detected, the tool pot 19 is released from the pot presser device 21 in step S2, the total weight of the tool T and the tool pot 19 is applied to the weight sensor 17, and the index position P1. The output electric signal from the weight sensor 17 is read into the control device 12 and the total weight of the tool T and the tool pot 19 is measured.

  Next, in step S3, a measured value of the tool weight of only the tool T is calculated from the measured value of the total weight of the tool T held in the tool pot 19 measured in step S2, and the measured value of the tool weight of the tool T and its value are calculated. A reference weight value corresponding to the measured tool number of the tool T is compared, and the tool state is determined based on the comparison result. Here, the reference weight value of each tool T is registered in advance in the control device 12 for each tool number which is a number for identifying each tool T. Of course, the total weight of the tool T and the tool pot 19 may be registered in advance as a reference weight value and compared with the measured value of the total weight of the tool T and the tool pot 19 measured by the weight sensor 17. When the measured value of the tool weight measured in step S3 is smaller than the reference weight value, the process proceeds to step S4. At this time, since the measured weight of the tool T is reduced due to breakage or chipping, it is determined that the tool is broken in step S4, and a tool abnormality is notified by a notification means (for example, an alarm) in step S5. If the measured value of the tool weight measured in step S3 is larger than the reference weight value, the process proceeds to step S6. At this time, since the measured weight of the tool T is increased due to the winding of the chip, it is determined in step S6 that the chip winding is abnormal, and in step S7, the tool abnormality is notified by the notification unit. Further, if the weight of the tool T measured in step S3 is a reference weight value, it is determined normal in step S8.

  When the tool abnormality is notified by the notification means in steps S5 and S7, thereafter, an appropriate measure is taken such that an operator takes out the tool T stored in the tool magazine 8 and replaces the tool T. In step S3, a tool weight measurement value is calculated from an electrical signal output from the weight sensor 17 indicating the measurement value of the total weight of the tool pot 19 and the tool T, and the tool weight is compared with the reference weight value of the corresponding tool T. It is a value calculation comparing means, based on the comparison result of step S3, step S4 is a first determining means for determining tool breakage, step S6 is a second determining means for determining chip winding abnormality, S8 is a third discriminating means for judging that it is normal. Steps S3, S4, S5 and S8 constitute the discriminating means. In step S3, the determination is made using the reference weight value of each tool T registered in advance in the control device 12. However, the tool weight is measured with the tool weight measured at the end of the previous machining as the reference weight value and corresponds to the tool number. Then, it can be stored in the control device 12 and used for comparison of the tool weight.

  Next, a second embodiment will be described. This is because a tool transfer device 31 is arranged between the tool magazine 8 and the tool changer 9, the tool T is exchanged between the spindle 3 a and the tool transfer device 31, and between the tool transfer device 31 and the tool magazine 8. The weight sensor 17 is provided in the transfer base 32 for transferring the tool T of the tool transfer device 31, and the tool state of the machined tool T after processing is substantially the same as in the first embodiment. It discriminate | determines from the measured value of the tool weight measured by this. As an example, a machine tool 1 shown in FIGS. 8 and 9 will be described. A tool transfer device 31 is provided between the tool magazine 8 and the spindle 3a, and the tool pot 19 holding the tool T is detachably grasped by a pair of grippers (clamping members) 33 of the indexing base 13, and the first The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

  A plurality of grippers 33 are provided radially on the indexing base 13 with respect to the turning center. The tool magazine 8 is provided with a guide rail 34 on the outer peripheral side of the clamped tool pot 19. The guide rail 34 has an arc shape as shown in FIG. 8 and prevents the tool pot 19 from escaping outward in the radial direction of the index base 8, and the notch 35 is formed at the index position P1. Is formed. Further, a side guide 36 is provided on the base 37 on the support base 7 along the tool conveyance direction from the index position P1 to the tool change position P2 directly below, and the tool pot 19 is a transfer body 42 of the tool moving device 31. When the tool pot 19 is transferred from the index position P1 to the tool change position P2, the tool pot 19 is in sliding contact with the outer peripheral surface, and the tool pot 19 is prevented from being pulled out from the transfer body 42 in the left-right direction in FIG. A pot retainer 38 is provided at a portion of the base 37 corresponding to the tool change position P2 shown in FIGS. 8 and 9, and the tool pot 19 is held by a holding member 39 and a holding member 41 at the tip of the rod of the cylinder 40. Clamp it from the side. The tool transfer device 31 transfers the tool T at the index position P1 of the tool magazine 8 together with the tool pot 19 to the tool change position P2 that delivers to the tool change arm 9a. The transfer body 42 provided in the tool transfer device 31 holds the tool pot 19 swiveled and indexed at the index position P1, and is shown in FIG. 9 so that the tool pot 19 can pass at the index position P1. In this way, the tool magazine 8 is formed in a U-shaped cross section in which the turning index direction is opened. The transfer body 42 is attached to the other end of the strain body 18 of the weight sensor 17, and one end of the strain body 18 is fixed to the moving base 32 at the tip of the rod 44 of the transfer cylinder 43. The tool pot 19 is linearly transferred along the side guide 36 between the index position P1 and the tool change position P2. 45 is a guide rail for guiding the moving base 32.

  The tool abnormality detection is substantially the same as in the first embodiment. First, after the tool pot 19 indexed to the indexing position P1 is transferred to the tool changing position P2, the tool pot 19 is clamped by the pot presser 38. The tool T is exchanged between the tool T at the tool change position P2 and the tool T after machining the spindle 3a, and the tool pot 19 is released from the pot press device 38 in steps S1 and S2 according to the steps of the flowchart of FIG. A measured value of the total weight of the tool T, the tool pot 19 and the transfer body 42 after processing is measured by the control means 12 from the output electric signal from the weight sensor 17. At this time, the side guide 36 only comes into contact with the outer peripheral surface of the tool pot 19 from the side, so that the weight measurement is not affected. Next, in step S3, the measured value of the tool weight of only the tool T after machining is calculated from the measured value of the total weight, the measured value of the tool weight is compared with the reference weight value corresponding to the tool T, and the tool weight is compared. If the measured value is smaller than the reference weight value, steps S4 and S5 are executed and it is determined that the tool is broken. If the measured value of the tool weight is larger than the reference weight value, steps S6 and S7 are executed and the chips are cut. If it is determined that the winding is abnormal and the measured value of the tool weight is the reference weight value, it is determined that the tool is normal in step S8. Of course, the total weight of the tool T, the tool pot 19 and the transfer body 42 may be used as the reference weight value.

  In the first and second embodiments, the total weight of the tool pot 19 to which the tool T is mounted or the total weight of the tool T, the tool pot 19 and the transfer body 42 is measured, but only the tool weight of the tool T is measured. May be measured. Moreover, although the load cell was used as a weight sensor, it is not limited to this.

It is a front view of the machine tool provided with the tool abnormality detection device of the present invention. It is a side view of a machine tool. It is the front view which expanded the principal part. It is a side view which shows the outline | summary of a weight sensor and a pot presser. It is a figure which shows the outline | summary of a tool change apparatus. It is a timing chart of tool exchange. It is a flowchart which shows a tool abnormality detection program. It is a principal part front view of 2nd Example. It is a principal part side view of 2nd Example.

Explanation of symbols

1 Machine Tool 3a Spindle 8 Tool Magazine 13 Reference Side Member (Indexing Base)
17 Weight sensor 19 Tool pot 31 Tool transfer device 32 Moving base T Tool

Claims (5)

In a machine tool in which the tool is exchanged between the spindle and the tool magazine, a weight sensor that measures the weight of the tool after machining, a value measured by the weight sensor, and a reference weight value of the tool that has been measured in advance And a discriminating means for discriminating a tool state based on the comparison result, and a tool abnormality detecting device for a machine tool. A tool pot that holds the tool at the time of tool change is attached to the reference side member via the weight sensor, and when the tool is attached to the tool pot during the tool change operation, the tool weight is measured together with the tool pot. The tool abnormality detecting device for a machine tool according to claim 1. The reference side member is used as an index base of the tool magazine, and a plurality of tool pots provided on the index base are respectively attached to the index base via weight sensors, and the tool after machining from the spindle to each tool pot is loaded. The tool abnormality detection device for a machine tool according to claim 2, wherein when the tool is returned, the weight sensor measures the tool weight together with the tool pot. In a machine tool in which a tool is exchanged between the spindle and the tool transfer device and a tool is exchanged between the tool transfer device and the tool magazine, a weight sensor is provided on the transfer base of the tool transfer device, A tool abnormality detection device for a machine tool, comprising a determination means for comparing a measured value by a weight sensor with a reference weight value of the tool measured in advance and determining a tool state based on the comparison result. . The discriminating means includes a first discriminating means for judging that the tool is broken when a weight value smaller than the reference weight value is detected by the weight sensor, and a chip winding abnormality when the weight value larger than the reference weight is detected by the weight sensor. The tool abnormality detection device for a machine tool according to any one of claims 1 to 4, further comprising second determination means for determining.

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