JP2717438B2 - Method and apparatus for truing and dressing conductive grindstone by electrolytic dressing grinding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a processing method and a processing apparatus used in grinding in the field of mechanical processing, and in particular, to a conductive material which is being widely applied from high-efficiency processing to precision processing. The present invention relates to a truing and dressing method and apparatus essential for maximizing the performance of a cast iron fiber bond grindstone or the like as a grindstone.

(Prior art) In conjunction with the recent boom of new materials, as the grinding performance of the cast iron fiber bond grindstone, which is a typical example of the rigid metal bond superabrasive grindstone, is generally evaluated, this grindstone aims at high efficiency processing of fine ceramics. Is rapidly spreading. On the other hand, what has become a problem among users of the main grinding wheel is its highly efficient and accurate truing method. In other words, the strong abrasive grain holding power, which is the greatest feature of cast iron fiber bond whetstones, on the contrary, causes difficulty in truing, which is a whetstone shape correction and run-out operation on the processing machine in the early stage of its use. I have.

With respect to a grindstone of a bond material having a self-generating action, there has been a conventional method of easily performing truing by rubbing with another grindstone (trua) having similar properties. In the case of a grindstone having such a self-propelled cutting action, since the abrasive grain holding force is not so strong, it was possible to easily perform truing if the grain size on the truer side was somewhat coarser than that of the truing grindstone. . However, in the case of cast iron fiber bond whetstones, in the same method, the truer side wears out, while the truing side cannot easily remove the runout forever, and the grinding wheel is gradually used as a start-up vehicle. Had to be forced. In such a use, a considerable amount of dummy work is required to get used to the cast iron fiber bond grindstone, and it cannot be said that it is an appropriate use. In fact, for coarse-grained cast iron fiber bond whetstones with a focus on high removal efficiency, the abrasive grain size, that is, the amount of abrasive grain protrusion is large, so even if the truing accuracy is somewhat poor, it is possible to use it while reducing the performance. It can be said that it was done.

On the other hand, the effectiveness of electrolytic in-process dressing grinding, which dissolves and dissociates the grinding wheel bond or grinding debris by weak electrolysis even during processing, has been discovered as a grinding method that maximizes the performance of cast iron fiber bond grinding wheels. Thus, it can be said that the application of a cast iron fiber bond grindstone using fine abrasive grains has entered a practical stage. At present, the application of this electrolytic in-process dressing grinding method realizes not only mirror polishing beyond polishing using fine-grain cast iron fiber bond grinding wheels, but also stable high removal efficiency using coarse-grain cast iron fiber bond grinding wheels. Grinding is also possible. In addition, the application fields of these grinding technologies have continued to expand, and most of hard and brittle materials and metallic materials can be processed with high efficiency and high precision. However, when the fine abrasive grains are applied in the mirror polishing, the truing sweetness which can be ignored in the coarse grain cast iron fiber bond grinding wheel also becomes a serious problem. After all, even if a wheel with a particle size of 100 μm can tolerate a run-out of 10 μm, the initial surface of a 4 μm particle-size grindstone can be 10 μm.
Even if it is shaken by μm, the effective abrasive grains are small even after the electrolytic dressing, and it cannot substantially contribute to the processing.

It has been recognized that the mechanical truing method using conventional truers is extremely inefficient for rigid metal bond wheels such as cast iron fiber bond wheels, and a method using electric discharge machining as a non-mechanical truing method has also been proposed. It has been. However, it was possible to “change the shape” of the metal bond whetstone, but it was not easy to achieve “accuracy” by the method using electric discharge machining. That is, as long as we try to realize truing by the discharge phenomenon, there is a limit even if we try to make the discharge traces small, and if we try to increase the electric discharge machining accuracy, the machining efficiency will be greatly reduced. This is because the inconsistency of being lost could not be resolved. At present, it takes a long time for the initial discharge truing, and it is necessary to stop the machine at every fixed grinding distance and to perform the discharge truing again in order to reduce clogging and blindness after grinding. Although effective EDM was effective as a "forming" technique, it was not appropriate as a "shaping" technique.

Further, in the truing method by electric discharge machining, the diamond abrasive grains on the grindstone surface have to be used while being damaged by electric discharge, and the grinding performance has been reduced with the decrease in the number of effective abrasive grains. Therefore, it is necessary to spend a wasteful cost on improving the mechanical rigidity due to an increase in the grinding resistance, and the grinding stone has been reduced more than necessary by the discharge truing. In general, discharge phenomena are caused by environmental conditions (such as conductivity of machining fluid,
It was pointed out that there was difficulty in setting and maintaining the discharge conditions and electrode conditions, etc.), and that the truing of the CBN grindstone did not remain in the electric discharge machining due to a large difference in the dielectric constant from that of diamond abrasive grains. Furthermore, the fine abrasive grains of the cast iron fiber bond grindstone were harmful and inconvenient. In particular, if discharge truing is used for the fine-grain cast iron fiber bond grindstone, discharge marks remain on the grindstone surface even after electrolytic dressing, and the abrasive grains of the original grindstone cannot be used effectively. In this case, the removal of the wobble of the grindstone surface causes concavities and convexities to be formed on the grindstone surface, and the performance of the electrolytic in-process dressing mirror surface grinding is reduced.

The conventional mechanical truing method and the truing method by electric discharge machining cannot be said to be appropriate truing methods for rigid metal bond super-abrasive wheels such as cast iron fiber bond wheels due to the above-mentioned disadvantages. If anything, on the spot, the former has often been unavoidably used as a truing method for fine-grain cast iron fiber-bonded whetstones and the latter for coarse-grained cast-iron fiber-bonded whetstones. As an adverse effect, the quality of truing has a long-lasting effect on the grinding performance, and consequently, the skill difference between operators has become remarkable.

(Problems to be Solved by the Invention) In the present invention, the conventional mechanical truing and dressing method or the truing and dressing method by electric discharge machining could not be said to be a method suitable for a rigid metal bond superabrasive grindstone, That is, (1) truing efficiency,
The main objective is to solve the main factors such as (2) truing accuracy, (3) truing and dressing quality, and (4) truing and dressing consistency.

First, the problems (1) and (2) are problems in which the truing efficiency and accuracy of cast iron fiber bond wheels and the like have not been able to be easily realized as in the case of general whetstones. This is a problem in that truing and dressing cannot be performed without smoothing the abrasive grains as much as possible and without damaging the abrasive grains. Further, the problem (4) is that the truing and the dressing have been inconsistent so far, and have been performed independently by a method without any context (abrasive particle diameter used, grinding method, etc.) on a case-by-case basis. If all the basic problems of (1), (2) and (3) can be solved and systematized easily,
The problem of (4) will also be solved. Only by solving these problems will an unprecedented powerful truing and dressing system be constructed.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the inventors focused on (1) a mechanical truing method using a truer with less wear, and (2) sharpness of the truer. (3) Adopted electrolytic dressing for sharpening of truing grindstone, (4) Systematized mechanical truing and electrolytic dressing, etc. (1) and (2) In order to solve the above problem, it has been found that it is necessary to change the truer itself from a conventional grindstone to a high-strength grindstone and to apply electrolytic dressing as a conductive grindstone.

Furthermore, in order to utilize the above (3) and (4), a solution by a system in which, after truing while applying an electrolytic dressing to a high-strength conductive grindstone, the electrolytic dressing is immediately switched to a truing grindstone. I came to think. In other words, in the present invention, in order to effectively realize the electrolytic dressing grinding method which is considered to be a method of maximizing the performance of the rigid metal bond superabrasive grindstone, a similar grindstone is used as a truer by electrolytic dressing grinding. As a result, highly efficient and precise truing can be realized. The new truing and dressing method uses a cast iron fiber bond (diamond / CBN Irrespective of coarse particles / fine particles).

After all, the truing and dressing method according to the present invention is the most serious and most rational in that, in order to perform high-efficiency and high-precision grinding with a grindstone, the grinding wheel must start with high-efficiency and high-precision machining. It is nothing less than a way to realize basic facts faithfully and reliably.

(Operation) When the same kind of grindstones, especially metal bond grindstones, are rubbed with each other by the normal grinding method, naturally, they are not easily worn away and the bonds tend to weld together. Truing cannot be easily realized. Also, depending on the relationship of the abrasive grain size used, there is a danger that the wear of the grindstone which becomes a lure becomes extremely large even if welding does not occur. When electrolytic dressing is not added to the truer, the truer with a small diameter generally loses to the truing grindstone due to the difference in peripheral speed, and the amount of wear of the truer and the truing grindstone is determined at a value almost close to the reciprocal of these diameter ratios. Can be expected to come. In other words, when electrolysis is not applied, even if these grindstones have the same particle size, the truer is overwhelmingly lost, and in reality, the wear amount will be several times that of the truing grindstone. In this case, highly efficient and precise truing cannot be realized, but if truing is provided to the truing while electrolytically dressing a metal bond whetstone as a truer,
The opposing whetstone is ground by a constantly sharpened whetstone, and it is expected that the adverse effects expected in the normal grinding can be solved at once. This is a powerful truing action in the present invention.

FIG. 1A is a diagram illustrating this truing step of the present invention. A brake truer 8 having a conductive grindstone portion 6 is mounted on a brake truer 4 installed on the machine tool table 2. A truing grindstone 12 having a conductive grindstone portion 10 rubbed against the conductive grindstone portion 6 of the truer 8 is mounted on a rotary drive shaft 14. The grinding fluid is supplied from the nozzles 16 and 18, but comes in contact with the grinding fluid supplied from the nozzle 16,
An electrode 20 is provided facing the conductive grindstone portion 6. A power supply brush 22 is provided in electrical contact with the conductive grindstone portion 6. The electrode 20 and the power supply brush 22 are connected to a power supply 24 as a cathode and an anode, respectively. When the drive shaft 14 is rotated while the electrolytic grindstone portion 6 of the truer 8 is electrolytically dressed based on such a configuration, the conductive grindstone portion 6 of the truing grindstone 12 is trued very well. In the above description, the truing grindstone 12 was driven and the truer 8 was rotated in the following manner.
It is obvious that the truer 8 may be driven to rotate the truing stone 12 in the reverse direction. Further, in the case of a lap grinder described later with reference to FIG. 3C, both the truing grindstone 12 and the truer 8 are driven to perform truing.

If this truing method is applied to a cast iron fiber bond diamond grindstone, etc., the target truing grindstone surface can be smoothed by diamond dressing which is always sharpened by electrolytic dressing action and firmly held by the cast iron fiber bond. Therefore, not only high efficiency but also high precision truing can be easily realized. In particular, if this method is applied to the truing of a fine-grained cast iron fiber bond grindstone, it is thought that it is easy to ensure that the wobble of the grindstone surface is within the abrasive grain size by the same action, Almost all of the protruding abrasive grains can contribute to mirror polishing, and it can be sufficiently expected that the finally obtained mirror polishing finish accuracy slightly exceeds the conventional truing method. Even if the truer wheel and the truing wheel have the same grain size and the former is a fraction of the diameter of the latter, it is highly expected that the position of the truing will be completely reversed from that of the normal truing, and that the truer will surpass the truing wheel. it can. At the same time, if the electrolytic dressing is appropriately applied to the truers, it is considered that the amount of wear of the truers can be extremely small. It is considered that such true truing action further reduces the amount of truing wear when the truing target grindstone has a finer grain size than the truer or in the case of CBN abrasive grains. Even with the same grain size, it is considered that the amount of wear of the truer stone that is electrolytically dressed is small because of the large number of effective abrasive grains and the smooth removal of grinding debris, the diffusion rate of friction heat etc. is large and the thermal damage of diamond abrasive grains is large. Can be mentioned.

On the other hand, in order to effectively utilize the cast iron fiber bond grindstone trued with high efficiency and high accuracy by the above-described operation in the grinding process, electrolytic dressing is performed not on the truer but on the trued grindstone side. That is, during dressing, electrolytic dressing is performed on the truer, which is a cast iron fiber bond diamond grindstone, and on dressing, on the cast iron fiber bond grindstone used for grinding.

FIG. 1B is a view for explaining the electrolytic dressing step of the truing grindstone of the present invention. Grinding fluid is supplied from a nozzle 26 to the conductive grindstone portion 10 of the truing grindstone 12, and an electrode 28 is provided in contact with the grinding fluid supplied from the nozzle 26 and opposed to the conductive grindstone portion 10. ing. Also,
A power supply brush 30 is provided in electrical contact with the conductive grindstone 10. The electrode 28 and the power supply brush 30 are connected to the power supply 24 as a cathode and an anode, respectively. Thereby, the electrolytic dressing of the conductive grindstone portion of the truing grindstone after truing is performed. According to the present invention,
Extremely efficient truing and dressing action can be realized. It is possible to carry out the two processes shown in FIGS. 1A and 1B consistently (with the same equipment),
It is also highly preferred to do so.

Further, the present electrolytic dressing step may be performed in parallel with the grinding of the workpiece by the truing grindstone.

According to the present invention, an extremely efficient truing and dressing operation can be realized.

(Example) Specific configuration example of the present invention Hereinafter, the present invention will be described in detail based on preferred embodiments.

FIG. 2 is a schematic view of an apparatus for carrying out the truing and dressing method of the present invention, and FIG. 1A and FIG.
FIG. 1B is a schematic view of an apparatus that switches between the two processes shown in FIG. 1B. 1A and 1B are denoted by the same reference numerals for the same components as those shown in FIGS. 1A and 1B, and description thereof will be omitted.In the present configuration, the electrodes 20, 28 and the power supply brush 22, 30 is characterized in that a voltage is applied from the same power supply 24 via the switches SW1 and SW2. In this device, first, switches SW1 and S
The W2 is switched to the A side, and the truing-target grindstone 12 is subjected to electrolytic in-process dressing grinding with the coarse-grained cast iron fiber-bonded diamond grindstone 8 as a truer to finish the cast iron fiber-bonded diamond grindstone 12 used for grinding (truing mode). The switches SW1 and SW2 are automatically switched to the B side (by a time sequence), and the electrolytic dressing is automatically performed on the cast iron fiber bond grindstone 12 which has been precisely trued and finished (dressing mode).

The truing dressing system shown in FIG. 2 is integrated with a grinding device for a workpiece, and after the truing grindstone performs electrolytic dressing grinding on the workpiece for a predetermined period (or the truing grindstone loses its shape). If the truing and the process are carried out automatically each time (a time is observed by the sensor), complete automation of the grinding operation will be achieved. As a specific configuration, an object to be processed may be installed on an extension of the rotation center of the truer so that the truing grindstone 12 can be moved in and out between the truer 8 and the object to be processed.

In both the truing mode and the dressing mode, there is provided an electrolytic dressing apparatus which generates a weak electrolysis by using a cast iron fiber bond grinding wheel side as a (+) pole and an attachment facing each grinding wheel surface as a (-) pole. Since this device can also be used as a single device, this system has an effect of enhancing functionality. Stable precision truing is realized by electrolytic dressing grinding of powerful truers, and sharpening can be automatically realized at high speed by circuit switching.Thus, truing and dressing action according to the present invention is achieved by rigid metal bond grinding wheels such as cast iron fiber bond grinding wheels. It will make a great contribution to the automation of the machining process using.

In addition, among the truing and dressing methods of the present invention, regarding truing, high efficiency of non-conductive grindstone,
It can be expected that it is extremely effective as a high-precision truing method. In recent years, not only a rigid bond wheel other than a metal bond wheel, but also a so-called elastic bond wheel, a composite bond wheel having various composite forms has appeared.
Some of these are also difficult to apply the conventional truing method. In an apparatus for practicing the present invention as shown in FIG. 2, by replacing such a non-conductive bond wheel with a conductive bond wheel, , Suitable truing can be achieved. At this time, electrolytic dressing of the non-conductive bond grindstone is not performed.

According to the above-described method and operation, it is expected that a great benefit can be obtained by systematizing the new truing / dressing method according to the present invention in correspondence with various processing methods. Including the method shown in Fig. 2 in which a straight grindstone is operated on a machining center, the 3A is suitable for various processing methods and tools such as a surface grinder, cylindrical grinder, and lap grinder.
Systems classified as shown in FIG. 3, FIG. 3B, and FIG. 3C can be configured. FIG. 3A shows a type applied to surface grinding and the like. In this case, the material to be ground is set on the side of the truer 8, the truing stone can be moved between the truer 8 and the material to be ground, and the truing stone is trued as required. . FIG. 3B shows a type applied to cylindrical grinding and the like. Also in this case, truua 8
The workpiece to be ground is placed on an extension of the rotation axis of the workpiece, and the truing grindstone can be moved between the truer 8 and the workpiece, and truing is performed as necessary. FIG. 3C shows a type applied to lap grinding and the like. in this case,
When the material to be ground is removed, the truer 8 moves onto the truing grindstone 12 to truing the truing grindstone 12. 3A, 3B and 3C, a voltage is applied between the electrodes A (+) and A (-) during tooling, and the electrodes B (+) and B during electrode dressing of the truing-target grindstone. A voltage is applied between (−).

If applied in any of the types of truing devices shown in FIG. 2, FIG. 3A, FIG. 3B and FIG. 3C, or a combination of these, existing processing machines (general-purpose NC processing machines, dedicated grinding machines, etc.) .) Above can be used to the fullest extent.

Next, the results of a comparative experiment performed to confirm the difference in the effect of the truing process of the present application performed while applying electrolytic dressing to the truer will be described below.

The experiment was performed using the apparatus shown in FIG. Specific experimental conditions are shown in Table 1 below.

Truer and truing whetstone have a grain size of # 140, concentration 100
Is the same except for the diameter.

 The experimental results are shown in Table 2 below.

As shown in Table 2A, in the case of a normal truing in which no electrolytic dressing is applied to the truer, even if the cutting is performed by about 100 μm, only the two grinding wheels are reduced, and the run-out of the truing grindstone is 10%.
μm was not cut. As a result, the truer and the truing grindstone having the same grain size and the larger peripheral speed are stronger and the wear ratio is almost opposite to the diameter ratio. It was reconfirmed that if the truer wear was large, high-speed and precise truing could not be expected.

When the truing was performed while applying the electrolytic dressing to the truer, the positions of the respective grindstones were reversed from those of the previous normal truing, and the truer in which the effective abrasive grains increased in the electrolytic dressing began to grind the truing grindstone. in this case,
Even though the diameter was small, the truing grindstone hardly abraded, and as shown in Table 2B, the wear amount of the truing grindstone was close to the run-out reduction amount, and there was almost no waste. As a result, it was confirmed that the truing method of the present invention, in which truing is performed while applying electrolytic dressing to truers, can be trued even with the same particle size, and the wobble of the grindstone can be reduced to 1/5 or less in a much shorter time than usual.

In addition, when truing was performed while applying electrolytic dressing to the truer, it was confirmed that the surface of the truing-target grindstone was extremely glossy as compared with a surface formed by ordinary truing and had a smoothness close to a mirror surface. Unless in this state, sufficient grinding ability cannot be exhibited.

Application to mirror-surface grinding Mirror-surface grinding, which is expected to have a remarkable electrolytic dressing truing effect, was performed. Using a # 8000 cast iron fiber bond diamond grindstone which has been subjected to conventional truing (using # 100 and # 400C grinding stones) and electrolytic dressing truing (using # 140 cast iron fiber bond diamond grinding stone), the silicon wafer is processed by the apparatus shown in Fig. 3C. Mirror grinding was performed.

It is more difficult to obtain smoothness with conventional truing than with fine-grained grinding stones, and even if electrolytic dressing is used, effective abrasive grains are not enough to obtain a sufficiently smooth surface.However, grinding stones with electrolytic dressing truing have # 8000 abrasive grains. It was found that the difference between them reached about three to four times the roughness.

(Effect of the Invention) According to the present invention, it can be said that a truing and dressing method most suitable for a rigid metal bond super-abrasive wheel represented by a cast iron fiber bond wheel is systematized. The new truing and dressing system according to the invention will be realized very efficiently, from high efficiency grinding to precision finishing grinding. Since the present invention makes it possible to use the grindstone in a manner independent of the grain size of the grindstone, it is considered that the skill difference in using the metal bond grindstone, which has been particularly problematic until now, is greatly reduced by the present system. At the same time, it can be expected that the grinding removal efficiency and the grinding accuracy that could not be easily realized by the conventional use methods can be easily realized.

Further, the present invention is considered to greatly contribute to automation and unmanned grinding processes. It is said that the conventional grinding process could not be easily automated because of a problem in using a grinding wheel. The fact that the present invention solves truing and dressing, which is a major factor in the problem of using a grindstone, will definitely promote automation of grinding in a production process. In addition, due to the effect of the present invention, a mirror finish that relied on polishing such as a plurality of lappings in an existing production process is likely to be replaced one after another by a mirror grinding process using the present system. .

Looking at the truing technology of metal-bonded super-abrasive grindstones so far, there is a feeling that we have concentrated our efforts only on the formation of tough grindstones. However, the truing according to the invention
Dressing technology can be called true truing dressing, and it is a person who performs dressing while minimizing the amount of grindstone to be removed before use and performing dressing with minimal damage to abrasive grains Truing and dressing efficiency that cannot be achieved by techniques can be easily realized. This can be said to be a system in which the rigid metal bond superabrasive grindstone, which originally has little wear, is used up without being further reduced to the limit. By linking the truing condition and the dressing condition, it can be used with little reduction from the time of purchase and installation of the grindstone, which will maximize the cost performance of the grindstone.

Further, since the wear of the cast iron fiber bond diamond grindstone is extremely small as compared with the conventional truer grindstone, it is considered that the necessity of replacing the truer grindstone is also a great effect according to the present invention. Since the in-process dressing method can realize grinding while automatically controlling the sharpness of cast iron fiber bond wheels, high efficiency and high precision truing, which will greatly contribute to fully automated (unmanned) grinding work in the future. It is expected to be a dressing grinding system.

[Brief description of the drawings]

FIG. 1A is a schematic diagram illustrating a truing step of the present invention, FIG. 1B is a schematic view illustrating an electrolytic dressing step on a truing grindstone of the present invention, and FIG. 2 implements the truing and dressing method of the present invention. FIG. 3A, FIG. 3B, and FIG. 3C are schematic diagrams when applied to various types of grinding machines of the present invention. 2 ... machine tool table 4 ... brake truer 6 ... conductive grindstone 8 ... truer 10 ... conductive grindstone 12 ... trued whetstone 14 ... rotary drive shaft 16, 18, 26 ... nozzle 20 , 28 ... Electrode 22,30 ... Power supply brush 24 ... Power supply

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-283861 (JP, A) JP-A-54-111193 (JP, A) JP-A-51-38192 (JP, A) 97566 (JP, U) Jiko 45-12559 (JP, Y1)

Claims (6)

(57) [Claims] 1. An electro-dressing process is applied to a conductive grindstone portion of a truer to maintain the protrusion of abrasive grains on a grindstone surface. In parallel with the electrolytic dressing, a truer is applied to a conductive grindstone portion of a trued grindstone by the truer. A method of truing and dressing a conductive grindstone by electrolytic dressing grinding in which electrolytic dressing grinding is performed on the conductive grindstone portion of the truing-target grindstone on which the truing is performed. 2. The method according to claim 1, wherein said conductive grindstone portion is made of abrasive grains and a metal bond. 3. The method according to claim 1, wherein said conductive grindstone comprises a grindstone and a non-metal bond containing metal particles. 4. A first support means for supporting a truer having a conductive grindstone portion, a second supporting means for supporting a trued grindstone having a conductive grindstone portion to which a truer is applied by the truer, Driving means for driving at least one of the truing grindstones, rotating the other, and causing frictional sliding between the grindstone portion of the truer and the grindstone portion of the truing grindstone, wherein the truer grindstone portion is the anode side. A grinding fluid in contact with the grinding wheel portion of the truer as a cathode side, first voltage applying means for applying a voltage between them, and a grinding wheel portion of the truing grindstone as an anode side, and a grindstone of the truing grindstone. A conductive grinding wheel formed by electrolytic dressing grinding comprising a second voltage applying means for applying a voltage between the grinding fluid and the grinding fluid in contact with the portion as a cathode side -Dressing and dressing equipment. 5. The apparatus according to claim 4, wherein a voltage is applied to said first voltage applying means and said second voltage applying means from the same power supply. 6. A switch is provided between the first voltage applying means and the second voltage applying means and the power supply, and the changeover switch allows the first voltage applying means to be connected to the first voltage applying means. When the power supply is connected, the grindstone portion of the truer is electrolytically dressed. When the power supply is connected to the second voltage applying means, the changeover switch causes the grindstone portion of the trued grindstone to be electrolytically dressed. Apparatus according to claim 5, characterized in that it is dressed.