JP3988630B2 - Coolant supply method and apparatus for grinding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coolant supply method and apparatus in a grinding machine.
[0002]
[Prior art]
Conventionally, when grinding a workpiece with a grinding wheel, coolant is supplied to the grinding point between the workpiece and the grinding wheel to cool and lubricate, thereby preventing grinding burn, thermal distortion, etc. of the workpiece due to grinding heat. . Grinding of a workpiece is performed by grinding a grinding wheel with a rough grinding feed and a finish grinding feed with different feed speeds, and temporarily stops at a forward end and performs a spark-out grinding. In rough grinding feed, the amount of heat generated is high and the temperature is high, so it is necessary to supply a large amount of coolant. In finish grinding feed, the amount of heat generated is small, so a small amount of coolant may be supplied. However, if excessive coolant is supplied toward the grinding point between the workpiece and the grinding wheel during finish grinding feed, the dynamic pressure generated by the coolant between the workpiece and the grinding wheel increases, and When there is a hole or groove, the dynamic pressure changes due to the hole or groove, causing relative displacement between the workpiece and the grinding wheel, resulting in a problem that the finishing accuracy of the workpiece is lowered. A technique for preventing a decrease in grinding accuracy due to the dynamic pressure effect is disclosed in Japanese Utility Model Publication No. 61-19910. In this prior art, when the grinding feed rate is switched from the rough grinding feed rate to the finish grinding feed rate, the coolant flow rate is reduced to prevent a reduction in grinding accuracy due to the dynamic pressure effect.
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 61-19910 (page 2, Fig. 2)
[0004]
[Problems to be solved by the invention]
In the prior art, in order to reduce the coolant flow rate at the time of switching the grinding feed speed, equipment such as a separate system of coolant piping is necessary, and if the flow rate is switched within a short processing time, the flow rate is stabilized. There was a problem that accuracy deteriorated.
[0005]
In addition, recently, an air jet is blown across the grinding wheel surface from the one side to the other side at the upstream position in the grinding wheel rotation direction from the grinding point, and the air jet moves around the grinding wheel. By cutting off the air layer associated with the grindstone, a coolant supply device has been put into practical use that allows even a small amount of coolant to adhere well to the grinding surface of the grindstone and sufficiently supply the grinding point. In some cases, the coolant flow rate was switched to prevent a decrease in grinding accuracy due to the dynamic pressure effect.
[0006]
The invention has been made to solve the conventional problems, and the dynamic pressure at the grinding point is reduced by stopping or reducing the flow rate of the fluid jet that jets across the grinding surface in order to block the air layer associated with the grindstone. The reduction is to improve the grinding accuracy.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the structural feature of the invention described in claim 1 is that a grinding wheel supported by a grinding wheel base and driven to rotate is supported by a workpiece support device and rotated. In a coolant supply method in a grinding machine that grinds the workpiece with the grinding surface of the grinding wheel while supplying the coolant relatively to the grinding point and supplying the coolant to the grinding point, the upstream position in the grinding wheel rotation direction from the grinding point A fluid jet nozzle is provided for spraying the fluid jet so as to cross from the one side to the other side along the grinding surface of the grindstone in order to block the air layer accompanying the grindstone that rotates around the grindstone. When decreasing the amount of coolant supplied to the grinding point, the fluid jet is stopped or the flow rate is reduced.
[0008]
The structural feature of the invention according to claim 2 is that, in the first aspect, when the workpiece is roughly ground by the grinding surface of the grinding wheel, an air layer associated with the grinding stone is blocked by the fluid jet, When coolant is supplied to the grinding point without being hindered by the air layer associated with the grindstone, and finish grinding is performed, the fluid jet is stopped or the flow rate is reduced to reduce the amount of coolant supplied to the grinding point. That is.
[0009]
According to a third aspect of the present invention, the grinding wheel supported by the grinding wheel platform and driven to rotate is relatively ground toward the workpiece supported by the workpiece support device and rotated. In a grinding machine that grinds the workpiece by the grinding surface of the grinding wheel while supplying coolant to the grinding point, an air layer associated with the grinding wheel that rotates around the grinding wheel at a position upstream of the grinding point in the grinding wheel rotation direction. In order to cut off, a fluid jet nozzle that sprays the fluid jet along the grinding surface of the grindstone from one side to the other side is provided to reduce the amount of coolant supplied to the grinding point. In order to make the fluid jet, means for stopping the ejection of the fluid jet or reducing the flow rate is provided.
[0010]
[Operation and effect of the invention]
In the invention which concerns on Claim 1 comprised as mentioned above, the grindstone rotatably supported by the grindstone base and the workpiece supported by the workpiece support apparatus are moved relatively, and the workpiece is ground on the grinding wheel. Grinding while supplying coolant to the grinding point. At the upstream side of the grinding wheel rotation direction from the grinding point, the fluid jet is sprayed from the fluid jet nozzle along the grinding surface of the grinding stone so as to cross from the one side to the other side, and accompanied by the grinding wheel. Air layer is blocked. When reducing the coolant supply to the grinding point, stop jetting the fluid jet or reduce the flow rate to increase the amount of the air layer associated with the grinding wheel that reaches the grinding point, deflecting the coolant flow toward the workpiece and grinding. Decrease the proportion of coolant supplied to the point and increase the proportion of coolant applied to the workpiece.
[0011]
This makes it possible to quickly deflect the coolant flow toward the workpiece side with a simple and inexpensive configuration, without providing a drive device for tilting the coolant nozzle, and to reduce the flow rate when necessary. The flow rate to be supplied is reduced, the dynamic pressure generated at the grinding point by the coolant is reduced, and even if there are notches such as oil holes and grooves in the grinding part of the workpiece, the dynamic pressure changes greatly due to the effects of the notches. Thus, it is possible to prevent the roundness from being lowered or chattering. At the same time, the amount of coolant applied to the workpiece can be increased to sufficiently cool the workpiece, and the dimensional accuracy can be improved.
[0012]
In the invention according to claim 2 configured as described above, at the time of rough grinding, the grinding stone associated air layer is blocked by the fluid jet, and the coolant is supplied to the grinding point without being obstructed by the grinding stone associated air layer. During finish grinding, the jet of fluid is stopped or the flow rate is reduced, and the amount of coolant supplied to the grinding point is reduced by the air layer accompanying the grinding wheel. As a result, during rough grinding, the coolant is sufficiently supplied to the grinding point without causing grinding burn and thermal distortion in the work part of the workpiece. Accuracy can be improved.
[0013]
In the invention according to claim 3 configured as described above, the fluid jet ejected from the fluid jet nozzle provided at the upstream position in the grinding wheel rotation direction from the grinding point is transferred from one side surface along the grinding surface of the grinding stone. Jets to cross the side. The fluid jet blocks the air associated with the grindstone that rotates around the grindstone, and the coolant is sufficiently supplied to the grinding point without being obstructed by the air associated with the grindstone. When decreasing the coolant supply to the grinding point, stop the jet of fluid or reduce the flow rate to increase the amount of the air layer associated with the grinding wheel that reaches the grinding point, and deflect the coolant flow toward the workpiece side for grinding. Decrease the proportion of coolant supplied to the point and increase the proportion of coolant applied to the workpiece. This cuts off or reduces the flow rate of the fluid jet to block the air layer associated with the grindstone, thereby quickly deflecting the coolant flow toward the workpiece and reducing the flow rate supplied to the grinding point. It is possible to provide a grinding machine that suppresses the generation of dynamic pressure and improves the grinding accuracy.
[0014]
[Embodiment]
Hereinafter, a coolant supply method and apparatus in a grinding machine according to an embodiment of the present invention will be described with reference to FIGS. A grindstone table 11 is slidably mounted on the bed 10 and moved forward and backward in the X-axis direction approaching and separating from the workpiece W by a servo motor 12 via a ball screw mechanism. A grindstone shaft 13 having a grindstone G attached to one end is rotatably supported on the grindstone base 11 and is rotationally driven by a motor. The grindstone G is configured by adhering a plurality of grindstone chips to the outer peripheral surface of a disk-shaped base formed of a metal such as iron or aluminum. A table 14 is slidably mounted on the bed 10 and is moved by a servo motor 15 via a ball screw mechanism 16 in the Y-axis direction perpendicular to the X-axis. A headstock (not shown) and a tailstock 18 constituting the workpiece support device 17 are mounted on the table 14, and the workpiece W is sandwiched between the centers of the spindle stock and the tailstock 18 and rotated. Is done.
[0015]
Reference numeral 20 denotes a dimension measuring device that measures the outer diameter dimension of the workpiece W, and is attached to the front end surface of the bed 10 via an arm 21. The dimension measuring device 20 sandwiches the processing portion of the workpiece W with a pair of movable contacts 22 and continuously measures the outer diameter of the workpiece W at a constant time interval during grinding by an internal operating transformer. The measurement result is transmitted as an electric signal to the numerical controller 23.
[0016]
A grindstone guard 29 that covers the grindstone G is fixed to the grindstone base 11, and a coolant nozzle 31 of a coolant supply device 30 is attached to the upper surface of the grindstone guard 29. The coolant supply device 30 supplies the coolant pumped up by the pump 32 to the grinding point P where the grindstone G grinds the workpiece W from the coolant nozzle 31.
[0017]
On the side plate 29b of the grindstone guard 29, an air jet nozzle 33 that opens in the horizontal direction toward the front end edge of one side face Gb of the grindstone G at a position slightly upstream of the grinding point P in the grindstone rotation direction is attached. The air jet nozzle 33 is connected to a pressurized air source 35 such as factory air via an electromagnetic opening / closing valve 34, and the air jet 36 is directed from one side Gb to the other side Gc along the grinding surface Ga of the grindstone G. The grinding stone accompanying air layer 37 that is rotated around the grinding stone G is blocked. The opening cross section of the air jet nozzle 33 is formed to be elongated in the radial direction of the grindstone G so that the air jet 36 is sprayed to the front edge of the grindstone G even if the diameter of the grindstone G is reduced by dressing.
[0018]
A wind shield plate 38 is fixed to the ceiling plate 29 a of the grindstone guard 29. An opening groove 39 is formed in the wind shielding plate 38, and the groove edge 39 a of the opening groove 39 is slightly smaller than the air jet 36 in order to block the grinding wheel-associated air layer 37 that rotates around the outer peripheral grinding surface Ga of the grinding wheel G. It extends in a direction across the outer peripheral grinding surface Ga of the grindstone G so as to face the outer peripheral grinding surface Ga of the grindstone G with a small gap at a position upstream of the grinding wheel rotation direction. Both side edges 39b, 39c of the opening groove 39 are opposed to both side faces Gb, Gc of the grindstone G with a slight gap and extend from the grinding point P to a lower position. In order to keep the minute gap between the groove edge 39a of the opening groove 39 and the outer peripheral grinding surface Ga of the grindstone G constant, the wind shield plate 38 is automatically used as the grindstone diameter decreases due to dressing of the grindstone G. You may attach to the grindstone guard 29 via a position correction mechanism so that position correction may be carried out.
[0019]
The numerical control device 23 controls the rotation of the servo motor 12 according to a grinding program to be described later, and advances the grindstone table 13 stepwise by switching to fast feed, rough grinding feed, and fine grinding feed, and performs spark-out grinding at the forward end. Therefore, after stopping for a certain time, it is retracted to the retreat end. Switching from rough grinding feed to fine grinding feed and from fine grinding feed to spark-out is performed based on the outer diameter of the workpiece W measured by the dimension measuring device 20.
[0020]
Next, the operation of the embodiment configured as described above will be described. When the workpiece W is mounted on the workpiece support device 17 and the start button is pressed (step 51), the grinding program for the workpiece W shown in FIG. 3 is executed. The workpiece W is rotationally driven by the workpiece support device 17, the table 14 is moved by the servo motor 15 via the ball screw mechanism 16, and the workpiece W is positioned at the grinding position, and the servo motor 12 via the ball screw mechanism. Then, the grinding wheel base 11 is fast-forwarded and advanced to the grinding start position immediately before the grinding wheel G contacts the workpiece W (step 52).
[0021]
The pump 32 of the coolant supply device 30 is driven, and the coolant is ejected from the coolant nozzle 31 (step 53). The electromagnetic on-off valve 34 is opened and air is supplied from the pressurized air source 35 to the air jet nozzle 33, and the air jet 36 is slightly upstream of the grinding point P in the grinding wheel rotation direction and laterally to the grinding surface Ga. It is sprayed and jets along the grinding surface Ga so as to cross from the one side of the grindstone G toward the other side (step 54). Since the air layer 37 associated with the grinding wheel rotating around the grinding surface Ga of the grinding wheel G rotating at high speed is blocked by the air jet 36 and does not reach the grinding point P, the coolant flow 41 supplied from the coolant nozzle 31 reduces the flow rate extremely. Even so, it is reliably supplied to the grinding point P without being obstructed by the air layer 37 associated with the grindstone. Since the air jet 36 traverses along the grinding surface Ga at a position slightly upstream of the grinding point P in the grinding wheel rotation direction, an air layer 37 associated with the grinding wheel is generated on the grinding surface Ga between the air jet 36 and the grinding point P. There is nothing.
[0022]
The grinding wheel base 13 is moved forward at the rough grinding feed speed, and the processed portion of the workpiece W is roughly ground by the grinding wheel G (step 55). In the rough grinding, since the grinding amount of the workpiece W by the grinding wheel G is large, in order to prevent grinding burn and thermal distortion of the processed part, the grinding stone associated air layer 37 is blocked by the air jet 36 and the flow rate is reduced. The coolant flow 41 reaches the grinding point P without being obstructed by the grinding stone-associated air layer 37, and the coolant is sufficiently supplied to the grinding point P.
[0023]
The dimension measuring device 20 is advanced toward the workpiece W, the processing portion is sandwiched between the pair of movable contacts 22, the outer diameter is measured every minute time, and the measurement result is transmitted to the numerical control device 23 (step 56). . It is determined whether or not the outer diameter has reached the first step size (step 57). If the outer diameter has been reached, the electromagnetic on-off valve 34 is closed and the ejection of the air jet 36 is stopped (step 58). The air layer 37 reaches the grinding point P without being blocked by the air jet 36, and the coolant flow 41 is deflected to the workpiece W side by the grinding wheel-associated air layer 37 and the amount of coolant supplied to the grinding point P decreases. The amount of coolant applied to the workpiece W increases. Simultaneously with the closing of the electromagnetic on-off valve 34, the feed speed of the grinding wheel base 13 is switched to the fine grinding feed speed, and the processed portion of the workpiece W is precisely ground by the grinding wheel G (step 59). At the time of fine grinding, the amount of coolant supplied to the grinding point P is reduced as described above, so the dynamic pressure generated at the grinding point by the coolant is lowered, and oil holes, grooves, etc. are cut out at the grinding location of the workpiece W. Even if there is, it is possible to prevent the dynamic pressure from changing greatly due to the notch, thereby reducing the roundness and chattering. At the same time, the amount of coolant applied to the workpiece W can be increased, the workpiece can be sufficiently cooled, and the dimensional accuracy can be improved.
[0024]
Next, it is determined whether or not the outer diameter measured by the dimension measuring device 20 has reached the second stage dimension (step 60). If so, the forward feed of the grinding wheel base 11 is stopped and the grinding wheel G is machined. The processed part of the article W is sparked out (step 61). When the spark-out grinding is performed for a predetermined time, the grindstone table 11 is retracted at the fast feed speed, the table 14 is returned to the origin position (step 62), and the workpiece W grinding program is completed.
[0025]
In the above embodiment, the electromagnetic on-off valve 34 is closed during fine grinding to stop the ejection of the air jet 36. However, the air jet nozzle 33 is connected to a pressurized air source 35 such as factory air via the electromagnetic flow control valve. When the feed of the grinding wheel base 11 is switched from the coarse grinding feed to the fine grinding feed, the opening of the electromagnetic flow control valve is reduced to reduce the flow rate of the air jet (step 58), and the grinding stone associated air layer 27 may reach the grinding point P beyond the air jet 36 according to the flow rate of the air jet 36, and control the ratio of the coolant amount supplied to the grinding point P and the workpiece W side. Further, the air flow rate may be switched at the time of fine grinding before and after fine grinding and spark out.
[0026]
In the above embodiment, the air jet 36 is sprayed so as to cross from the one side surface to the other side surface along the grinding surface Ga of the grindstone G. However, a coolant with increased coolant pressure, mist-like mist, etc. May be sprayed so as to cross from one side surface to the other side surface along the grinding surface Ga of the grindstone G to block the air layer associated with the grindstone.
[Brief description of the drawings]
FIG. 1 is a side view of a grinding machine provided with a coolant supply device according to an embodiment of the present invention.
FIG. 2 is a front view of a grindstone-associated air layer blocking device.
FIG. 3 is a diagram showing a grinding program.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Bed, 11 ... Grinding wheel stand, 12, 15 ... Servo motor, 14 ... Table, 17 ... Workpiece support device, 20 ... Dimension measuring device, 23 ... Control device, 29 ... Grinding stone guard, 30 ... Coolant supply device, 31 ... Coolant nozzle, 41 ... Coolant flow, 33 ... Air jet nozzle, 34 ... Electromagnetic on-off valve, 35 ... Pressurized air source, 36 ... Air jet, 37 ... Air layer associated with grinding wheel, 38 ... Wind shield, W ... Workpiece .

Claims (3)

Grinding of the grinding wheel while feeding the grinding wheel supported by the grinding wheel table and rotating relative to the workpiece driven by the workpiece support device and supplying coolant to the grinding point In a coolant supply method in a grinding machine that grinds the workpiece by a surface, a fluid jet is used to shut off the air layer associated with the grindstone that rotates around the grindstone at a position upstream of the grinding point in the grindstone rotation direction. A fluid jet nozzle that sprays along the grinding surface of the grinding wheel from one side to the other side is provided, and when the amount of coolant supplied to the grinding point is reduced , the jet of fluid is stopped. Alternatively, a coolant supply method in a grinding machine, wherein the flow rate is reduced.   In Claim 1, when rough-grinding the workpiece with the grinding surface of the grinding wheel, the fluid jet is used to block the air associated with the grinding wheel, and the coolant is not inhibited by the air associated with the grinding wheel. A coolant supply method for a grinding machine, characterized in that when supplying to a grinding point and finishing grinding, the amount of coolant supplied to the grinding point is reduced by stopping or reducing the flow rate of the fluid jet. Grinding of the grinding wheel while feeding the grinding wheel supported by the grinding wheel table and rotating relative to the workpiece driven by the workpiece support device and supplying coolant to the grinding point In a grinding machine that grinds the workpiece by a surface, a fluid jet is ground on the grinding surface of the grindstone in order to block an air layer associated with the grindstone that rotates around the grindstone at a position upstream of the grinding point in the grinding wheel rotation direction When a fluid jet nozzle is sprayed so as to traverse from one side to the other side along the surface of the nozzle, and the amount of coolant supplied to the grinding point is reduced , the fluid jet is stopped or the flow rate is reduced. A grinding machine characterized by providing means.

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