JPS6232769Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a feed system used when grinding a workpiece with a grindstone, and more specifically relates to a surface grinder in which the feed system is equipped with a minute cutting mechanism.

Conventionally, in order to obtain extremely excellent surface roughness in grinding using a surface grinder or the like, it is necessary to make minute cuts of 1 μm or less in the final finishing step. However, in the structure of current grinding machines, the feed system structure that cuts into the workpiece has a considerable weight (approximately 220 kg), so when it is driven by a feed screw, etc., the feed screw has the above-mentioned weight. Grinding is always performed in an unstable feed state, that is, in a cutting state, because loads such as stake slip generated from the sliding guide surface of a heavy structure and grinding force accompanying machining are applied.

For this reason, conventional feed systems have a feed rate of 1 μm or less.
In other words, it was extremely difficult to obtain the cuts with high repeatability.

Therefore, in this invention, we have realized highly accurate positioning by compensating for the sliding resistance of the sliding guide surface, that is, the load such as the stick slip and the grinding force associated with machining.
The aim is to drive the feed system while maintaining this highly accurate positioning state so as to be able to repeatedly obtain highly accurate minute feeds, ie cuts, and will be detailed below with reference to FIGS. 1 to 3 showing examples. .

In the figure, reference numeral 1 denotes a bed of a surface grinding machine, and a column 3 on which a grindstone shaft head 2 is mounted so as to be slidable in the direction of the arrow shown in the figure is mounted on the bed 1.
The structure of the sliding guide surface between the column 3 and the grinding wheel shaft head 2 described above consists of two concave surfaces 3a formed on the column 3 side,
3b is engaged with the jaws 2a, 2b on the grinding wheel shaft head 2 side, and the clamp plates 3d, 3e are configured to prevent the jaws 2a, 2b of the grinding wheel shaft head 2 from rising from the concave surfaces 3a, 3b. .

A main shaft 4 is rotatably supported on the grindstone shaft head 2, and a grindstone 5 is attached to the tip side of the main shaft 4. Further, a drive motor 7 is connected to the rear end side via a coupling ring 6. A pressure response device, such as a hydraulic cylinder 8, is attached below the grindstone shaft head 2, and a feed screw 9 is attached to a piston rod 8a of the hydraulic cylinder 8. This feed screw 9 is threadedly engaged with a feed nut 10 rotatably mounted on the bed 1 side, and this feed nut 10 is adapted to be rotated by a series of gear trains 11. This series of gear trains 11 is rotated by a drive shaft 12 connected to a feed drive system (not shown).

A gear box 13 is installed above the grinding wheel shaft head 2, and a feed nut 1 is mounted inside this gear box 13.
A series of gear trains 15 are built in to rotate the motor. An electric pulse motor 26 driven by a command pulse signal issued from a control device (not shown) is connected to one gear of a gear train 15 built in the gear box 13. A highly precisely finished feed screw 17 is screwed into the above-mentioned feed nut 14, and this feed screw 17 is connected to a strain gauge 18 attached to a shaft 16 exposed from the inside of the column 3 to the outside. There is. Shaft 1 exposed to the outside from this column 3
A collector member 19 is engaged with the outer periphery of 6,
In addition, this collector member 19 is mounted on the column 3. Central threaded portion 19 of collet member 19
A collet nut 20 is screwed into the collet nut 20, and a rack 21 operated by a drive system (not shown) meshes with an outer peripheral gear 20a of the collet nut 20. Note that a servo valve 22 is connected to the ports a and b of the hydraulic cylinder 8 described above, which receives pressure oil from a hydraulic pressure supply source Ps. A servo amplifier 23 that supplies a predetermined current to a torque motor (not shown) built in the servo valve 22 is connected to the servo valve 22 described above.
3 is connected to a phase lag compensation circuit 24. The compensation circuit 24 also includes the strain gauge 1 described above.
A voltage amplifier 25 connected to 8 is connected. The compensation circuit 24 described above is, for example, a strain gauge 1
If a displacement occurs in 8, immediately set the displacement to "zero".
An electric signal is generated to operate a torque motor (not shown) of the servo valve 22 in order to apply a differential pressure to the hydraulic cylinder 8 as shown in FIG. Finally, numbers 27 and 28 indicate bellows for preventing grinding powder, dust, etc. from entering and adhering to the gear train 11 in the column 3.

Next, the operation of the above configuration will be explained. First, when a start button (not shown) is pressed, the drive motor 7 for the grindstone shaft 2 is driven. This causes the main shaft 4 to rotate and the grindstone 5 to rotate. As the drive shaft 12 rotates, the feed nut 10 rotates via the gear train 11.
As the feed screw 9 is lowered by this rotation of the feed nut 10, the grindstone shaft head 2 is lowered via the piston rod 8a of the hydraulic cylinder 8, and rough positioning with respect to the workpiece (not shown) and normal grinding are performed. It will be done.

Next, from this positioning state, the shaft 1 on the grinding wheel shaft head 2
6 is fixed to column 3 by the following operation.

That is, as the rack 21 on the column 3 operates, the collet nut 20 with the gear 20a rotates, so that the thread formed therein engages with the threaded portion 19a of the collet member 19 and descends, causing the taper portion of the collet nut 20 to rotate. is collect member 1
A shaft 16 is fixed in order to press the tapered portion of 9.

In this state, when a command pulse is given to the electric pulse motor 26 from a control device (not shown), the pulse motor 26 is driven to rotate the gear train 15.
As a result, the feed nut 14 rotates and the grinding wheel shaft head 2
(Whetstone 5) is slightly fed in the downward direction, that is, it is made to make a fine cut. At this time, the weight of the grindstone shaft head 2 suspended on the feed screw 17 is detected as a displacement by the strain gauge 18, and this detected electrical signal is sent to the phase lag compensation circuit 24 via the voltage amplifier 25. The electric signal output from the compensation circuit 24 is sent to the servo valve 22 via the servo amplifier 23, and upon receiving this signal, the torque motor (not shown) of the servo valve 22 immediately adjusts the amount of displacement corresponding to the signal. Hydraulic cylinder 8
A differential pressure is applied to compensate for the weight of the grinding wheel shaft head 2.

As described above, the present invention adds a hydraulic servo-controlled load compensation mechanism to the screw feed system that makes a cut into the workpiece, so that the load fluctuation factor applied to the screw feed system as in the conventional method is replaced by the load compensation mechanism described above. Therefore, it is possible to compensate
Since the screw feeding system only needs to share the inherent feeding accuracy, it has the effect of being able to perform overall high rigidity and highly accurate minute feeding, that is, minute cutting.

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing the surface grinder of the present invention;
Figure 2 is a sectional view taken along the - line in Figure 1;
The figure is a sectional view taken along the - line in FIG. 1. 1...Bed, 2...Whetstone shaft head, 3...Column, 4...Main shaft, 5...Whetstone, 6...Drive motor, 8...Hydraulic cylinder, 8a...Piston rod, 9, 17...Feed Screw, 10, 14...Feed nut, 16...Shaft, 18...Strain gauge, 2
2... Servo valve.

Claims (1)

[Scope of utility model registration request] As a moving mechanism for moving the grinding wheel shaft head along the sliding surface of the column fixed on the bed, there is a coarse feed screw feeding mechanism connected to the first drive section and also connected to the pressure response device, and a second drive section. a screw feeding system for precision feeding connected to a load detector provided at one end of a shaft protruding from the upper end of the column; and a shaft protruding from the upper end of the column above the column. a fastening device for fixing the pressure-responsive device and a load detector;
The coarse feed screw feed mechanism uses a fixed rotary drive to roughly position the grindstone shaft head and operates the fastening device to fix the shaft, and the precision feed screw feed mechanism uses a rotary drive to roughly position the grindstone shaft head during precise positioning. A surface grinding machine equipped with a minute cutting mechanism, characterized in that the pressure responsive device is hydraulically servo controlled to compensate for the load so that the load generated on the detector becomes zero.