JPS5997825A - Workpiece fixing board for machine tool - Google Patents

Abstract

PURPOSE:To correct the elastic deformation when fixing a workpiece by installing a reference receiving frame on the front surface of a base board, providing a pair of workpiece clamps on each side of said base board, installing a deformation correcting device on the back side thereof, while pressing and spreading the back side of the base board in the direction of clamps. CONSTITUTION:A workpiece fixing plate P consists of a steel base board 6, a reference receiving frame 7, and more than one workpiece clamp 8. The reference receiving frame 7, for continuous string member is transferrably fixed, being faced in the right and left direction, using T-grooves and bolts, in the central part of the workpiece mounting surface 12 which is the upper surface U of the base board 6, and workpiece receiving faces 14 are provided on both front and back sides of the receiving frame 7. String-member clamp bodies 8A are transferrably fixed to the workpiece mounting surface 12 with a T-nut 15 and a fixing bolt 16 respectively. Deformation correcting devices M for correcting the elastic deformation of the base board 6 are provided on the back side of the base board 6. Wedged members 21 which constitute the deformation correcting devices M are retractably fitted in tapered recesses provided on the back of the base board 6, to correct elastic deformation by retractingly driving the wedged members 21.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a workpiece fixing plate for positioning and fixing a workpiece processed with a machine tool with high precision.

In machine tools, especially the latest NC machine tools, in order to increase the operating rate of the machine, workpieces are exchanged using a workpiece fixing plate that positions and fixes the workpiece. In particular, the workpiece fixing platen PVi for vertical machine tools, the platen 6 as shown in Figure 8.
A work clamp 8 and a reference receiving frame 7 are attached to the 0 surface so as to face each other in the front and back, and the work W is clamped and fixed between the two.

At this time, a bending moment is applied to the base plate 6 due to the reaction force of the crack/guka, and the base plate 6 is elastically deformed and warped into a mid-height shape.

In the case of a normal thick workpiece fixing platen, what is the maximum displacement that results in this elastic deformation? -1100 to 200 microns, which has a significant negative effect on the machining finish accuracy of the workpiece. Therefore, in the case of precision mechanical parts that require precision on the order of microns, this can cause defective products.

In addition, modern machine tools are designed to reduce the weight of the table, so the rigidity of the table is not very large.
Even if the base plate of the workpiece fixing plate is strongly fixed to the table at multiple locations, it is difficult to correct the elastic deformation of the base plate.

In addition, if the base plate is made thick and rigid in order to reduce the amount of elastic deformation of the base plate, the weight of the workpiece fixing plate will increase, increasing the load on the table of the machine tool.
There are many disadvantages, such as the base plate being expensive.

Conventionally, horizontal MCs (machine/guse/ter) have used a type in which a workpiece is directly fixed to the workpiece mounting surface of a box-shaped workpiece fixing frame with bolts or the like, so the above problem does not occur.

In NC vertical machine tools, the above-mentioned work fixing platen has hardly been put into practical use, so the above-mentioned problems are completely unknown, and therefore, the means for solving them are also completely unknown.

In view of the above-mentioned drawbacks, the present invention has been developed by attaching a reference support frame to the work mounting surface on the surface of the base plate of the work fixing plate, placing a work clamp on one side at least, and attaching it to the back side of the base plate. This deformation correction device is capable of correcting the elastic deformation of the base when a workpiece is fixed by pushing and expanding the back side of the base in the clamping direction. In addition, by using a deformation correction device consisting of a wedge mechanism, the magnification factor is increased by 3 - to make the deformation correction device more compact, and its structure is simplified to increase durability, making it easy and inexpensive to implement. It has been made possible.

Embodiments of the present invention will be described below based on the drawings.

The main embodiment is shown in Figs. 1 to 5, and Fig. 1 shows the machine tool (
FIG. 2 is a perspective view of the workpiece fixing plate positioning device T and the workpiece fixing plate P of table 7 (not shown), and FIG. 2 is a bottom view of the workpiece fixing plate P.

After attaching and detaching the workpiece to the workpiece fixing plate P at the exchange stand (not shown) J installed on the front side of the machine tool, the positioning fixing device T
After transporting the workpiece to the machine, positioning it, and fixing it, the workpiece is machined. This positioning and fixing device T includes rails 1 of the conveyance path.
, a stopper 2 for receiving and locking, a traveling guide 5, a pair of underframe devices 4 for positioning the workpiece fixing plate P, and six sets of clamp devices 5 for fixing the workpiece fixing plate P are attached. ing.

The workpiece fixing plate P consists of a steel base plate 6, a reference support frame 7, and a plurality of work clamps 8, and the backside IVcp of the base plate 6
, a traveling guide groove 9, three clamp T-grooves 10 through which the clamp arm 5a of the clamp device 54 is inserted and locked, and a traveling device mounted in the two square grooves 1,1.

A reference receiving frame 7 made of a continuous strip is movably fixed to the center of the workpiece mounting surface 12 on the surface U of the base plate 6 in the left-right direction using a fixing bolt using a T-groove 15, and the workpiece receiving surface is provided on both front and rear sides of the reference frame 7. 14 is formed.

7. The clamp main body 8A in the form of a single strip is placed on the workpiece mounting surface 1 in a state facing both the workpiece receiving surfaces 14 with a workpiece placement space left therebetween.
It is movably fixed by a T-nut 15 in the 2vc% T-groove 15 and a fixing bolt 16.

Each clamp body 8 AK 9 sets of hydraulic work clamps 8
are attached toward the reference receiving frame 7 at regular intervals. That is,
A pressure oil supply hose from an external oil pressure supply device is connected to the oil pressure supply port 17 to supply pressure oil, and this pressure oil is supplied to each hydraulic cylinder/cylinder in the clamp body 8A, and then to the tip of each piston rond. The connected clamp tool 18 is driven forward toward the work receiving surface 14, and the VC is configured to fix the '7-ri W between the work receiving surface 14 and the clamp tool 18.

Incidentally, by releasing the pressure oil from the hydraulic cylinder to the clap tool 18, it is moved back by the return spring.

In order to position the workpiece W on the workpiece fixing plate P with high precision in the front-rear direction and the left-right direction, both workpiece receiving surfaces 14 are formed in parallel with high precision flat shapes, and are not only subjected to induction hardening treatment. By pressing symmetrically from both sides 1i11 of the reference receiving frame 7, deformation of the reference receiving frame 7 is prevented. Therefore, the relative position of the workpiece receiving surface 14 with respect to the workpiece mounting surface 12 does not change, so by bringing the flat side surface of the workpiece W into contact with the workpiece receiving surface 14, the longitudinal position of the workpiece W can be adjusted. Highly accurate positioning is possible.

In addition, a gate-shaped positioning tool 19 is removably inserted into square grooves formed at regular intervals on the upper surface of the reference receiving frame 7, and the positioning tool 19 can be used to accurately determine the horizontal position of the workpiece W. can.

Next, the deformation correction device M will be explained in detail with reference to FIGS. 2 to 5.

The base plate 6 is made of a steel master plate and has great rigidity, but since a large number of work clamps 8 with a pressing force of about 3 tons are arranged side by side, as mentioned above, when the work is clamped,
The base plate 6 is elastically deformed by about 100 to 200 microns at the displaced position of its central portion, as shown in FIG.

The elastic deformation of the base plate 6 is corrected by the following deformation correction device M. That is, as shown in FIGS. 2 and 3, two wedge-shaped gaps 20 are formed between each groove on the rear surface l side of the base plate 6 in a direction perpendicular to the clamping direction (horizontal direction). From the back L side to the front U
Each wedge tool 2 is provided in a tapered shape toward the side, and each wedge tool 2 is provided in each wedge-shaped gap 20.
1 is inserted and retracted freely, and each wedge tool 21 is moved to the back of the wedge-shaped gap 20 by the hydraulic cylinder 22 of the driving means, that is, the wedge-shaped gap 2
It is possible to freely drive to the opening angle expansion side of 0.

The hydraulic cylinders 22I/'i are formed in the base plate 6 at the center and side of each wedge-shaped gap 20, and are supplied with pressure oil from the oil passages 2!1 in the base plate 6 to move the pistons/24 upward. , piste/
The wedge tool 21 connected to the tip of the rod 25 can be moved upward.

The oil passage 25 communicates with an oil passage (not shown) K to the work clamp 8, and the hydraulic cylinder 22 operates only when supplying pressure oil to the work clamp 8 to clamp the work W. is pulled into the depths of the wedge-shaped gap 20 and driven.
A reverse bending moment is added to correct the elastic deformation of the base plate 6 due to the work clamp 8.

When the pressure oil in the work clamp 8 is removed, +711, the wedge tool 21 is pushed back to the outside of the wedge-shaped gap 20 by the elastic restoring force of the elastic deformation of the base plate 6 and the spring force of the return spring 26 in the hydraulic cylinder 22. This allows the board 6 to return to its normal shape without deformation.

It is desirable to coat the passive slope 27 of the wedge-shaped gap 20 and the wedge tool 21 with a low-friction synthetic resin material, or to increase their hardness by subjecting them to a nitriding treatment. It is also conceivable to form at least one of the slopes 28 from oil-impregnated sintered metal. Furthermore, wedge tool 21
It is also conceivable to incorporate a roller bearing 29 or a ball bearing into the main driving slope 28 as shown in FIG.

The smaller the friction coefficient between the active slope 28 and the passive slope 27 is, the more advantageous it is that the opening angle of the wedge-shaped gap 20 can be reduced and the power factor can be increased.

If the wedge tool 21 does not return to the outside when the work clamp 8 is not operated, the base plate 6 will be elastically deformed into a mid-low shape by the deformation correcting device M, and in this state, the work W will be attached to the work fixing plate 6. 1, which may cause errors.
It's not right.

Here, regarding the force to be applied by the deformation correction device M, the fifth
This will be explained using figures.

The reaction force of the clamp 71 received by the work clamp 8 is fl.

The opening angle of the wedge-shaped gap 20 is 2θ, the rod output of the hydraulic cylinder 22 is P, the force that the passive slope 27 receives from the wedge tool 21 is F,
If the horizontal component of F is f2, then F=0゜5P/sinθ
, f2=0.5P/lanθ.

In order to correct the elastic deformation caused by the work clamp 8, f
It is necessary to set so that IX a = f2X b. However, a and b are moment arms of fl and f2 from the neutral axis NA of the base plate 6, respectively.

Incidentally, even when adjusting the hydraulic pressure of the pressure oil supplied to the work clamp 8 as appropriate to adjust the clamping force according to the material and shape of the workpiece W, since the oil passage 25 is in communication, the clamping force can be adjusted according to the hydraulic pressure. The hydraulic cylinder 220 rod output P is adjusted.

In addition, the deformation correction device MU is not limited to 2 articles, but 1 article, or 3 articles,
Four threads may be provided, and the more threads there are, the smoother the elastic deformation can be corrected.

Hereinafter, a part of the above embodiment can be modified as follows.

(1) As shown in FIG. 7, a double-acting hydraulic cylinder is used as the driving means.

(2) The hydraulic cylinder 22 is omitted, and the wedge tool 21 is driven by a bolt-type fastener (not shown) screwed onto the base plate 6.

(3) A wedge-shaped gap is provided between the protrusions on the back surface 11111 of the base plate 6.

Since the present invention is configured as described in item ah, the following effects are achieved.

(5) A reference receiving frame is provided on the workpiece mounting surface of the base plate of the workpiece fixing plate, a workpiece placement space is left on at least one side of the frame, workpiece clamps are placed oppositely, and the workpiece is clamped and fixed to the reference receiving frame by the workpiece clamp. , the platform bends back into a mid-height shape and deforms elastically. Therefore, a deformation correction device is attached to the back side of the base plate, and this device pushes and expands the back side of the base plate in the clamping direction to correct the elastic deformation of the base plate when the work is clamped. Even in this state, the base plate can be held in its regular shape without elastic deformation, and the workpiece mounting surface of the base plate can be held in a perfect plane, similar to the state in which the crane is released. Therefore, (1) The machining accuracy of the workpiece is greatly improved, and the occurrence of defective products can be prevented.

(2) When the base plate of the workpiece fixing plate is fixed on the table of the machine tool, the table will not be deformed, so there will be no adverse effect on the table side.

(3) According to the elastic deformation of the base plate during clamping, this can be corrected by the deformation correcting device, so the thickness of the base plate can be reduced, the weight can be reduced, and the price can be reduced. .

However, the deformation correction device has a structure in which a wedge tool is inserted into a wedge-shaped gap provided on the back side of the base plate, and this wedge tool is driven by a driving means to the side where the opening angle of the wedge-shaped gap is expanded.

Since the power factor of the wedge mechanism is also increased, the deformation correction device can not only be made smaller overall, but also have a simple structure, reliable operation, excellent durability, and a simple and inexpensive implementation.

[Brief explanation of drawings]

1 to 7 show an embodiment of the present invention, and FIG. 1 is a perspective view of a workpiece fixing plate positioning and fixing device and a workpiece fixing plate;
FIG. 2 is a bottom view, FIG. 3 is a vertical sectional side view of a main part, and FIG. 4 is an enlarged vertical sectional side view of a main part. Figure 5 is an explanatory diagram of the mechanical mechanism, Figure 6 is a perspective view of a wedge tool in a modified example, Figure 7 is a diagram equivalent to Figure 4 in another modified example, and Figure 8 is a deformed state of the workpiece fixing plate. It is an explanatory diagram. 6. Base plate, 7. Reference support frame, 8. Work clamp. 12...Work mounting surface, 18...Work clamp tool,
12- 20... Wedge-shaped gap, 21... Wedge tool, 22... Hydraulic cylinder, 25... fltlM, P... Work fixing plate, W...
Workpiece, D... Drive means, U... Surface, 7?・・Back side,
M...Deformation correction device.

Claims (1)

[Claims] 1. A ULC work mounting surface is provided on the base plate 6 of the '7-1 stationary plate P, and a reference receiving frame 7 is attached to the work mounting surface 12, and at least one surface on the front and rear of the reference receiving frame 7 is provided. Place the work clamp 8 on the work mounting surface 1 with a work placement space left on one side.
2, the workpiece flanging tool 18 of the workpiece clamp 8 is configured to be freely driven forward and backward toward the reference receiving frame 7, and the back side portion of the baseplate 6 is pushed out toward the back l side of the baseplate 6 in the clamping direction. Equipped with deformation correction device M, work clamp 8
The workpiece W is placed between the workpiece clamping tool 18 and the reference frame 7.
The elastic deformation of the base plate 60 when clamped and fixed can be corrected by the deformation correction device M, and the deformation correction device MIf'i,
Consisting of a wedge-shaped gap 20, a wedge tool 21, and seven drive means, one is located on the back side of the board 6! A wedge-shaped gap 20 along the direction orthogonal to the clamping direction is provided in a tapered shape from the back side L side to the front side U side of the base plate 6, and a wedge tool 21 is inserted into this wedge-shaped gap 20 so as to be freely retractable. A workpiece fixing plate 2 for a machine tool, characterized in that the tool 21 can be driven to the widening angle side of the wedge-shaped gap 20 by a drive means, and a workpiece for the machine tool as set forth in claim 1 of the utility model registration claim. In a fixed plate, a single-acting hydraulic cylinder 22 is used as a driving means, and an oil passage 23 of this hydraulic cylinder 22 is communicated with an oil passage to a hydraulic work clamp 8.3, Utility Model Registration Claim 1 or In the workpiece fixing plate of the machine tool described in Section 2, the wedge-shaped gap 20 is recessed on the back surface l (1111) of the base plate 6.