JPH0521682B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a processing device equipped with a rotating cutting tool, sometimes including a rotating main shaft with a cutting tool attached to the tip, and a processing device that moves a workpiece to intersect with the axis of the main shaft. This invention relates to a processing device that processes a workpiece by moving it in a direction.

<Prior art> In a processing device that processes the processed surface of a polygon mirror having a plurality of processed surfaces on its outer circumferential surface using a cutting tool attached to the tip periphery of a rotating main shaft, the force applied to the cutting tool during cutting is constant. One workpiece surface is machined by moving the workpiece support base supporting the workpiece in a specific direction so that the workpiece is in the direction of The object support table is moved in the opposite direction to the specific direction and returned to its original position so that the workpiece is always fed in the same direction during processing.

By the way, if such a return operation is performed without releasing the cutter, a cutter return mark will be left on the workpiece surface, so the workpiece support or headstock should be able to move forward and backward, and the workpiece support or headstock should be moved back and forth when the workpiece support is returned. A fixed position stop mechanism is provided that moves the table relatively backward or indexes the spindle to a specific phase in which the cutter does not engage with the workpiece when moving the workpiece, and when the workpiece support is returned, the spindle is moved to the specified position. It is necessary to index the phase of

<Problems to be Solved by the Invention> However, in the former method, there is a problem that machining accuracy deteriorates due to the increase in the number of guide surfaces, and in the latter method, the main spindle must be rotated before returning the workpiece support. It is necessary to stop the spindle at a fixed position, restart the spindle and wait until the spindle reaches the desired rotational speed when cutting feed is started, resulting in problems such as a longer cycle time.

<Means for solving the problem> The present invention rotatably supports a main spindle on a headstock,
In a processing device that processes a workpiece by attaching a cutting tool to the tip of the main spindle and moving the workpiece in a direction intersecting the rotational axis of the main spindle while rotating the main spindle, a cutting tool is attached to the tip of the main spindle. A flange portion is provided at a position that protrudes in the radial direction and does not restrict movement toward the cutting tool side, and a movable cylinder that protrudes in the radial direction of the spindle is provided on the spindle, and the spindle is thrust supported between the opposing surfaces of the flange portion and the headstock. A hydrostatic fluid thrust bearing is installed between the movable tube and the headstock to increase the thrust force acting on the workpiece toward the workpiece as the gap between the opposing surfaces of the flange and the headstock becomes smaller. A cylindrical cylinder chamber is formed that generates a pressing force on the opposite side of the workpiece, and during the process of moving the workpiece while cutting the workpiece, a low pressure is supplied to the cylinder chamber. A fluid pressure control means is provided for moving the main shaft to the forward position and supplying high pressure to the cylinder chamber during the return process of the workpiece to move the main shaft to the retreat position.

<Examples> Examples of the present invention will be described below based on the drawings. In FIG. 1, 10 is a spindle supported on a headstock 11, 12 is a tool support attached to the tip of the spindle 10, and the outer edge of the tip of this tool support 12 is made of a diamond cutting tool or the like. The cutter T is attached. The main shaft 10 is connected via a pulley and a belt to a main shaft motor 15 which is placed separately from a bed 13 on which a headstock 11 is mounted, and is rotated.

On the other hand, 20 indicates the headstock 1 on the bed 13.
A cross feed table 20 is guided and supported so as to be movable in a direction orthogonal to the spindle axis at a position opposite to the main shaft axis, and is moved by an unillustrated cylinder device. A cutting table 23 that moves in a direction parallel to the axis is placed, and a workpiece support 25 having an indexing function is placed on this cutting table 23.

This workpiece support stand 25 is a workpiece support stand main body 26
Above, a rotating shaft 2 that is rotationally indexed around a vertical axis.
7, and a workpiece W such as a polygon mirror having a large number of workpiece surfaces on its outer circumferential surface is attached to the upper end of the rotating shaft 27.

Next, the support mechanism for the main spindle 10 will be explained. As shown in FIG. A plurality of pockets 32 and 33 are formed on the inner periphery of the pocket 31 to generate thrust in the radial direction.
33 are communicated with an oil passage 37 via fixed throttles 35a, 35b and annular passages 36a, 36b, respectively. This oil passage 37 is connected to the output of a pump 39 whose output is controlled to a predetermined pressure P1 by a relief valve 38, and fluid at pressure P1 is supplied to the pocket 3 through the fixed throttles 35a and 35b.
2,33. Mainly the plurality of pockets 32, 33, fixed aperture 35a,
35b constitutes a hydrostatic fluid radial bearing that radially supports the main shaft 10.

Further, among the bearing metals 30 and 31, on the end surface of the bearing metal 30 near the tip side of the main shaft 10,
An annular thrust pocket 40 facing the flange portion 10a integrally formed at the tip of the main shaft 10
is formed, and the opposite end of the bearing metal 30 is fitted into an annular recess 42 formed in the end face of the movable cylinder 41 fixed to the main shaft 10, so that a gap is formed between the bearing metal 30 and the movable cylinder 41. A cylinder chamber 43 is formed. The area of the end surface where the thrust pocket 40 is formed is larger than the area of the end surface of the bearing metal 30 located inside the cylinder chamber 43, and an annular recess 45 for fluid recovery is provided on the inner periphery of the thrust pocket 40. is formed.

The thrust pocket 40 is communicated with the oil passage 37 via a fixed throttle 44, a communication passage 46, and an annular groove 36a, and the cylinder chamber 43 is communicated with a pair of oil passages via a communication passage 48, an annular groove 49, and a passage 50. The output side of the electromagnetic on-off valves 51 and 52 are communicated with each other. Of the electromagnetic on-off valves 51 and 52, the electromagnetic on-off valve 51 is connected to the pump 39 via a pressure reducing valve 53 whose set pressure is set to P2, and the electromagnetic on-off valve 52 is connected to the output of the pump 39. connected directly to.

Note that the set pressure P2 of the pressure reducing valve 53 is set to, for example, about 2/3 to 1/2 of the set pressure P1 of the relief valve 38. The thrust pocket 40 and the fixed throttle 44 mainly constitute a hydrostatic fluid thrust bearing that supports the main shaft 10 in thrust.

Reference numeral 60 denotes a sequence control device that controls the operation of the lathe configured as described above, and as shown in the flowchart of FIG. The on-off valve 52 is deenergized and the solenoid on-off valve 51 is energized.
2 is energized.

When the electromagnetic on-off valve 51 is energized, pressure fluid whose pressure is reduced to pressure P2 by the pressure reducing valve 53 is supplied to the cylinder chamber 43, so that the pressure supplied to the cylinder chamber 43 is supplied to the thrust pocket 40. The value is low for the pressure applied.

Therefore, the main shaft 10 advances toward the workpiece W,
The front end surface of the bearing metal 30 and the flange portion 10 of the main shaft 10
The distance between a and a increases, and the thrust of the thrust pocket 40 (hydrostatic thrust bearing) decreases. A state in which the pressing force by the cylinder chamber 43 and the thrust by the thrust pocket 40 are balanced, that is, the front end surface of the bearing metal 30 and the flange portion 10 of the main shaft 10
The forward movement of the main shaft 10 stops when the distance between the main shaft 10 and the main shaft 10 reaches d1. Since there is nothing that restricts the movement of the flange portion 10a of the spindle 10 toward the workpiece W, the spindle 10 can be advanced until the end surface of the movable cylinder 41 comes into contact with the end surface of the bearing metal 30. The amount of movement of the main shaft 10 can be increased.

On the other hand, when the electromagnetic on-off valve 52 is energized instead of the electromagnetic on-off valve 51, the fluid at the pressure P1 from the pump 39 is also supplied to the cylinder chamber 43.
The pressure inside the cylinder chamber 43 increases from P2 to P1. As a result, the main spindle 10 retreats to the side opposite to the workpiece W, the distance between the front end surface of the bearing metal 30 and the flange portion 10a of the main spindle 10 becomes smaller, and the thrust pocket 40 (hydrostatic thrust bearing) thrust increases. The main shaft 10 stops retreating when the pressing force from the cylinder chamber 43 and the thrust from the thrust pocket 40 are balanced, that is, when the distance between the front end surface of the bearing metal 30 and the flange portion 10a of the main shaft 10 reaches d2. In this way, even if the electromagnetic on-off valves 51 and 52 are operated while the main shaft 10 is rotating,
Since the thrust pocket 40 is constantly supplied with pressure oil from the pump 39, the function of the hydrostatic fluid thrust bearing does not stop. In addition, if the cutting tool T on the main spindle 10 is moved back by a minute amount, the workpiece support 25
In the process of returning the cutting tool T to the original position, it is possible to prevent the cutting tool T from making a mark on the workpiece surface of the workpiece W.

<Effects of the Invention> As described above, in the present invention, a flange portion is provided on the spindle at a position that protrudes in the radial direction of the spindle and does not restrict movement toward the cutting tool side, and a movable portion that protrudes in the radial direction of the spindle is provided on the spindle. A cylinder is provided to thrust support the spindle between opposing surfaces of the flange portion and the headstock, and as the gap between the opposing surfaces of the flange portion and the headstock becomes smaller, the thrust acting on the spindle toward the workpiece is reduced. A cylindrical cylinder chamber is provided between the movable cylinder and the headstock to generate thrust toward the workpiece and the opposite object, and a cylindrical cylinder chamber is provided between the movable cylinder and the headstock to increase the static pressure. In the process of moving the workpiece, low pressure is supplied to the cylinder chamber to move the main shaft to the forward position, and in the process of returning the workpiece, high pressure is supplied to the cylinder chamber to move the main shaft to the backward position. Since the structure is equipped with a fluid pressure control means for moving the workpiece support, it is possible to release the cutting tool during the return process of the workpiece support without deteriorating machining accuracy or increasing the machining cycle time. This has the advantage of being able to perform highly accurate machining with high efficiency.
Further, the main shaft is moved forward by the pressing force of the pressure oil supplied to the cylinder chamber, and since there is nothing to restrict the forward movement of the flange portion of the main shaft, the amount of movement of the main shaft can be increased.

Moreover, the pressure of the pressure oil supplied to the cylinder chamber is changed, and the hydrostatic thrust bearing is constantly supplied with pressure oil from the pump, so the function of the hydrostatic thrust bearing stops while the main shaft is rotating. Never.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view showing the overall configuration of the processing device, and FIG.
A diagram in which the control circuit is also shown in the cross-sectional view taken along the - line in the figure, and Figures 3a and b are the main shaft 10 in Figure 2.
FIG. 4 is a flowchart showing the operation of the sequence control device in FIG. 2. 10... Main spindle, 11... Headstock, 12... Tool support, 20... Cross feed table, 25... Workpiece support stand, 30... Bearing metal, 38... Relief valve, 39
...Pump, 40...Thrust pocket, 43...
... Cylinder chamber (pressure chamber), 51, 52 ... Solenoid on-off valve, 53 ... Pressure reducing valve, T ... Cutting tool, W ... Workpiece.

Claims (1)

[Claims] 1. A main spindle is rotatably supported on a headstock, a cutter is attached to the tip of the main spindle, and the workpiece is moved in a direction intersecting the rotational axis of the main spindle while rotating the main spindle. In the processing device, a flange portion is provided on the spindle at a position that protrudes in the radial direction of the spindle and does not restrict movement toward the cutting tool side, and a movable cylinder that protrudes in the radial direction of the spindle is provided on the spindle, and the flange portion and A hydrostatic fluid thrust bearing that thrust-supports the spindle between opposing surfaces of the headstock and increases the thrust acting on the spindle toward the workpiece as the distance between the flange and the opposing surfaces of the headstock becomes smaller. is provided, and a cylindrical cylinder chamber is formed between the movable cylinder and the headstock to generate a pressing force on the main shaft toward the side opposite to the workpiece, and in the process of moving the workpiece while cutting the workpiece. fluid pressure control that supplies low pressure to the cylinder chamber to move the spindle to a forward position, and supplies high pressure to the cylinder chamber to move the spindle to a retreat position in the process of returning the workpiece; A processing device equipped with a rotary cutting tool, characterized in that a means is provided.