JP2006088230A - Machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machine tool having a vertical mover moving in the vertical direction, reducing quadrant projection due to follow-up delay of a counter balancer when the moving direction is reversed without remarkable increase in cost to heighten the working accuracy. <P>SOLUTION: The machine tool includes: a Y-axis mover 20 movable in the Y-axis direction (in the vertical direction); a counterbalancer 24 for removing the influence of the gravity applied to the Y-axis mover 20; and a buffer means 29 disposed between the counterbalancer 24 and the Y-axis mover 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a machine tool, and more particularly to a machine tool including a counter balancer for removing the influence of gravity of a vertical moving body that moves in a vertical direction.

  2. Description of the Related Art Conventionally, machine tools having a counter balancer that supports a tool or a workpiece and removes the influence of gravity of a vertical moving body that moves in the vertical direction are known. By supporting the gravity applied to the vertical moving body by this counter balancer, the weight of the vertical moving body is prevented from being applied to the feed driving means for moving in the vertical direction, and the load on the feed driving means is reduced. Thus, it is possible to improve the processing accuracy and downsize the feed driving means.

  As this counter balancer, for example, a balance weight having substantially the same weight as the vertical direction moving body is provided so as to be movable in the vertical direction, and the balance weight and the vertical direction moving body are connected by a wire or the like via a pulley. The thing of the form which supports the weight of a vertical direction moving body is known.

  However, since the above-described configuration requires a balance weight and a space for moving the balance weight, there is a problem that the entire machine tool is increased in size. Moreover, since the mass of the balance weight is added in addition to the mass of the vertical moving body, there is a problem that the moving mass increases and becomes worse. Therefore, in order to make it small and have good controllability, it is composed of a cylinder arranged in a fixed position and a piston that slides in the cylinder and is connected to a vertical moving body via a piston rod. A configuration in which the weight of the vertical moving body is supported by the pressure of the fluid is also known.

The applicant of the present application knows the following documents as the background art at the time of filing.
JP 11-077471 JP 2004-209550 A

  However, in a conventional machine tool, for example, when a vertical moving body is used as a headstock that supports a tool and the headstock is moved in a circular arc to perform an arc machining of a workpiece, the movable part of the counter balancer, When frictional resistance is generated at the seal part between the cylinder and piston or the seal part between the cylinder and piston rod, and the vertical movement is reversed in this state, in the vicinity of quadrant switching (in this case, the upper and lower sides) Due to the delay in the follow-up of the grindstone due to the frictional resistance, protrusions and depressions, so-called “quadrant protrusions” appear on the processed surface, causing poor processing accuracy (see FIG. 3A).

  More specifically, when the vertical moving body is reversed in direction by the feed driving means, the frictional resistance in the counter balancer is, for example, when the movement in the + direction is temporarily stopped and then the movement in the − direction is started. The frictional force (negative frictional force) that worked in the direction that hinders movement in the + direction suddenly changes to the direction that hinders movement in the-direction (positive frictional force). Since the feed driving means cannot follow the rapid change when the direction is reversed, it appears as a quadrant projection.

  FIG. 3 (B) shows the relationship between the driving force of the feed driving means in the movement of the vertical direction moving body and the command position. As shown by the broken line, the conventional one shows that when the moving direction is reversed, The driving force suddenly increases or decreases, and the rate at which this driving force changes is large, resulting in a follow-up delay and a quadrant protrusion.

  From these facts, in order to suppress quadrant projections, the counter balancer is designed to reduce the frictional resistance between the cylinder and the piston or piston rod. A structure in which the outer open end of the heavy cylindrical elastic sheet is fixed to the cylinder and the inner open end is fixed to the piston, and the seal between the cylinder and the piston is sealed and the sliding resistance is greatly suppressed, for example, a diaphragm In this case as well, sliding resistance remains between the cylinder and the piston rod, and a complicated seal structure is used, which increases the cost of the counter balancer and increases the cost. there were.

  Accordingly, the present invention has been made in view of the above-described situation, and in a machine tool having a vertical moving body that moves in the vertical direction, the counter balancer can follow up when the moving direction is reversed without significantly increasing the cost. An object of the present invention is to provide a machine tool capable of reducing the quadrant protrusion due to the delay and improving the machining accuracy.

  In order to solve the above-described problems, a machine tool according to the present invention includes a “vertical moving body that is movable in the vertical direction, a counter balancer for removing the influence of gravity on the vertical moving body, It comprises a buffer means disposed between the counter balancer and the vertical moving body.

  Here, the “vertical moving body” is not particularly limited, and examples thereof include a headstock for supporting a tool and a work support device for supporting a work. In addition, the “counter balancer” is not particularly limited, but examples include those that support weight by the pressure of fluid in the cylinder, and those that support weight by a balance weight movable in the vertical direction. Can do.

  The “buffering means” is not particularly limited, and examples thereof include rubbers, foams, springs, and other elastic bodies. In addition, as a spring, a leaf | plate spring, a disc spring, a coil spring, an air spring, etc. can be illustrated, These may be used individually or may be used in multiple numbers, or may be used in combination as appropriate.

  According to the present invention, the buffer means is provided between the vertical direction moving body and the counter balancer. Thus, when the movement of the vertical direction moving body is reversed, the friction resistance of the counter balancer is However, when the buffer means between the vertical direction moving body and the counter balancer is elastically deformed, the vertical direction moving body can move, and the follow-up delay is reduced. Quadrant projections can be suppressed, and processing accuracy can be improved.

  In addition, since quadrant projections can be suppressed, when trying to obtain the same processing accuracy, the processing speed can be increased, so that high-speed processing can be performed and processing efficiency can be increased. it can.

  Furthermore, it is possible to reduce the follow-up delay and suppress quadrant projections simply by providing a buffer means, so that it is not necessary to use a special cylinder or the like for the counter balancer, and it can be realized with a simple configuration and cost. Can be prevented from increasing.

  In addition to the above configuration, the machine tool according to the present invention may have a configuration in which “the counter balancer is driven by a fluid”. Here, the “fluid” may be liquid, gas, or the like, and oil, air, or the like may be exemplified as the fluid.

  According to the present invention, since the counter balancer is driven by a fluid, the entire machine tool can be reduced in size and cost can be reduced as compared with a counter balancer using a balance weight.

  In addition to the above configuration, the machine tool according to the present invention may have a configuration in which “the buffer means is made of a spring”.

  According to the present invention, the buffer means is a spring, which makes it possible to form a desired buffer means by an inexpensive method, which can suppress an increase in cost, as well as the material, elastic coefficient, etc. Therefore, it is possible to provide a buffer means according to the weight of the vertical moving body, the type of the machine tool, and the installation environment.

  As described above, according to the present invention, in a machine tool having a vertical moving body that moves in the vertical direction, without significantly increasing the cost, reducing the quadrant protrusion due to the counterbalancer's follow-up delay when the moving direction is reversed, A machine tool capable of increasing machining accuracy can be provided.

  Next, a machine tool which is the best embodiment according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a side view schematically showing a machine tool according to an embodiment of the present invention, and FIG. 2 (A) is an enlarged side view showing a main part of a counter balancer in the machine tool of FIG. (B) is a cross-sectional view of a single product showing an enlarged buffer means according to the present invention.

  The machine tool 10 of the present embodiment uses a grinding wheel as the tool T and controls the overall drive by a computer numerical control device (CNC), so that the workpiece W is axially symmetric with an error of several hundred nm to several tens of nm. It is an ultra-precision grinding machine that can be machined into shapes and free-form surfaces. As shown in FIG. 1, the X-axis movement guided in the X-axis direction (perpendicular to the paper surface) via the X-axis guiding means 12 on the upper surface of the bed 11 constituting the base portion of the machine tool 10. A body 13 is provided and is driven to move by the X-axis feed driving means 14.

  On the upper surface of the X-axis moving body 13, there is provided a Z-axis moving body 16 that is guided in the Z-axis direction (left-right direction in the figure) via the Z-axis guiding means 15. Is driven to move.

  The front surface (right side in the figure) of the Z-axis moving body 16 is provided with a work holding means 17 that holds the work W, and C that rotates the work W around the C-axis (Z-axis direction axis). A shaft rotation driving means 18 is provided so that the work W can be held and rotated around the C axis.

  Further, a Y-axis moving body 20 that is guided in the Y-axis direction (vertical direction) via the Y-axis guide means 19 is provided on the front side surface (right side surface in the figure) of the bed 11. It is driven to move by the feed drive means.

  The upper part of the Y-axis moving body 20 is provided with a headstock 22 that supports and rotates the tool T on a turning table 21 that can rotate around the B-axis (axis in the Y-axis direction). B-axis rotation driving means 23 for rotating the turning table 21 is provided, and the headstock 22 can be rotated around the B-axis via the turning table 21.

  In this example, the X-axis feed drive means 14, the Z-axis feed drive means, and the Y-axis feed drive means are each a linear motor, and each movable body and fixed body are configured to constitute a linear motor. A magnet and a coil are provided. This linear motor can be driven by energizing these coils, and can be fed with high accuracy with little play as compared with a ball screw.

  Below the Y-axis moving body 20, a counter for supporting the weight of the headstock 22, the turning table 21, the B-axis rotation driving means 23, and the Y-axis moving body 20 and reducing the load on the Y-axis feeding driving means. A balancer 24 is provided. The headstock 22, the turning table 21, the B-axis rotation driving means 23, and the Y-axis moving body 20 in this example correspond to the vertical direction moving body of the present invention.

  As shown in detail in FIG. 2A, the counter balancer 24 includes a cylinder 26 fixed to the bed 11 via a bracket 25 and a piston (not shown) whose base end is slidably disposed in the cylinder 26. A piston rod 27 that is fixed and extends upward from the cylinder 26 so as to be able to advance and retreat, a contact mechanism 28 that is disposed at the front end of the piston rod 27 and contacts the lower end of the Y-axis moving body 20, and It is comprised from the buffer means 29 arrange | positioned between the front-end | tips of the rod 27. FIG.

  The contact mechanism 28 includes a spherical contact member 30 that contacts the lower end of the Y-axis moving body 20 by point contact, a holding member 31 that holds the contact member 30, and a holding member 31 that is perpendicular to the axis of the piston rod 27. The slide mechanism 32 includes a plurality of spherical rolling members 33 and a holding plate 34 that holds the relative positions of the rolling members 33. .

  The abutment mechanism 28 is configured so that the displacement between the Y-axis moving body 20 and the counter balancer 24 due to dimensional tolerances of the cylinder 26, piston, piston rod 27, etc. of the counter balancer 24, mounting errors, etc. It does not affect the straightness.

  As shown in an enlarged view in FIG. 2B, the buffer means 29 includes an annular leg portion 35 and a lid portion 36 that closes the upper opening of the leg portion 35. The slide mechanism 32 of the contact mechanism 28 is placed and held. The lid portion 36 is a diaphragm spring having a predetermined thickness, and is elastically deformed when a load is applied from the Y-axis moving body 20 or the like via the slide mechanism 32, that is, the contact mechanism 28. It is like that.

  The counter balancer 24 supplies fluid such as air or oil at a predetermined pressure into the cylinder 26, so that the headstock 22, the turning table 21, the B-axis rotation driving means 23, and the Y-axis moving body 20 are generated by the pressure. It supports the weight. As a result, the Y-axis feed driving means is prevented from being loaded with weight, and the driving load is reduced.

  The counter balancer 24 moves the piston rod 27 forward and backward by supplying fluid to the cylinder 26 and causing the fluid to flow out in accordance with the movement of the Y-axis moving body 20 driven by the Y-axis feed driving means. The abutment mechanism 28 at the tip of the piston rod 27 is always brought into contact with the lower end portion of the Y-axis moving body 20 and supports its weight.

  Specifically, for example, when the Y-axis moving body 20 moves up, a fluid is supplied into the cylinder 26, and the piston rod 27 is advanced as the Y-axis moving body 20 moves up. Further, when the Y-axis moving body 20 is lowered, the fluid in the cylinder 26 is caused to flow out, and the piston rod 27 is moved backward together with the lowering of the Y-axis moving body 20 to support the weight.

  Next, the operation of the counter balancer 24 in the machine tool 10 of the present embodiment will be described in detail with reference to FIG. FIG. 3 is a diagram showing a comparison between the present invention and the prior art, (A) is a diagram showing a comparison of the amount of quadrant projections when processed into an arc shape, and (B) is a vertical moving body. It is a graph which compares and shows the relationship between the drive force of this feed drive means, and a command position.

  Here, in FIG. 3A, the upper direction in the Y-axis direction is defined as a positive direction, the lower direction is defined as a negative direction, the right direction in the figure is defined as a positive direction, and the left direction is defined as a negative direction. For example, when circular machining with a predetermined diameter is performed on the workpiece W, in the machine tool 10 of this example, the tool T is moved in the X-axis direction by moving the workpiece W in the X-axis direction by driving the X-axis feed driving means 14. By moving the feed driving means in the Y-axis direction and numerically controlling the feed amount and feed direction of the X-axis and Y-axis, circular machining with a predetermined diameter is performed.

  More specifically, first, the tool T supported on the headstock 22 is rotated at a predetermined speed, and then the X-axis feed driving means 14 is in the-direction and the Y-axis feed driving means is in the + direction, respectively. To process the arc shape from the leftmost quadrant to the upper quadrant in the figure. When the tool T reaches the upper quadrant, the Y-axis feed driving means is driven in the reverse direction to drive in the negative direction, and the arc shape from the upper quadrant to the right quadrant is machined.

  Subsequently, when the tool T reaches the right quadrant, the X-axis feed driving means is driven in the reverse direction and driven in the + direction to process an arc shape from the right quadrant to the lower quadrant. Then, when the tool T reaches the lower quadrant, the Y-axis feed driving means is driven in the reverse direction again to drive in the + direction, and a circular arc shape from the lower quadrant to the left quadrant is machined to obtain a predetermined Circular machining is completed.

  Incidentally, the Y-axis moving body 20 that moves in the Y-axis direction together with the tool T is supported by a counter balancer 24 for removing the influence of gravity. However, in the counter balancer 24, a cylinder 26, a piston, and a piston rod 27 are used. There are various frictional resistances, and in the vicinity of switching between the upper and lower quadrants, when the feed direction in the Y-axis direction is reversed, the Y-axis moving body 20 is compared with the feed of the Y-axis feed driving means. There is a delay in movement, which appears as quadrant projections on the machined surface.

  This movement will be described in detail. In the vicinity of quadrant switching, for example, even if the feed direction of the Y-axis feed driving means is reversed from the + direction to the-direction and the Y-axis moving body 20 is about to descend, the counter balancer 24 The piston rod 27 does not start to be retracted into the cylinder 26 until the force to overcome the frictional force change caused by the direction reversal is applied, but in this example, the piston rod 27 and the Y axis Since the buffer means 29 is provided between the movable body 20 and the buffer means 29, the Y-axis mobile body 20 can be lowered by elastic deformation of the buffer means 29, while the buffer means 29 is elastically deformed. In the counter balancer 24, a force that overcomes the frictional force is applied, the piston rod 27 starts to retract, the follow-up delay of the Y-axis moving body 20 is alleviated, and the quadrant protrusion is suppressed.

  FIG. 3 (A) is an enlarged view of the upper quadrant projection by the above processing, and as shown by the solid line in the figure, the present example is compared with the conventional one shown by the broken line, The height of the quadrant protrusion is as low as 30 to 40%, and the effect of the buffer means 29 can be seen. Furthermore, the height of the quadrant projection can be lowered by designing the spring constant of the buffer means 29 to be smaller.

  Further, as shown in FIG. 3B, the change in the driving force of the Y-axis feed driving means when the feed direction is reversed is a gradual change compared to the conventional one. It can be seen that such a load is also suppressed.

  Thus, according to the machine tool 10 of this embodiment, since the buffering means 29 is provided between the Y-axis moving body 20 and the counter balancer 24, when the feed direction of the Y-axis moving body 20 is reversed. Since the buffer means 29 is elastically deformed, the Y-axis moving body 20 can move, the follow-up delay can be reduced, quadrant projections can be suppressed, and the processing accuracy can be improved.

  In addition, since quadrant projections can be suppressed, when trying to obtain the same processing accuracy, the processing speed can be further increased, so that high-speed processing can be performed, and the processing efficiency of the high-speed machine 10 Can be increased.

  Furthermore, since the counter balancer 24 is driven by a fluid, the entire machine tool 10 can be reduced in size and cost can be reduced as compared with a counter balancer using a balance weight. .

  Further, since the buffer means 29 is a spring, the desired buffer means 29 can be formed by an inexpensive method, and an increase in cost can be suppressed.

  The best embodiment for carrying out the present invention has been described above, but the present invention is not limited to this embodiment, and the scope of the present invention is not deviated from the following, as shown below. Various improvements and design changes are possible.

  That is, in the machine tool 10 of the present embodiment, the buffer unit 29 is integrated with a member that holds the slide mechanism 32 of the abutment mechanism 28, and the diaphragm type spring is shown. However, the present invention is limited to this. For example, the configuration shown in FIG. 4 may be used. 4 (A) is a combination of a plurality of disc springs, and the buffer means 41 of FIG. 4 (B) is composed of a plurality of coil springs arranged at predetermined intervals in the circumferential direction. The buffer means 42 in FIG. 5C is made of an elastic container made of rubber or the like, and the buffer means 43 in FIG. 4D is made of an elastic body such as rubber or foamed resin. . The buffer means 44 shown in FIG. 5E is made of an elastic ring as shown. These can also provide the same effects as described above.

  Moreover, although the ultra-precision grinding machine was shown as the machine tool 10 of this embodiment, it is not limited to this, If it is provided with the vertical direction moving body, a milling machine, a grinding machine, a lathe, a machining center, etc. It can be set as the machine tool of another form, and there can exist an effect similar to the above.

1 is a side view schematically showing a machine tool according to an embodiment of the present invention. (A) is an expanded side view which shows the principal part of the counter balancer in the machine tool of FIG. 1 in a cross section, and (B) is a single product cross-sectional view which expands and shows the buffer means according to the present invention. It is a figure which compares and shows the Example of this invention, and the prior art, (A) is a figure which compares and shows the quantity of the quadrant protrusion when processed into circular arc shape, (B) is a figure of a vertical direction moving body. It is a graph which compares and shows the relationship between the drive force of a feed drive means, and a command position. (A)-(D) are figures which show the buffer means of a form different from the example of FIG.

Explanation of symbols

10 Machine tool 20 Y-axis moving body (vertical moving body)
21 Turning table (vertical moving body)
22 Headstock (vertical moving body)
23 B axis rotation drive means (vertical moving body)
24 Counter balancer 29 Buffer means 40 Buffer means 41 Buffer means 42 Buffer means 43 Buffer means 44 Buffer means

Claims (3)

A vertical moving body movable in the vertical direction;
A counter balancer for removing the influence of gravity on the vertical moving body;
A machine tool comprising shock absorbing means disposed between the counter balancer and the vertical moving body. The counter balancer is
The machine tool according to claim 1, wherein the machine tool is driven by a fluid. The buffer means is
The machine tool according to claim 1, wherein the machine tool is made of a spring.

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