JPH02176540A - Detecting device for wear of tool - Google Patents

Abstract

PURPOSE:To detect the abrasion of a grinding wheel in an early stage and to prevent in advance the working executed by a defective tool by detecting hydraulic pressure of a static pressure guide part for moving relatively a tool and a work, and deciding the wear amt. of the tool, based thereon. CONSTITUTION:When a grinding wheel 8 is worn out and becomes blunt, as a working resistance increases and decreases, hydraulic pressure of pockets 13 - 17 being static pressure guide parts to which this resistance is applied is also varied. Also, a deciding means decides the wear amt. of the wheel 8, based on the hydraulic pressure of the pockets 13 - 17 detected by pressure sensors 22, 24 and 25 being pressure detecting means. That is, when the wheel 8 is worn out and becomes blunt, main component force of the working resistance decreases and back component force increases. Also, as the main component force decreases, hydraulic pressure of the pocket 13 to which this force is applied decreases or increases, and as the back component force increases, hydraulic pressure of the pockets 14 - 17 to which this force is applied increases or decreases. Moreover, the deciding means decides the wear amt. of the wheel 8, based on the hydraulic pressure of the pocket 13 detected by the sensor 22, and the hydraulic pressure of the pockets 14 - 17 detected by the sensors 24, 25.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a tool wear detection device. [Prior Art] In general, tool abnormalities in processing machines, such as abrasion and chipping in cutting tools such as milling cutters, and wear, clogging, and spillage in grinding tools such as grindstones, are common.
When wear (hereinafter collectively referred to as wear) occurs, it has an adverse effect on the machined surface of the workpiece. Traditionally, operators judge tool wear based on the workpiece after machining. For example, in the case of a grinding wheel, when the workpiece surface becomes rough, grinding burns, etc. occur, or when the amount of cut during grinding occurs. However, when there is little change in the dimensions of the actual workpiece, it is determined that the grindstone is worn out, and the grindstone is dressed or replaced. [The invention tries to solve 1! ! However, as mentioned above, not only does it require considerable skill to judge the amount of wear on the grindstone, but wear cannot be determined unless the wear on the grindstone progresses to the extent that it adversely affects the machined surface of the workpiece. . Therefore, by the time the worker grasps the situation and takes action, the problem is that they have already done a considerable amount of grinding with a grinding wheel that is already worn out, and this applies not only to grinding wheels but to all machining tools. . The above-mentioned problems occur particularly in the case of unmanned automatic machining, and even though the machining process is automated, the current situation is that tool wear cannot be automatically managed. Therefore, there is a demand for the development of in-process measurement to achieve complete automation and unmanned operation. The purpose of the present invention is to be able to detect tool wear early without requiring the user to be skilled, to prevent machining with defective tools, and to support in-process measurement for unmanned automatic machining. An object of the present invention is to provide a tool wear detection device that can detect tool wear. [Means for Solving the Problems] A first invention includes a pressure detection means connected to a static pressure guide for relatively moving a tool and a workpiece in a processing machine, and detecting oil pressure at the same location; The gist of the present invention is a tool wear detection device comprising a determination means for determining the amount of wear of the tool based on the hydraulic pressure of the static pressure guide indicated by the pressure detection means. The second invention is connected to the first static pressure guide part to which the main force of the grinding resistance is applied during machining, among the static pressure guide parts for relatively moving the tool and the workpiece in the processing machine, and the same A first pressure detection means for detecting the hydraulic pressure at a location is connected to a second static pressure guide section of the static pressure guide section of the processing machine to which the force of the grinding resistance is applied during machining, and the hydraulic pressure at the same location is a second pressure detection means for detecting the pressure, a hydraulic pressure of the first static pressure guide section indicated by the first pressure detection means, and a hydraulic pressure of the second static pressure guide section indicated by the second pressure detection means. Based on the above, the gist of the present invention is to provide a tool wear detection device comprising a determination means for determining the amount of wear on the tool. [Function] When the tool wears and becomes dull, the hydraulic pressure of the static pressure guide to which this resistance is applied changes as the machining resistance increases or decreases. The determination means determines the amount of wear on the tool based on the hydraulic pressure of the static pressure guide detected by the pressure detection means. When the tool wears and becomes dull, the principal force of machining resistance decreases and the thrust force increases. As the principal force decreases, the oil pressure in the first static pressure guide to which this force is applied decreases or increases, and as the back force increases, the oil pressure in the second static pressure guide to which this force is applied increases or decreases. do. The determination means detects the tool based on the oil pressure of the first static pressure guide detected by the first pressure detection means and the oil pressure of the second static pressure guide detected by the second pressure detection means. Determine the amount of wear. [Example] Hereinafter, an example in which the present invention is embodied in a wear display device for a grinding wheel of a grinding machine will be described with reference to the drawings. As shown in FIG. 1, a spindle 2 that can move up and down within a column 1 of a grinding machine is provided with a main spindle head 3 so as to protrude forward, and a bearing sleeve 4 is fitted into the main spindle head 3. There is. A holding hole 4 provided through the bearing sleeve 4
The large diameter portion 5a of the main shaft 5 is rotatably inserted into the sleeve 4, and front and rear covers 6.7 are attached to the front and rear of the sleeve 4.
are opposed to step portions 5b formed on both sides of the large diameter portion 5a, and prevent movement of the main shaft 5 in the axial direction with respect to the bearing sleeve 4. A grindstone 8 as a tool is attached to the front end of the main shaft 5, and the rear end is connected via a coupling 10 to a motor 9 for driving the grindstone provided on the spindle 2. As shown in FIGS. 1 and 2, the outer periphery of the main shaft 5 and the holding hole 4
There is a fine gap 11 between the inner circumferential wall of a for static pressure guidance.
This gap 11 is also formed between the stepped portion 5b of the main shaft 5 and the front cover 6 and rear cover 7, respectively. In addition, right and left pockets 12 and 13 and upper and lower pockets 14 and 15 for static pressure guidance are provided at four equally divided locations on the inner circumferential wall of the holding hole 4a at the front and rear parts thereof, respectively. Front and rear cover 6゜7
Also provided are annular front and rear pockets 16, 17, respectively. An oil supply path and an oil recovery path (not shown) are connected to each of the pockets 12 to 17, and the hydraulic oil in the oil tank is supplied to each pocket 12 to 17 via the oil supply path by an oil pump.
After being pumped into the oil tank 17, the oil is collected into an oil tank via an oil recovery path. The right and left pockets 12.13 are used as first static pressure guide parts, and the upper and lower pockets 14.15 and the front and rear pockets 16.17 are respectively used as second static pressure guide parts. The hydraulic oil supplied into each of the pockets 12 to 17 fills the pockets 12 to 17 and forms an oil film in each gap 11. Therefore, the main shaft 5 is connected to the bearing sleeve 4.
is held in the holding hole 4a via an oil film, and
The grindstone is rotated clockwise by a motor 9 for driving the grindstone. The right, left, upper, and lower pockets 12 to 15 on the front side of the holding hole 4a open to the outer periphery of the flange of the bearing sleeve 4 via a hydraulic pressure detection path 18, and a coupler 19 is installed in each opening. It is screwed in. Right and left pressure sensors 20.21 as first pressure detection means are removably connected to the cover 19 communicating with the right and left pockets 12.13, respectively.
Coupler 19 communicating with upper and lower pockets 14°15
Upper and lower pressure sensors 22 and 23 as second pressure detection means are respectively detachably connected to the pockets 12 to 15 to detect the oil pressure in the respective pockets 12 to 15. The front pocket 16 opens on the outer periphery of the front cover 6 via an oil pressure detection path 18, and the rear pocket 17 opens on the outer periphery of the flange of the bearing sleeve 4 via an oil pressure detection path 18. Front side and invasion side pressure sensors 24.25 as second pressure detection sensors are removably connected to the screwed cover 19 to detect the oil pressure in the respective pockets 16.17. As shown in FIG. 1.2, each of the pressure sensors 20 to 25
is connected to a display panel 26, and on the front side of the display panel 26 is provided a display section 26a composed of an LED for displaying the wear state of the grindstone, and below the display section 26a is a display section 26a for measuring the wear amount of the grindstone. A grindstone designation dial 27 and a power switch 28 are provided for designating eight types. As shown in FIG. 3, a central processing unit (hereinafter referred to as CPU) 29 installed in the display panel 26 is connected to each of the sensors 20 to 25 and a grindstone designation dial 27, and a display section 26a is connected to the central processing unit (hereinafter referred to as CPU) 29. They are connected via a display drive circuit 32. Further, a random access memory (hereinafter referred to as RAM) 30 and a read only memory (hereinafter referred to as ROM) 31 are connected to the CPU 29, and RO
The M31 stores a program for determining whether the grindstone 8 is grinding the workpiece W and a program for determining the amount of wear on the grindstone 8, and the CPU 29 operates to display the amount of wear according to these programs. It is now possible to do this. Note that the RAM 30 is designed to temporarily store data for processing performed by the CPtJ 29. Next, we will describe the operation of the wear display device configured as described above, but before that, we will explain how the grinding resistance generated during grinding affects the oil pressure in each of the pockets 12 to 17. do. Needless to say, no grinding resistance is generated during idle running when the grindstone 8 separates from the workpiece W as the workpiece W reciprocates in the left-right direction. For this reason, the grindstone 8 and the main shaft 5 that supports it
Since no grinding resistance is applied to the gaps 11, all of the gaps 11 are uniform, and the resistance when the hydraulic oil flows from inside each pocket 12 to 17 to the oil recovery path through the gap 11 is equal. The pressure inside 17 is also all equal. As shown in FIG.
@When grinding, the thrust force F2 of the grinding resistance is applied to the grinding wheel 8.
This thrust force F2 also extends to the main shaft 5 supporting the grindstone 8. As a result, the gap 11 near the upper pocket 14 becomes narrower, making it difficult for the hydraulic oil that has flowed into the upper pocket 14 to be discharged to the oil recovery path, thereby increasing the oil pressure within the pocket 14. Also,
On the contrary, the gap 11 near the lower pocket 15 becomes wider, so that the hydraulic oil that has flowed into the lower pocket 15 is easily discharged to the oil recovery path, and the oil pressure in the pocket 15 decreases. Therefore, a pressure difference is generated between both pockets 14 and 15, and this pressure difference increases or decreases in accordance with the magnitude of the thrust force F2 applied to the grindstone 8. Furthermore, when the grindstone 8 is grinding the work W on its side surface, the thrust force F2 of the grinding resistance acts to move the grindstone 8 to the side opposite to the cutting direction (backward in FIG. 5). Similarly to the case described above, the oil pressure in either the front pocket 16 or the rear pocket 16 or 17 increases, and the oil pressure in the used pocket decreases. For this reason, both pockets 16.17
A pressure difference is generated between the two, and the pressure difference in this case also increases or decreases in accordance with the magnitude of the thrust force F2 applied to the grindstone 8. On the other hand, as shown in FIG. 4, since the grindstone 8 rotates clockwise during any of the grinding operations described above, the main force F1 of the grinding resistance acts to move the grindstone 8 to the right. Therefore, during grinding, the oil pressure in the right pocket 12 always increases while the oil pressure in the left pocket 13 decreases, and both pockets 12
．． A pressure difference occurs at 13. The pressure difference in this case increases or decreases in accordance with the magnitude of the principal force F1 applied to the grindstone 8. Generally, the ratio between the principal force F1 of the grinding resistance and the back force (=2) takes a value of about 1:1.5 to 1:2.5, and this value changes as the grinding wheel 8 wears. In other words, when a back force is generated by grinding a certain depth of cut, a principal force corresponding to the wear m of the grindstone 8 at this point is generated.For example, as shown by the broken line in FIG. In the case of an unused grindstone 8, the sharpness is good, so the ratio of the principal force F1 to the back force F2 is large.When the sharpness deteriorates due to wear, the principal force F1 decreases and the back force F2 increases. increases, reaching the wear limit shown by hatching in Fig. 7. In this way, when the grindstone 8 wears, the principal force F1 and the thrust force F
2 increases or decreases, and the oil pressure in each of the pockets 12 to 17 changes. Therefore, wear of the grindstone 8 can be determined based on the oil pressure in each of the pockets 12 to 17. Therefore, in anticipation of the occurrence of the above phenomenon,
A case in which the wear of the grindstone 8 is measured using this wear display device will be described in detail. First, the type of grindstone 8 whose wear amount is to be measured is indicated on the display 51.
826 with the whetstone designation dial 27, and this whetstone 8
Grinding is started on a workpiece W of a predetermined material using a predetermined cutting depth, workpiece feed rate, and grindstone rotation speed, and the power switch 28 on the display panel 26 is activated. Then, as shown in FIG.
The detected value of is synchronized with the reciprocating movement of the workpiece W, and alternately repeats a certain pressure value and a pressure value higher by a predetermined amount than that value, and the detected value of the left pressure sensor 21 is the same pressure value as the right pressure sensor 20. A pressure value lower than that by a predetermined amount is alternately repeated. The CPU 29 inputting this detection signal determines that when there is a pressure difference, it is during grinding, and when there is no pressure difference, it determines that the grindstone 8 is running idle when it is separated from the workpiece W. As mentioned above, during grinding, a pressure difference always occurs between the right and left pockets 12, 13, and when running idle, both pockets 12.
．． Since no pressure difference occurs between the right and left pressure sensors 20 and 21, the time when the pressure difference is detected by the right and left pressure sensors 20 and 21 can be regarded as the time of grinding, and the time when no pressure difference is detected can be considered as the time of idle running. . Next, CPtJ29 calculates the pressure difference indicated by the upper and lower pressure sensors 22 and 23 during grinding, and the front and rear pressure sensors 24. , 25 is larger. As mentioned above, the upper and lower pressure sensors 22
．． 23 shows a large pressure difference, and when the front and rear pressure sensors 24 and 25 show almost no pressure difference, the grinding wheel 8
On the contrary, the upper and lower pressure sensors 22 and 23 show almost no pressure difference, and the front and rear pressure hinges 24 and 25 show a large pressure difference. When shown, it can be assumed that grinding is being performed with the side surface of the grindstone 8. For example, when the upper and lower pressure sensors 22 and 23 indicate a large pressure difference, the CPU 29 determines that grinding is being performed by the outer peripheral surface of the grinding wheel 8, and the upper and lower pressure sensors 22 and 23 indicate that the The ratio between the pressure difference and the pressure difference indicated by the right and left pressure sensors 20, 21 during grinding is determined. As described above, as the grinding wheel 8 wears, the pressure difference indicated by the upper and lower pressure sensors 22.23 increases, and the pressure difference indicated by the right and left pressure sensors 20.23 increases.
Since the pressure difference indicated by 21 becomes smaller, it can be assumed that the ratio of the meat pressure difference also changes as the grindstone 8 wears. The ROM 31 stores the value of this ratio when not in use and at the wear limit for each grindstone 8 selected with the grindstone designation dial 27, and the CPU 29 stores the calculated ratio. Determine where it is between the ratio when not in use and the ratio at the wear limit stored in the ROM31, based on the ratio where the ratio at the time of unspecified condition is 100% and the ratio at the limit of use is 0%. and is displayed on the display section 26a of the display board 26. For example, if the grindstone 8 is close to the wear limit, a value close to 0% will be displayed, and the user will need to replace the grindstone 8 or perform a predetermined dressing operation. On the other hand, if the front and rear pressure sensors 24.25 indicate a large pressure difference, the CPU 29 determines that grinding is being performed by the side surface of the grinding wheel 8, and the pressure difference indicated by the front and rear pressure sensors 24.25 during grinding. Similarly, the ratio between the pressure difference indicated by the right and left pressure sensors 20 and 21 during grinding is determined. In this case as well, as the grinding wheel 8 wears, the pressure difference indicated by the front and rear pressure sensors 24, 25 increases, and the pressure difference indicated by the right and left pressure sensors 20, 21 decreases, so the difference in meat pressure increases. It can be assumed that the ratio also changes as the grindstone 8 wears. The ROM 31 also stores values for the ratio when not in use and at the wear limit, and the CPU 29
determines where the obtained ratio is between the ratio when not in use and the ratio when at the wear limit, and displays it on the numerical display section 26a of the display panel 26. Then, as in the case described above, the user closes this display and determines whether or not a dressing operation or the like is necessary. As mentioned above, the reason why the material of the workpiece W, depth of cut, workpiece feed speed, and grindstone rotation speed are set to predetermined values is that these factors affect the ratio of the principal force F1 and the thrust force F2. This is because an error occurs in the application determination result, and the reason why the ratios stored in the ROM 31 are used depending on the type of grindstone to be measured is because the ratios differ depending on the grindstones 8. As described above, according to the wear display device of this embodiment, the grindstone 8
The wear interval is displayed as a numerical value, so even non-experts can easily judge the wear.
2 changes sharply as the grindstone 8 wears, so it is possible to grasp the wear state of the grindstone 8 extremely accurately and early. Therefore, the wear of the grindstone 8 is not noticed too late, and the workpiece W does not continue to be ground with the grindstone 8 that has become worn. In addition, in the wear display device of this embodiment, upper and lower pockets 14.15 and front and rear pockets 16.1
Since the hydraulic pressure of grinding wheel 8 and 7 is detected respectively,
The amount of wear on the outer circumferential surface and side surface of the grindstone 8 can be displayed, allowing the user to grasp the wear state of the grindstone 8 more accurately. In this embodiment, the wear detection device of the present invention is embodied as a display device that displays the amount of wear on the grindstone 8, but the wear detection device of the present invention is not limited to this, and for example, the wear detection device of the present invention is
It is embodied as a wear detection device that determines the amount of wear on the grinding wheel in an O-grinding machine, and based on the judgment value of the device, the NG grinding machine automatically takes predetermined measures, such as notifying the administrator with a buzzer, The dressing process may be performed automatically. With this configuration, the wear state of the grindstone can be automatically managed, and completely unmanned automatic machining can be achieved. Further, although the wear display device of this embodiment uses the grinding wheel 8 of a grinding machine as a grinding wheel, it is not limited to this.
It may also be applied to other cutting tools. In the case of cutting tools such as milling cutters, the ratio of principal force F1 and thrust force F2 is approximately 1:0.3, but even in this case, the principal force F1 and thrust force F2 increase as wear progresses. Since there is a correlation as described in this embodiment between the fluctuation in the pressure and the oil pressure in each pocket, tool wear can be determined based on the oil pressure in each pocket. Furthermore, the wear display device of this embodiment connects pressure sensors 20 to 25 to each pocket 12 to 17 of the static pressure guide section that supports the main shaft 5 of the grinding machine, and detects the wear of the grindstone 8 based on the detected values. However, for example, the pressure sensor may be connected to a pocket of a static pressure guide for reciprocating the table of a grinding machine. In this case, the thrust force F2 accompanying the grinding acts to push down the table, so the thrust force F2 can be determined based on the oil pressure in this pocket. On the other hand, in the wear display device of this embodiment, the discrimination between grinding and idle running is made based on the fluctuation of the oil pressure in the right and left pockets 12 and 13. For example, when the user operates the button during grinding, It is also possible to determine that the time when the CPLJ 29 inputs this signal is the time of grinding. In addition to the normal limit switch for setting the reciprocating stroke of the grinding machine table, it also detects the position where the moving workpiece W contacts the grinding wheel 8 and the position where the workpiece W separates from the grinding wheel 8. A limit switch is provided to
9 may determine when grinding is being performed. In addition, in the wear display device of this embodiment, thrust force F2
Upper and lower pressure sensor + J22.23 to estimate
Although the front and rear pressure sensors 24 and 25 are provided, only one of them may be used. For example, if only the upper and lower pressure sensors 22 and 23 are provided, the wear of the outer circumferential surface of the grinding wheel 8 may be reduced. The amount of wear can be measured by grinding. Furthermore, in the wear display device of this embodiment, the principal force F1 is determined from the pressure difference in the right and left pockets 12 and 13, and the principal force F1 is determined from the pressure difference in the upper and lower pockets 14 and 15, or the front and rear sides. Although the thrust force F2 was determined from the pressure difference in the pockets 16 and 17, it is not necessary to determine the respective pressure differences. For example, the principal force F2 is determined based on the oil pressure in the upper pocket 14, and The thrust force F2 may be determined based on the oil pressure in the engine 12. Furthermore, since the oil pressure in all the pockets 12 to 17 increases and decreases as the grinding wheel 8 wears, if it is known in advance how the oil pressure in a particular pocket changes as the grinding wheel 8 wears, It is also possible to determine the wear of the grindstone 8 based only on the oil pressure in the pocket. Therefore, for example,
The wear of the grindstone 8 may be determined based only on the oil pressure in the right side pocket 12. [Effects of the Invention] As detailed above, according to the tool wear detection device of the present invention, tool wear can be detected early without requiring skill from the user, and machining can be performed with a defective tool. It has the excellent effect of not only preventing problems from occurring, but also being able to handle improvisational measurements for unmanned automatic machining.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of the grinding machine showing the spindle head and display plate, Fig. 2 is a side sectional view of the spindle head, Fig. 3 is a block diagram showing the return air configuration, and Fig. 4 is a grinding wheel and An explanatory diagram showing the principal force and thrust force generated between the grinding wheel and the workpiece, Figure 5 is an explanatory diagram showing the thrust force generated between the grindstone and the workpiece, and Figure 6 is the pressure accompanying the reciprocating movement of the grindstone. FIG. 7 is an explanatory diagram showing changes in the detected value of the sensor, and FIG. 7 is an explanatory diagram showing changes in the principal component force and thrust component force due to wear of the grindstone. 8 is a grindstone as a tool, 12.13 is a right and left pocket as a first static pressure guide, and 13 to 17 are upper, lower, front, and rear pockets as a second static pressure guide. , 20.21 are right and left pressure sensors as first detection means, 22 to 25 are upper, lower, front, and rear side pressure sensors as second detection means, and 29 is CPU, w as determination means. is the workpiece, Fl is the main valve], and F2 is the thrust force. Patent applicant Nagase Iron Works Co., Ltd. Agent Patent attorney On 1) Hironobu 116 Figure 17wJ Voluntary procedure 1n Original details Zan June 29, 1999 1, Indication of case Patent application No. 332675 of 1988 2 , Name of the invention: Tool wear detection device 3, Relationship with the person making the amendment: Patent applicant Address: 1, 1333 Atobe, Mugiyo-cho, Mugi-gun, Gifu Name: Nagase Iron Works Co., Ltd. (Name) Representative: Noboru Nagase 4, Agent address: 2 Hatazume-cho, Gifu City, 500 Japan <0582> 65-1810 (Representative) Fax only <0582> 66-13396, Contents of amendment 1, Name of invention Wear detection device for workers and wear detection Method 2, claim 1, is connected to a static pressure guide part (12 to 17) for relatively moving the tool (8) and workpiece (W) in a processing machine, and detects the hydraulic pressure at the same location. Pressure detection means (20-2
5), and a static pressure guide section (1) indicated by the pressure detection means (20 to 25).
2 to 17)) A tool wear detection device comprising: determination means (29) for determining the amount of wear of the tool (8) based on the oil pressure of items 2 to 17). 2. Among the static pressure guide parts (12 to 17) for relatively moving the tool (8) and the workpiece (W) in the processing machine,
A first pressure detection means (20, 21) is connected to the first static pressure guide part (12, 13) to which the main component force (F1) of the grinding resistance is applied during machining, and detects the hydraulic pressure at the same location. , Similarly, among the static pressure guide parts (12 to 17) of the processing machine, the second static pressure guide part (14 to 17) to which the thrust force (F2) of the grinding resistance is applied during machining, is connected to the hydraulic pressure at the same location. second pressure detection means (22 to 25) that detects the hydraulic pressure of the first static pressure guide section (12, 13) indicated by the first pressure detection means (20, 21); Second static pressure guide section (14-17) indicated by detection means (22-25)
A tool wear detection device comprising a determination means (29) for determining the amount of wear of the tool noodle (8) based on the oil pressure of the tool. 3. A tool wear detection method that determines the wear amount of the worker (8) based on the oil pressure of the static pressure guide portion (12 to 17) in the processing machine. 3. Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a tool wear detection device and a wear detection method. Conventional technology] In general, tool abnormalities in processing machines, such as abrasion and chipping in cutting tools such as milling cutters, and wear, clogging, and denting (grinding) in grinding tools such as whetstones, are common.
, below, collectively referred to as wear), it adversely affects the machined surface of the workpiece. Traditionally, operators judge tool wear based on the workpiece after machining. For example, in the case of a grinding wheel, when the workpiece surface becomes rough, grinding burns, etc. occur, or when the amount of cut during grinding occurs. However, when there is little change in the dimensions of the actual workpiece, it is determined that the grindstone is worn out, and the grindstone is dressed or replaced. [Problem to be Solved by the Invention 1] However, as mentioned above, not only does it require considerable skill to judge the amount of wear on the grindstone, but it also requires a certain amount of skill to judge the amount of wear on the grindstone. and wear cannot be determined. Therefore, by the time the operator grasps the situation and takes action, there is a problem that a considerable amount of grinding has already been done with a grindstone that is already worn out. This applies not only to grinding wheels but also to all types of machining shells. The above-mentioned problems occur particularly in the case of unmanned automatic machining, and even though the machining process is automated, the current situation is that tool wear cannot be automatically managed. For this reason, there is a demand for the development of in-process measurement that achieves complete automation and unmanned operation. The purpose of the present invention is to be able to detect tool wear early without requiring the user to be skilled, to prevent machining with defective tools, and to support in-process measurement for unmanned automatic machining. An object of the present invention is to provide a tool wear detection device and a tool wear detection method that can perform the following steps. [Means for Solving the Problems] A first invention includes a pressure detection means connected to a static pressure guide for relatively moving a tool and a workpiece in a processing machine, and detecting oil pressure at the same location; The gist of the present invention is a tool wear detection device comprising a determination means for determining whether the tool is worn out based on the hydraulic pressure of the static pressure guide section, which is not indicated by the pressure detection means. The second invention is connected to the first static pressure guide part to which the main force of the grinding resistance is applied during machining, among the static pressure guide parts for relatively moving the tool and the workpiece in the processing machine, and the same A first pressure detection means for detecting the hydraulic pressure at a location is connected to a second static pressure guide section of the static pressure guide section of the processing machine to which the force of the grinding resistance is applied during machining, and the hydraulic pressure at the same location is a second pressure detection means for detecting the pressure, a hydraulic pressure of the first static pressure guide section indicated by the first pressure detection means, and a hydraulic pressure of the second static pressure guide section indicated by the second pressure detection means. Based on the above, the gist of the present invention is to provide a tool wear detection device comprising a determination means for determining the amount of wear on the tool. The gist of the third invention is a tool wear detection method for determining the amount of tool wear based on the hydraulic pressure of a static pressure guide in a processing machine. [Function] In the first invention, when the tool wears and becomes dull, the hydraulic pressure of the static pressure guide section to which this resistance is applied changes as the machining resistance increases or decreases. The determination means determines the amount of wear on the tool based on the hydraulic pressure of the static pressure guide detected by the pressure detection means. In the second invention, when the tool wears and becomes dull, the principal force of the machining resistance decreases and the thrust force increases. As the main force decreases, the oil pressure of the first static pressure guide to which this force is applied decreases or increases, and as the thrust force increases, the oil pressure of the second static pressure guide to which this force is applied increases or decreases. do. The determination means detects the tool based on the oil pressure of the first static pressure guide detected by the first pressure detection means and the oil pressure of the second static pressure guide detected by the second pressure detection means. Determine the amount of wear. In the third invention, when the tool wears and becomes dull, the hydraulic pressure of the static pressure guide section to which this resistance is applied changes as the machining resistance increases or decreases. Therefore, it is possible to determine whether the tool is worn out based on the hydraulic pressure of the static pressure guide. [Example] Hereinafter, an example in which the present invention is embodied in a wear display device for a grinding wheel of a grinding machine will be described with reference to the drawings. As shown in FIG. 1, a spindle 2 that can move up and down within a column 1 of a grinding machine is provided with a main spindle head 3 so as to protrude forward, and a bearing sleeve 4 is fitted into the main spindle head 3. There is. A holding hole 4 provided through the bearing sleeve 4
The large diameter portion 5a of the main shaft 5 is rotatably inserted into the sleeve 4, and front and rear covers 6.7 are attached to the front and rear of the sleeve 4.
are opposed to the step portions 5b formed on both sides of the large diameter portion 5a, and stop the movement of the main shaft 5 in the axial direction with respect to the bearing sleeve 4. A grindstone 8 as a tool is attached to the front end of the main shaft 5, and the rear end is connected via a coupling 10 to a motor 9 for driving the grindstone provided on the spindle 2. As shown in Figure 1.2, the outer periphery of the main shaft 5 and the holding hole 4
There is a fine gap 11 between the inner circumferential wall of a for static pressure guidance.
This gap 11 is also formed between the stepped portion 5b of the main shaft 5 and the front cover 6 and rear cover 7, respectively. In addition, right and left pockets 12 and 13 and upper and lower pockets 14 and 15 for static pressure guidance are provided at equal intervals on the inner circumferential wall of the holding hole 4a at the front and rear parts thereof, respectively. Front and rear cover 6゜7
Also provided are annular front and rear pockets 16, 17, respectively. An oil supply path and an oil recovery path (not shown) are connected to each of the pockets 12 to 17, and the hydraulic oil in the oil tank is supplied to each pocket 12 to 17 via the oil supply path by an oil pump.
After being pumped into the oil tank 17, the oil is collected into an oil tank via an oil recovery path. The right and left pockets 12.13 are used as first static pressure guide parts, and the upper and lower pockets 14.15 and the front and rear pockets 16.17 are respectively used as second static pressure guide parts. The hydraulic oil supplied into each of the pockets 12 to 17 fills the pockets 12 to 17 and forms an oil film in each gap 11. Therefore, the main shaft 5 is connected to the bearing sleeve 4.
is held in the holding hole 4a via an oil film, and
The grindstone is rotated clockwise by a motor 9 for driving the grindstone. The right, left, upper, and lower pockets 12 to 5 on the front side of the holding hole 4a open to the outer periphery of the flange of the bearing sleeve 4 via an oil pressure detection path 18, and each opening has a coupler 19. is screwed in. Right and left pressure sensors 20.21 as first pressure detection means are removably connected to the cover 19 communicating with the right and left pockets 12.13, respectively.
Coupler 19 communicating with upper and lower pockets 14°15
Upper and lower pressure hinges 22 and 23 as second pressure detection means are removably connected to the respective pockets 12 to 15 to detect the hydraulic pressure in the respective pockets 12 to 15. The front pocket 16 opens on the outer periphery of the front cover 6 via an oil pressure detection path 18, and the rear pocket 17 opens on the outer periphery of the flange of the bearing sleeve 4 via an oil pressure detection path 18. Front and rear pressure sensors 24.25 as second pressure detection sensors are detachably connected to the screwed cover 19 to detect the oil pressure in each pocket 16.17. As shown in FIG. 1.2, each of the pressure sensors 20 to 25
is connected to a display W26, and on the front surface of the display panel 26 is provided a display section 26a composed of an LED for displaying the wear state of the grindstone, and below the display section 26a is a display section 26a for measuring the wear amount of the grindstone 8. A grindstone specification dial 27 and a power switch 28 are provided for specifying the type of grindstone. As shown in FIG. 3, each of the lenses 20 to 25 and a grindstone designation dial 27 are connected to a central processing unit (hereinafter referred to as CPU) 29 installed in the display panel 26, and a display section 26a are connected via a display unit drive circuit 32. Further, a random access memory (hereinafter referred to as RAM) 30 and a read only memory (hereinafter referred to as ROM) 31 are connected to the CPU 29, and RO
The M31 stores a program for determining whether the grindstone 8 is grinding the workpiece W and a program for determining the amount of wear on the grindstone 8, and the CPU 29 operates to display the amount of wear according to these programs. It is now possible to do this. Note that the RAM 30 is designed to temporarily store data for processing performed by the CPU 29. Next, we will describe the operation of the wear display device configured as described above, but before that, we will explain how the grinding resistance generated during grinding affects the oil pressure in each of the pockets 12 to 17. do. Needless to say, no grinding resistance is generated during idle running when the grindstone 8 separates from the workpiece W as the workpiece W reciprocates in the left-right direction. For this reason, the grindstone 8 and the main shaft 5 that supports it
Since no grinding resistance is applied to the gaps 11, all of the gaps 11 are uniform, and the resistance when the hydraulic oil flows from inside each pocket 12 to 17 to the oil recovery path through the gap 11 is equal. The pressure inside 17 is also all equal. As shown in FIG.
When grinding, the thrust force F2 of the grinding resistance is applied to the grinding wheel 8.
This thrust force F2 also extends to the main shaft 5 supporting the grindstone 8. As a result, the gap 11 near the upper pocket 14 becomes narrower, making it difficult for the hydraulic oil that has flowed into the upper pocket 14 to be discharged to the oil recovery path, thereby increasing the oil pressure within the pocket 14. Also,
On the contrary, the gap 11 near the lower pocket 15 becomes wider, so that the hydraulic oil that has flowed into the lower pocket 15 is easily discharged to the oil recovery path, and the oil pressure in the pocket 15 decreases. Therefore, a pressure difference is generated between both pockets 14 and 15, and this pressure difference increases or decreases in accordance with the magnitude of the thrust force F2 applied to the grindstone 8. Furthermore, when the grindstone 8 is grinding the workpiece W on its side surface, the thrust force F2 of the grinding resistance acts to move the grindstone 8 to the side opposite to the cutting direction (backward in Figure I35). As in the case described above, the oil pressure in one of the front and rear pockets 16, 17 increases while the other oil pressure decreases. For this reason, both pockets 16.1
A pressure difference is generated between the wheels 7 and 7, and the pressure difference in this case also increases or decreases in accordance with the magnitude of the thrust force F2 applied to the grindstone 8. On the other hand, as shown in FIG. 4, since the grindstone 8 rotates clockwise during any of the grinding operations described above, the main force F1 of the grinding resistance acts to move the grindstone 8 to the right. Therefore, during grinding, the oil pressure in the right pocket 12 always increases while the oil pressure in the left pocket 13 decreases, and both pockets 12
．． A pressure difference occurs at 13. The pressure difference in this case increases or decreases in accordance with the magnitude of the principal force F1 applied to the grindstone 8. Generally, the ratio of the principal force F1 of the grinding resistance to the thrust force F2 takes a value of about 1:1.5 to 1:2.5, and this value changes as the grinding wheel 8 wears out. That is, when a back force is generated by grinding a certain cutting edge, a principal force corresponding to the amount of wear of the grindstone 8 at this point in time is generated. For example, as shown by the broken line in FIG. 7, an unused grindstone 8 has good sharpness, so the ratio of the principal force F1 to the back force F2 is large. When the sharpness deteriorates due to wear, the principal force F1 decreases and the thrust force F2 increases, reaching the wear limit shown by hatching in FIG. In this way, when the grinding wheel 8 wears out, the principal force F1 and the thrust force F
2 increases or decreases, and the oil pressure in each of the pockets 12 to 17 changes. Therefore, the wear of the grindstone 8 can be determined based on the oil pressure in each of the pockets 12 to 17. Therefore, assuming that the above phenomenon occurs,
A case in which the wear of the grindstone 8 is measured using this wear display device will be described in detail. First, the type of grindstone 8 whose wear amount is to be measured is determined from the display panel 2.
Grinding wheel 8 is specified using Daicel 27, and grinding is started on a work W of a predetermined material at a predetermined cutting depth, workpiece feed speed, and grindstone rotation speed. Activate the power switch 28. Then, as shown in FIG.
The detected value of is synchronized with the reciprocating movement of the workpiece W, and alternately repeats a certain pressure value and a pressure value higher by a predetermined amount than that value, and the detected value of the left pressure sensor 21 is the same pressure value as the right pressure sensor 20. A pressure value lower than that by a predetermined amount is alternately repeated. The CPLJ 29 inputting this detection signal determines that when there is a pressure difference, it is the time of grinding ilQ, and when there is no pressure difference, it determines that it is the time of idle running when the grindstone 8 is separated from the workpiece W. As mentioned above, during grinding, a pressure difference always occurs between the right and left pockets 12, 13, and when running idle, both pockets 12.
．． 13, the time when the right and left pressure hinges 20 and 21 detect a pressure difference can be regarded as the time of grinding, and the time when no pressure difference is detected can be considered as the time of idle running. . Next, the CPU 29 determines which of the pressure difference indicated by the upper and lower pressure sensors 22.23 and the pressure difference indicated by the front and rear pressure sensors 24.25 is larger during grinding. As mentioned above, the upper and lower pressure sensors 22,2
3 indicates a large pressure difference, the front and rear pressure hinges 24
．． 25 shows almost no pressure difference, it can be assumed that grinding is being carried out on the outer peripheral surface of the grindstone 8. On the contrary, the upper and lower pressure sensors 22 and 23 show almost no pressure difference, and the front and When the rear pressure sensors 24 and 25 indicate a large pressure difference, it can be assumed that grinding is being performed on the side surface of the grindstone 8. For example, if the upper and lower pressure sensors 22.23 indicate a large pressure difference, the CPU 29 determines that grinding is being performed by the outer peripheral surface of the grindstone 8, and the upper and lower pressure sensors 22.23 indicate that the The ratio between the pressure difference and the pressure difference indicated by the right and left pressure sensors 20 and 21 during grinding is determined. As described above, as the grindstone 8 wears, the pressure difference indicated by the upper and lower pressure sensors 22 and 23 increases, and the pressure difference between the stone and left pressure sensors 20.
Since the pressure difference indicated by 21 becomes smaller, it can be assumed that the ratio of the difference between the two positive forces also changes as the grindstone 8 wears. The ROM 3i stores the ratio of each grindstone 8 that can be selected with the fJ1EJ designation dial 27 when it is not in use and at the wear limit, and the CPU 29 stores the calculated ratio. The position between the ratio when not in use and the ratio at the limit of wear stored in the ROM 31 is determined based on the ratio where the ratio when not in use is 100% and the ratio at the limit of use is 0%. , said display 5? a26
is displayed on the display section 26a. For example, if the grindstone 8 is close to the wear limit, a value close to 0% will be displayed, and the user will need to replace the grindstone 8 or perform a predetermined dressing operation. On the other hand, if the front and rear pressure sensors 24.25 indicate a large pressure difference, the CPU 29 determines that grinding is being performed by the side surface of the grindstone 8, and the pressures indicated by the front and rear pressure sensors 24.25 during grinding. The ratio of the difference to the pressure difference indicated by the right and left pressure sensors 20, 21 during grinding is determined. In this case, as the grinding wheel 8 wears out, the pressure difference between the front and rear pressure sensors 24 and 25 increases, and the pressure difference between the right and left pressure sensors 20 and 21 decreases, so both positive It can be assumed that the ratio of the difference also changes as the grindstone 8 wears. The ROM 31 also stores the values of the ratio when unused and at the wear limit, and the CPU 29 determines which ratio the calculated ratio is between the ratio when unused and the ratio at the wear limit. It is determined whether it is in the position or not, and the result is displayed on the numerical display section 26a of the display panel 26. Then, as in the case described above, the user determines whether a dressing operation or the like is necessary based on this display. As mentioned above, the reason why the material of the workpiece W, depth of cut, workpiece feed speed, and grindstone rotation speed are set to predetermined values is that these factors affect the ratio of the principal force F1 and the thrust force F2. This is because an error occurs in the application determination result, and the reason why the ratios stored in the ROM 31 are used depending on the type of grindstone to be measured is because the ratios differ depending on the grindstones 8. In this way, according to the wear display device of this embodiment, since the amount of wear on the grinding wheel 8 is displayed as a numerical value, even an unskilled person can easily judge the wear. E2
Since the ratio between the
The wear state of the grindstone 8 can be determined extremely accurately and quickly. Therefore, the wear of the grindstone 8 is not noticed too late, and the workpiece W does not continue to be ground with the grindstone 8 that has become worn. In addition, in the wear display device of this embodiment, upper and lower pockets 14.15 and front and rear pockets 16.1
Since the hydraulic pressure of grinding wheel 8 and 7 is detected respectively,
The amount of wear on the outer circumferential surface and side surface of the grindstone 8 can be displayed, allowing the user to grasp the wear state of the grindstone 8 more accurately. Note that this embodiment uses the wear detection device of the present invention. Although the wear detection device of the present invention is embodied as a display device that displays the amount of wear of i8, the wear detection device of the present invention is not limited to this, and for example,
It is embodied as a wear detection device d that determines the amount of wear on the grinding wheel in an NC grinding machine, and based on the judgment value of the device, the NG grinding machine side automatically takes a predetermined action, for example, notifies the administrator with a brake. Alternatively, the dressing process may be performed automatically. With this configuration, the wear state of the grindstone can be automatically managed, and completely unmanned automatic machining can be achieved. Further, although the wear display device of this embodiment was intended for the grinding wheel 8 of a grinding machine, it is not limited to this.
It may also be applied to other cutting tools. In the case of cutting tools such as milling cutters, the ratio of principal force F1 and thrust force F2 is approximately 1:0.3, but even in this case, the principal force F1 and thrust force F2 increase as wear progresses. Since there is a correlation as described in this embodiment between the fluctuation in the pressure and the oil pressure in each pocket, tool wear can be determined based on the oil pressure in each pocket. Roughly speaking, the wear display device of this embodiment connects pressure sensors 20 to 25 to each pocket 12 to 17 of the static pressure guide that supports the main shaft 5 of the grinding machine, and adjusts the grinding wheel 8 based on the detected values. Although wear has been determined, the pressure sensor may, for example, be connected to a pocket of a static pressure guide for reciprocating the table of a grinding machine. In this case, the thrust force F2 accompanying the grinding acts to push down the table, so the thrust force F2 can be determined based on the oil pressure in this pocket. On the other hand, in the wear display device of this embodiment, the discrimination between grinding and idle running is made based on the fluctuation of the oil pressure in the right and left pockets 12 and 13. For example, when the user operates the button during grinding, The CPU 29 may determine that the time when this signal is inputted is the time of grinding. Also,
In addition to the normal limit switch for setting the reciprocating stroke of the table of the grinding machine, there is also a limit switch for detecting the position where the moving workpiece W contacts the grinding wheel 8 and the position where the workpiece W separates from the grinding wheel 8. A limit switch is provided, and based on the on/off of this limit switch, the CPU 29
Alternatively, the grinding time may be determined. In addition, in the wear display device of this embodiment, thrust force F2
Although the upper and lower pressure sensors 22, 23 and the front and rear pressure sensors 24, 25 are provided in order to estimate the If provided, it is possible to grind the outer circumferential surface of the grindstone 8 and measure the wear distance. Furthermore, in the wear display device of this embodiment, the principal force F1 is determined from the pressure difference in the right and left pockets 12 and 13, and the principal force F1 is determined from the pressure difference in the upper and lower pockets 14 and 15, or the front and rear sides. Although the thrust force F2 was determined from the pressure difference in the pockets 16 and 17, it is not necessary to determine the respective pressure differences. For example, the principal force F2 is determined based on the oil pressure in the upper pocket 14, and The thrust force F2 may be determined based on the oil pressure in the engine 12. Furthermore, since the oil pressure in all the pockets 12 to 17 increases and decreases as the grinding wheel 8 wears, if it is known in advance how the oil pressure in a particular pocket changes as the grinding wheel 8 wears, It is also possible to determine the wear of the grindstone 8 based only on the oil pressure in the pocket. Therefore, for example,
The wear of the grindstone 8 may be determined based only on the oil pressure in the right side pocket 12. [Effects of the Invention] As detailed above, according to the tool wear detection device and the tool wear detection method of the present invention, tool wear can be detected early without requiring the user to be skilled, and defective tools can be detected. It has the excellent effect of preventing machining in advance and also supporting in-process measurement for unmanned automatic machining.

[Brief explanation of the drawing]

Figure 1 is a partial sectional view of the grinding machine showing the spindle head and display plate, Figure 2 is a side sectional view of the spindle head, Figure 3 is a block diagram showing the electrical configuration, and Figure 4 is the grinding wheel and workpiece. Fig. 5 is an explanatory diagram showing the principal force and thrust force generated between the grinding wheel and the workpiece, Figure 5 is an explanatory diagram showing the thrust force generated between the grinding wheel and the workpiece, and Fig. 6 is a pressure sensor accompanying the reciprocating movement of the grinding wheel. FIG. 7 is an explanatory diagram showing changes in the detected value of , and FIG. 7 is an explanatory diagram showing changes in the principal component force and thrust component force due to wear of the grindstone. 8 is a grindstone as a tool; 12.13 is a right and left pocket as a first static pressure guide; 13 to 17 are upper, lower, front, and rear pockets as a second static pressure guide; 20. 21 are right and left pressure sensors as first detection means, 22 to 25 are upper side as second detection means,
Lower side, front side, and return side pressure sensors, 29 are Cpu as a determination means, w is a workpiece, Fl is a principal component force, and F2 is a thrust component force.

Claims (1)

[Claims] 1. Pressure connected to the static pressure guide section (12 to 17) for relatively moving the tool (8) and workpiece (W) in the processing machine and detecting the hydraulic pressure at the same location. Detection means (20-2
5), and a static pressure guide section (1) indicated by the pressure detection means (20 to 25).
2 to 17)) A tool wear detection device comprising: determination means (29) for determining the amount of wear of the tool (8) based on the oil pressure of items 2 to 17). 2. Among the static pressure guide parts (12 to 17) for relatively moving the tool (8) and the workpiece (W) in the processing machine,
The first pressure detection means (20, 21) is connected to the first static pressure guide section (12, 13) to which the main component force (F1) of the grinding resistance is applied during machining, and detects the hydraulic pressure at the same location. Among the static pressure guide parts (12 to 17) of the processing machine, it is connected to the second static pressure guide part (14 to 17) to which the thrust force (F2) of the grinding resistance is applied during machining, and the hydraulic pressure at the same point is detected. second pressure detection means (22 to 25), the hydraulic pressure of the first static pressure guide section (12, 13) indicated by the first pressure detection means (20, 21), and a second pressure detection means The second static pressure guide section (14-17) indicated by (22-25)
A tool wear detection device comprising a determination means (29) for determining the amount of wear of the tool (8) based on the oil pressure of the tool.