JP2660512B2 - On-machine discharge truing method of metal bond whetstone - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of truing a grindstone, particularly to an on-machine discharge truing method of a metal bond grindstone. [Prior art and its problems] Truing on a machine such as a grinder, a jig grinder, or a grinder center is indispensable for performing highly accurate and efficient grinding of hard and brittle materials. However, there was no effective method for a metal bond whetstone among whetstones. As a countermeasure, the present inventors have developed a method of performing on-machine discharge truing of a metal bond grindstone using a wire electrode 100 as shown in FIGS. 10 and 11. According to this method, there is an advantage that high precision for truing on the machine can be achieved. However, since the discharge location is local due to the wire electrode, and the average current value is limited, the removal efficiency is insufficient, the truing efficiency is reduced, and the wire thickness is limited. There is a problem in that the shape of the formed truing is restricted, and for example, sharp irregularities and complicated shapes cannot be created. As a countermeasure for this, the use of a block-shaped electrode is conceivable, but there is a problem that the truing accuracy is reduced because an electrode mounting error and electrode wear are inevitable. [Means for Solving the Problems] The present invention has been made by research to solve the above-mentioned problems, and its object is to provide a complicated,
Another object of the present invention is to provide a method capable of accurately, efficiently, and easily performing on-machine truing of a metal bond grindstone having a sharp shape. In order to achieve this object, the present invention utilizes a drive system of a device capable of performing various processes such as various grinding machines and machining centers capable of grinding, and creates and discharges an electrode for discharge truing on the machine. On-machine discharge truing is performed using the generating electrode as it is. That is, the present invention is a method of discharging truing a metal bond whetstone on a machine, in which an electrode of a desired shape is created from an electrode material by a cutting tool attached to a main shaft of the apparatus,
It is a basic feature that the discharge truing of the target grindstone replaced with the main shaft is directly performed using the creation electrode as it is. In addition, the discharge truing of the target grindstone using the generating electrode includes performing the roughing / medium processing by increasing the discharge current value, and then performing the finishing processing by weakening the discharge current value. Although the present invention is effective for on-machine discharge truing with a form electrode, it can also be applied to on-machine discharge truing for plane cutting with a straight electrode. Further, the present invention is also effective as an on-machine discharge dressing method. In the present invention, the cutting tool includes not only a cutting tool and an end mill but also a metal-bonded grindstone which is given a shape outside the machine in advance. Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 to 5 show an on-machine discharge truing method of a metal-bonded grindstone using a form electrode on a vertical machining center (in this case, used as an NC grinding machine). 1 to 3 show the first stage, that is, an on-machine electrode forming process. Numeral 1 denotes an NC table of a machining center provided with a numerical controller and an automatic tool changer (ATC). The mechanism allows horizontal movement. Reference numeral 2 denotes a rotating shaft (truer shaft) removably mounted on the NC table 1 and is rotatable by a motor 3. Reference numeral 4 denotes a spindle of the machining center, which is provided on a spindle head 4a via a bearing, and is rotatable and vertically movable. In the first stage, first, a cylindrical electrode material 6 made of a conductive material such as graphite or copper is fitted to the rotating shaft 2 and fixed by a member 20 such as a nut. At this time, a brush 8 is attached to the electrode material 6. On the other hand, a cutting tool such as a cutting tool 7 in this example is provided directly on the spindle 4 or on a tapered portion of an axis extending from the spindle 4 (hereinafter referred to as the spindle).
Is mounted with the holder 5 (taper shank portion). This tool is automatically selected and installed by ATC. In this state, the rotary shaft 2 is rotated by the motor 3 and the NC table 1 and the main shaft 4 are operated in accordance with the functions. On the machining center machine, a cutting electrode 7a having a desired shape is formed from the cutting tool 7 and the electrode material 6. Is created. FIGS. 4 and 5 show the second stage, the discharge truing step with the generating electrode. In the second stage, first, the metal-bonded grindstone 9 is selected by ATC with the formed electrode 6a directly attached to the rotating shaft 2, the cutting tool 7 is removed from the main shaft 4, and the metal-bonded grindstone 9 is replaced with the metal-bonded grindstone 9. I do. That is, the shank portion 50 of the holder 5 is fitted to the tapered portion 40 of the main shaft 4 as shown in FIG. And then
The main shaft 4 and the rotating shaft 2 are rotated while a predetermined gap is provided between the metal bond grinding wheel 9 and the forming electrode 6a by the NC table 1, and at the same time, a discharging current is supplied from the power source 10 to the brush 8 and the shaft 50. Further, a machining fluid is supplied from the machining fluid nozzle 11 to the discharge gap. As a result, the metal bond grindstone 9 is subjected to discharge truing by the rotating shaped electrode 6a. In the discharge truing step using the block-shaped electrodes, the removal rate is most strongly affected by the current value. Sixth
The figure shows a cast iron bond diamond wheel (diameter 30 mm, abrasive grain size # 600, degree of concentration 1) using a 38 mm block electrode made of copper.
00) is a result of examining the relationship between the removal amount Td of the grindstone and the removal time t per unit width of the grindstone when the truing is performed on the machine, with the setback amount being constant (20 μm, the driving depth 0 mm). The peripheral speed of the grindstone was 25 m / min, the no-load voltage was 100 V, the discharge time, and the pause time were 1 μs. As is clear from FIG. 6, the removal rate is η = Td / t
(Time / width), the removal efficiency is 6μ at a set current of 40A.
55 mm / mm / min, set current 80A (maximum discharge gap 130μm)
μm · mm / min, and the higher the current value, the higher the removal efficiency. Therefore, in actual on-machine discharge truing, first, the discharge current value is increased, and rough / medium processing is performed by the creation electrode 6a. After that, the discharge current value is weakened, and the finish discharge truing is performed. In this process, when the generating electrode 6a is worn out by rough / medium processing, the metal bond grindstone 9 is removed from the main shaft 4 via the holder 5, and is replaced with a cutting tool for correction by ATC. The cutting electrode may be modified on-machine by cutting with the technique shown in FIG. 3, the cutting tool may be replaced with a metal bond grindstone 9 again, and the discharge current value may be weakened to perform finish discharge truing. FIGS. 7 (a) and 7 (b) show a forming whetstone obtained by performing forming truing according to the present invention and a generating electrode used for forming truing. You can see that it can be created. FIG. 8 and FIG. 9 show the on-machine electrode creation for the non-form grindstone and the discharge truing situation by the creation electrode according to the present invention. In this case, as a first step, a fixing member 12 is attached to an NC table (not shown), and an electrode material 6 'is attached thereto.
Is fixed. On the other hand, a rotary tool 7 ′ such as an end mill is attached to the main shaft or the shaft by the holder 5, and the electrode material 6 ′ is cut on the machine by this, and the electrode 6 a ′ for truing is cut.
Get. Then, a metal bond grindstone 9 'is mounted on the main shaft or the shaft instead of the tool 7', and a discharge current is supplied from the electrode 10 to the mounting shaft of the metal bond grindstone 9 'and the generating electrode 6a'. The discharge truing is performed by bringing the generating electrode 6a 'close by the NC table while rotating the bond grindstone 9', and also in this case, the discharge current value is weakened stepwise, and the tool exchange is performed in the same manner as the above method. To correct the electrode. At the time of discharge truing of the non-form grinding wheel, a method of reciprocating the generating electrode in parallel with the generating surface may be adopted. According to the present invention, it is also possible to remove the runout of the grindstone or to perform the discharge dressing by reducing the processing conditions by using a metal bond grindstone (a grindstone having an irregular shape) formed in advance outside the machine. It is. That is, specifically, a metal bond whetstone that has been given a shape in advance outside the machine is attached to the main shaft,
By rotating the electrode, an electrode can be created, the electrode can be used to deflect the grindstone, and the discharge conditions can be reduced by reducing the processing conditions. The present invention is not only for machining centers, but also for NC grinders,
It is applied to on-machine truing such as jig grinders, grinding centers, NC cylindrical grinders, and tool-changeable lathes. [Effect of the Invention] According to the present invention described above, since the block-shaped electrode is created on the machine utilizing the function of the cutting machine, it is not necessary to prepare a shaped electrode in advance, and the creation is performed as it is. Performing on-machine truing with electrodes does not involve electrode mounting errors, and can be corrected freely by replacing the grindstone and cutting tool on the main spindle. In addition, an excellent effect that an efficient and accurate on-machine discharge truing can be realized by taking advantage of the block electrode can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing the principle of the first stage of the on-machine discharge truing method of a metal bond grinding wheel according to the present invention, FIG. 2 is a detailed view thereof, and FIG. Partially enlarged view of the figure,
FIG. 4 is a side view showing the principal part of the second stage of the present invention,
FIG. 5 is a detailed view thereof, FIG. 6 is a graph showing the relationship between the discharge time per unit width of the grinding wheel by the block-shaped electrode, the removal amount of the grinding wheel and the current value, and FIGS. 7 (a) and 7 (b) are formed by the present invention. FIG. 8 is a perspective view showing a metal bond grindstone formed and a generating electrode used for molding, FIG. 8 is a perspective view showing an on-machine electrode forming state when a non-formal grindstone is targeted, and FIG. Perspective view showing discharge truing situation by electrode, 10th
FIG. 11 is a side view showing a conventional on-machine truing method, and FIG. 11 is a perspective view of the principal part thereof. 1 NC table, 4 spindle, 6 electrode material, 6a, 6
a ': Creation electrode, 7, 7': Cutting tool for creating electrode shape, 9, 9 ': Metal bond whetstone

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Takeo Nakagawa               223-4, Nobutsubo, Nakahara-ku, Kawasaki-shi (72) Inventor Tatsuhito Yanase               14-1 Nakataikoyama, Kosugi-cho, Imizu-gun, Toyama Prefecture                (56) References JP-B 61-61927 (JP, B2)                 Tokiko Sho 61-159333 (JP, B2)                 Jikken 45-12559 (JP, Y1)

Claims (1)

(57) [Claims] In a method of discharging a metal bond whetstone on a machine, discharge truing of a target whetstone replaced with a main spindle is performed by using a cutting tool attached to a main spindle to create an electrode having a desired shape and using the generated electrode as it is. On-machine discharge truing method of metal bond whetstone. 2. The on-machine electric discharge truing method of a metal bond grinding wheel according to claim 1, wherein a block-like shaped electrode is created by using a cutting tool as a cutting tool. 3. The on-machine electric discharge truing method of a metal bond grindstone according to claim 1, wherein a straight or free-form surface is formed on the electrode surface using a rotary tool such as an end mill as a cutting tool. 4. 2. The method according to claim 1, wherein the discharge truing of the target grindstone using the generating electrode includes, after performing rough and medium machining with a high discharge current value, performing finishing with a weak discharge current value. An on-machine electric discharge truing method of the metal bond grindstone described in the above.