JPH02237766A - Method and device for controlling dressing of grinding grindstone - Google Patents

Abstract

PURPOSE:To properly decide a dressing start time and to make the accuracy of a grinding face constant by measuring a force acting between a work and grinding grindstone during grinding and performing dressing at the time when this value becomes larger than a set value. CONSTITUTION:A grinding resistance acting between a work 1 and grindstone 7 is detected by a grinding resistance detecting element 10 and fed to an arithmetic circuit 21 via an amplifier 19. This arithmetic circuit 21 compares the measured value of the grinding resistance fed from the amplifier 19 with the upper limit and lower limit values of the allowable value of the grinding resistance preset to a setter 20, feeding this result to a numerical control device 22. This numerical control device 22 gives a command to a motor 17 via a motor control circuit 23 by a preinput program and this result, subjecting the grinding grindstone 7 to this dressing by operating a dressing device 14 when the measured value exceeds the upper limit value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dressing control method for a grinding wheel 4 and an apparatus thereof.

[Conventional technology]

The skill of dressing the grinding wheel greatly affects the sharpness of the grinding wheel. Therefore, for example,
No. 5550 or Japanese Patent Application Laid-Open No. 62-203759 discloses a method of finishing dressing by focusing on the RTC force acting between the dresser and the grinding wheel during dressing and using this as a criterion.

These techniques allow even unskilled workers to maintain the sharpness of the grinding wheel and shorten the dressing time.Furthermore, it is possible to set the dressing cycle in advance. This made it possible to automate the grinding process.

[Problem to be solved by the invention]

However, in order to make the above-mentioned dressing cycle appropriate, the skill level of the operator is required. In other words, if the dressing cycle is set too long, the cutting force of the grinding wheel will be reduced and work efficiency will be lowered, and if the dressing cycle is too short, unnecessary dressing will be missed. , similarly, work efficiency decreases.

The object of the present invention is to provide a dressing control method and apparatus for a grinding wheel that can solve the above-mentioned problems and appropriately determine the entire dressing cycle. ．． In addition to improving work efficiency,
〈 All work is fully automated.

[Unfortunate means to solve the problem]

The above problem can be solved by measuring the force acting between the workpiece and the grinding wheel during grinding and comparing the measured value with the caulking setting value.

[For production]

When the value of the force between the workpiece and the grinding wheel exceeds a preset value, that is, the grinding wheel becomes dull and must be dressed. Therefore, when the measured value exceeds a preset value, the dressing cycle becomes optimal.

〔Example〕

Embodiment 1 of the present invention will be explained below with reference to FIGS. 1 to 4.

FIG. 1 is a front view of a surface grinding machine J to which a grinding wheel dressing control device according to the present invention is applied.

In the same figure, 2 is a bed. A column 3 is placed on the bed 2 so as to be movable in the horizontal direction in the figure, and is driven by a motor 4. Reference numeral 5 denotes a spindle head, which is held so as to be movable in the vertical direction in the column 3K, and is driven by a motor 6. Reference numeral 7 denotes a super-abrasive grindstone (hereinafter referred to as a grindstone), which is rotatably held by the spindle head 5 and rotated by a motor (not shown). A table 8 is placed on the bed 2 so as to be movable in a direction perpendicular to the plane of the paper, and is driven by a hydraulic cylinder (not shown). Reference numeral 9 denotes a chuck, which is fixed to the table 8 via a grinding resistance detecting element 10 made of a pressure-mechanical element. A workpiece 11 is attached to the chuck 9. Reference numeral 12 is fixed to the bed 2 by a proximity switch, and fixed to the column 3 by a dog 134''. Reference numeral 14 is a dressing device, and its body 15 is fixed on the spindle head 5.

Reference numeral 16 denotes a dresser head, which is held by the main body 15 so as to be slidable in the vertical direction in the figure, and is driven by a motor 17. Reference numeral 18 denotes a cup-shaped dressing grindstone (hereinafter referred to as "dresser" 5) made of A-based abrasive grains or C-based abrasive grains, which is rotatably held by the dresser head 16 and rotated by a motor (not shown).

19 is an amplifier for the grinding resistance detection element 10; Reference numeral 20 denotes a setting device for setting and storing the upper limit Fu and lower limit Ft of the allowable value of the grinding resistance acting between the grinding wheel 7 and the workpiece 11.

21 indicates the upper limit value Fu and lower limit value Ft set in the setting device 20 and the measured value Fa of the grinding resistance output from the amplifier 19.
An arithmetic circuit that compares and determines the magnitude relationship between Reference numeral 22 denotes a numerical control device that controls the movement of the surface grinding machine 1 according to the calculation results from the calculation circuit 2 1 K and a separately inputted program. 23
is a control circuit for the motor 17. 24 is a control circuit for controlling drive systems other than the motor 17.

In the above configuration, the plane cutting machine 1 has a numerical control device 22.
According to the commands shown in the figure, the table 8 is moved vertically on the paper, the column 3 is moved left and right, the spindle head 5 is moved up and down, and the grindstone 7 is rotated, and the workpiece 11 is ground by the grindstone 7. .

Furthermore, since the dressing device 14 uses the dresser 18 made of a cup-shaped grindstone, the dressing device 14 can be dressed by simply feeding the dressing heads 1 and 6 toward the grindstone 7 while rotating the dresser L81. It has become. That is, the dressing device 14 is an infeed type dressing device. The operation will be explained below.

The signal is constantly detected by the child 10 and sent to the arithmetic circuit 21 via the amplifier 19. The arithmetic circuit 21 compares the specified value F& of the grinding resistance sent from the amplifier 19 with the upper limit value pu and lower limit value Ft of the allowable value of the grinding resistance preset in the setting device 20, and transmits the result to the numerical control iron. Send to station 22. The numerical control device 22 gives commands to the motor 17 via the nine motor control circuit 23ft based on this result and the program input in advance, and controls the entire dressing cycle by the method described below.

Here, FIGS. 2 (Todoroki) and (b) show the positional relationship between the workpiece 11 and the grindstone 7 in creep feed grinding, and the changes in the grinding resistance at this time. In addition,
As shown in FIG. 1, for the sake of clarity, the grindstone 7 is shown moving to provide grinding feed. Since creep feed grinding is a grinding method characterized by deep cutting and low speed feed, the state of interference between the workpiece 11 and the grindstone 7 changes near the start of grinding and near the end of grinding. That is, as shown in FIG. 3A, the grinding wheel 7 starts its full feeding movement from position A, and when it reaches the position opening, it comes into contact with the workpiece 11 and grinding begins. As the position progresses from position C to position 2, the contact point where the grinding wheel 7 and workpiece 11 interfere is 4 to 4. The length of the contact arc (the hatched part in the figure) is the next younger brother rc-AJ.
4, the grinding resistance changes at a constant value as shown by the two-dot chain line in FIG. 4(b). However, in reality, the whetstone 7
As the sharpness of the blade deteriorates, the grinding resistance increases as shown by the solid line in FIG. 2(b). Since the length of the contact arc gradually decreases from position E to position T, the grinding resistance decreases to 0 at position T. The increase in grinding resistance from position 2 to position E is quite large when using difficult-to-rigid materials such as fine ceramics, and dressing is often required in the middle.

Figure 3 shows the 7 rotors of the dressing cycle in this case, and Figure 4 shows how the grinding resistance changes when the control shown in Figure 3 is carried out.
Ru. The arithmetic circuit 21 is not powered at all times. Therefore, in FIG. 4, the area between A and B is not dressed. When it comes to B, it becomes F
Since a≧Fu, a signal is output from the arithmetic circuit 21, and numerical control! [22 operates the motor 17 to perform dressing/cutting, and continues dressing cutting during Fa)Ft. Therefore, the sharpness of the grindstone 7 gradually recovers, and the grinding resistance decreases from B to C. By turning GK, the grinding resistance changes within the range between the upper limit value Fu and the lower limit value Ft like CH, and the stable sharpness of the grindstone 7Fi can be maintained.

The second embodiment of the present invention will now be explained with reference to FIG. 1 and FIGS. FIG. 5 shows how the grinding resistance changes when plunge grinding shown in FIG. 8 C &) is performed. In this case, since the grinding process is performed by reciprocating the table 8't-kneading, the grinding resistance is detected in a cycle of increasing from 0 and returning to 0 for each pass of the table 8. In addition, in the case of normal grinding, the depth of cut is shallow and the feed rate is high, so the grinding resistance does not change depending on the positional relationship between the grinding wheel 7 and the workpiece 11, as in the case of creep feed grinding shown in Fig. 2. It can be considered that there are almost no such cases. However, due to the action of the grinding resistance, elastic displacement occurs between the grinding wheel 7 and the workpiece 11.
For a while after the start of cutting, the actual depth of cut becomes smaller than the set depth of cut 1, so the value of the grinding resistance also becomes small and gradually increases until it reaches a steady value. If the sharpness of the stone does not change, the grinding resistance will remain at a constant value as shown by the two-dot chain line in the figure, but in reality, the sharpness of the stone will deteriorate as the grinding process continues. The grinding resistance gradually increases as shown by the solid line.

In this case as well, it is possible to constantly detect and control the grinding resistance as shown in FIG. It can happen. Therefore, here, the maximum value Fm of the grinding resistance for each pass of table 8 is
ax:i Calculated by the arithmetic circuit 21, this maximum value F'max and the upper limit Fu set in the setting circuit 20 and lower w4: @F
By comparing t and t, the dressing cycle is controlled. The measurement time range of the grinding resistance for calculating the maximum value Frnax of the grinding resistance can be determined using the return signal of the table 8. FIG. 6 shows the flow rate in this case, and FIG. 7 shows how the grinding resistance changes when controlled in this way.

The arithmetic circuit 21 calculates the maximum value pmax. Find f, compare it with the upper limit value Fu set in the setting device 20, and find F
If maX<Fu, no signal is output. Therefore, the seventh
The area between A and B in the figure is not dressed. When it comes to B, pm
Since ax≧Fu, a signal is output from the arithmetic circuit 21, and the numerical control device 22 operates the motor 7 to start dressing cutting. From this point on, the arithmetic circuit 21 compares the maximum value Frnax of the grinding resistance with the lower limit value Ft,
pmax , > FA and I am dressing incision t-
continue. Therefore, the grinding resistance gradually decreases. When it comes to C, Fmax≦Ft, so the arithmetic circuit 21
A signal is output from the numerical control device 22Fi motor 7
Stop and complete the dressing cut. and,
The arithmetic circuit 21 returns to the process of comparing the maximum value F'max of the grinding resistance with the upper limit value Fu, and the same operation is repeated thereafter to maintain the sharpness.

Next, the control of the dressing cycle when performing traverse grinding shown in FIG. 8(b) will be explained. The changes in grinding resistance during traverse grinding are roughly shown in P2.
The process is the same as for die grinding, but the following points are different. That is, in the above-mentioned grunge grinding, the grinding width is always constant, but it changes greatly, and even in the middle part, there is generally some fluctuation in the lateral feed amount -4Ft. Even if the sharpness of the whetstone is constant, the sharpness of table 8. A certain amount of variation occurs in the grinding resistance for each bus. ．．
Changes in grinding resistance due to such phenomena are combined with changes in grinding resistance due to deterioration of the sharpness of the grindstone 7, and the change in grinding resistance during traverse grinding is as shown in FIG. 9. In FIG. 9, the pre-polishing resistance is represented by the maximum value for each pass in Table 8. As is clear from FIG. 9, in traverse grinding, even when the sharpness of the grinding wheel 7 has deteriorated, when the grinding width becomes small, the grinding resistance is detected to be small, and the above-mentioned control method does not cause dressing to occur. It can happen. However, since such a state does not continue repeatedly, there is no problem even if the same control as the 7-row chart shown in FIG. 6 is performed in trapper grinding. FIG. 10 shows how the grinding resistance changes when the dressing cycle is controlled according to the flowchart shown in FIG. 6 in the case of traverse grinding. Since the control procedure is the same as in the case of flange grinding, the explanation will be omitted, but it can be seen that the sharpness of the grindstone 8 can be maintained at a satisfactory level.

In this second embodiment, the table 8 values Ft are compared, but the interval of this comparison may be made longer. That is, for example, the number of buses in table 8 may be counted and the comparison may be made every few buses.

Hereinafter, we will explain the third embodiment using FIGS. 1 and 11, taking as an example the case of traverse grinding using normal grinding, similar to the second embodiment described above. :explain.

In this embodiment, the proximity sensor 13 and dog 12 shown in FIG. 1 detect that the column 3 has reached a predetermined position. Then, based on this detection signal, the arithmetic circuit 21
compares the maximum value F'rI1&x of the grinding resistance with the upper limit value Fu or the lower limit value Ft. In this case, the time between comparisons may be longer than in the second embodiment, so that the amount of dressing may become excessive with the control shown in FIG. 6. Therefore, control is performed as shown in FIG. That is, first, the maximum value Fma of grinding resistance:
Find x, compare it with the upper limit Fu, and find Frnax <
If it is Fu, do not dress it. And Fmax≧F
For k of u, preset unit dressing (/
Execute Tsukoikeru. It should be noted that the unit dressing cycle here is one in which the dressing cut is started, and the dressing cut is ended when a preset dressing amount has been applied. Next, the maximum value Fr
Nax is compared with the lower limit value Ft, and a unit dressing cycle is executed M49 times while lmax>Ft.

If li'max≦Ft, the maximum value Fmax and upper limit +i! Returning to the Fu comparison process. Thereafter, by repeating this operation, the sharpness of the grindstone can be maintained in a stable state. In addition, if the grindstone 7 is a super abrasive grindstone, dressing mainly removes the joint cutting part.
The wear of the sailstone 7 due to dressing is slight, and no matter which method shown in the first to third embodiments is used,
The dimensional accuracy of the workpiece 11 is hardly affected.

In the first to third embodiments described above, two controls, dressing interval and dressing proof, can be automatically controlled based on one quantitative value, namely, the grinding resistance value. effective. In addition, since the sharpness of the grindstone remains constant from one grinding wheel to another, it has the effect of stably and highly accurate grinding. Furthermore, since the sharpness of the whetstone is controlled to be maintained at an optimum value, the amount of wear and tear on the whetstone and dresser due to dressing can be kept to a minimum, which also has the effect of providing highly economical dressing. .

In the above embodiment, the grinding resistance was used as a measure to control the dressing interval and dressing amount, but the two-component force ratio (normal grinding resistance and tangential It may also be controlled by the ratio of grinding resistance.

Furthermore, the measurement of the force acting between the grinding wheel 7 and the workpiece 11 is not limited to the grinding resistance;
It is also possible to use physical quantities of each lever excited by the force acting between the two, such as changes in the current and power consumption of the valley motor, and elastic displacement of each part. Further, in the above embodiment, the case where the super abrasive grains and the molten stone 7 are dressed/grilled with the cup-shaped dresser 18 is shown, but the stone and the dresser to be used are not limited to these. In other words, when dressing a grinding wheel made of A-type or C-type fine grains, which reduces the size of the grinding wheel by sheathing, which is different from a superabrasive grinding wheel, with a single diamond, etc., the grinding wheel must be dressed by the amount corresponding to the cutting depth of the dressing. The present invention can be applied by bringing the workpiece closer to the workpiece.

〔Effect of the invention〕

Since the lubricity is indirectly measured and dressing is performed when the value becomes larger than a preset value, it is possible to appropriately determine when to start dressing. Therefore, the precision of the grinding surface remains constant, the work efficiency is improved, and the grinding work can be automated.

Furthermore, by comparing the above-mentioned measured value e6 with the set lower limit value, it is also possible to determine the dressing end time, that is, the dressing tt-. i.e.%
Dressing cycles can also be adjusted with one measuring device. Therefore, the work efficiency can be improved with a simple configuration, and the grinding work can be automated.

Furthermore, since the force acting between the workpiece and the grinding wheel is controlled so as to be kept within a constant range at all times, the accuracy and quality of the ground surface can be improved. Furthermore, since the dressing of the grinding wheel can be controlled to the minimum necessary level to maintain the sharpness of the grinding wheel, it is possible to reduce the wear and tear of the grinding wheel and dresser due to dressing, which is an economical method. See the effect.

[Brief explanation of drawings]

FIG. 1 is a front view of a surface grinder to which a grinding wheel dressing control device according to the present invention is applied. FIGS. 2 to 11 are explanatory diagrams for explaining first to third embodiments of the present invention. 7... Grinding wheel, 10... Grinding resistance detection element, 11
...Workpiece, 14...Dressing device, 0.
...Setting device, ...Arithmetic circuit. Figure 2 (a) External construction object 11 stone stone 7
rr) Graduation 5 Figure ◆ U reach 1 no (entering M between (tilt ``i ze゛ thunder'') $ 4 Figure cap: `` `` 1 `` 1; ro) (a) Plunge RA' 1 , ul!? I width 1 Tadasu (b) Toupa 2kl per person Stone bone bell 1 width Shisho! Power → Oshipeko Lri amount? {7; “1゜. 7■↓River

Claims (1)

[Claims] 1. Grinding characterized by measuring the force acting between the workpiece and the grinding wheel during grinding, and performing dressing when the measured value becomes larger than a preset value. Grinding wheel dressing control method. 2. Measure the force acting between the workpiece and the grinding wheel during grinding, start dressing when the measured value becomes larger than the preset value, and start dressing when the measured value becomes smaller than the preset value. A method for controlling dressing of a grinding wheel, characterized in that dressing is finished when the dressing is finished. 3. A measuring means for measuring the force acting between the workpiece and the grinding wheel, a setting means for setting and storing the upper limit value of the force, and a means for measuring the upper limit value of the force set in the setting means and the measuring means. A dressing control device for a grinding wheel, comprising an arithmetic circuit for comparing measured values, and outputting a signal when the measured value exceeds an upper limit value of force. 4. A measuring means for measuring the force acting between the workpiece and the grinding wheel, a measuring means for setting and storing the upper and lower limits of the force, and the upper and lower limits of the force set in the setting means. It consists of an arithmetic circuit that compares the measured values measured by the measuring means, and is characterized by outputting a signal when the measured value exceeds the upper limit of force or when the measured value becomes smaller than the lower limit of force. Dressing control device for grinding wheels.