JPS5926814B2 - damper device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a high-precision table feeding device using a ball screw or the like for machine tools, measuring instruments, etc., and in particular uses the squeeze film effect of viscous fluid to reduce static accuracy. The present invention relates to a table feeding device equipped with a damper device for improving dynamic rigidity without causing any damage.

In general, machine tools that perform high-precision cutting operations and tables of measuring instruments that measure the dimensions of objects to be measured are moved by feed screw means that utilizes a rotary motion-to-linear motion conversion mechanism using a screw mechanism.

It is desirable that the sliding resistance of the guide surface used in this table or the like is small, and for this reason, hydrostatic bearings or rolling guides are often used. Furthermore, in order to reduce friction and wear and improve conversion efficiency, the conversion mechanism employs a static pressure screw using static pressure fluid, a ball screw using rolling balls, and the like. As a result, static accuracy has improved and high-precision feeding has become possible, but a decrease in dynamic rigidity is unavoidable, resulting in new problems such as the occurrence of chatter vibrations.

The present invention was developed in view of the above-mentioned problems. In order to ensure static accuracy, a static pressure screw, a ball screw, and a rolling guide are used. The purpose is to provide a table feeding device loaded with a damper element to ensure rigidity, and in particular, to provide a table feeding device with a damper element to ensure rigidity. The purpose is to develop a damper device that exhibits the following effects and to provide a table feeding device that incorporates the damper device.

Figures 1 and 2 show an example of a damper device in the sliding direction that is commonly used on tables of machine tools and the like.

This is caused by the radial gap between the piston 1 and cylinder 2 that move relative to each other together with the table 5, or by the viscous resistance of the fluid 3 flowing through the axially drilled hole 4 of the piston 1.
A damping effect is obtained. However, this type of conventional viscous damper has the following problems. (a) The cylinder 2 must be filled with fluid (incompressible) 3.

If a compressible fluid such as air (e.g. bubbles) is mixed especially in the right chamber of cylinder 2, a strong Danhisog effect will be especially noticeable. (B) One end of cylinder 2 must be a rigid body. must be closed.

That is, it is generally difficult to adopt the structure shown in FIG. 2 because of the insufficient rigidity of the seal portion of the piston rod (or leakage from the seal portion). Therefore, as shown in FIG. 1, one end of the cylinder 2 must be opened and an oil reservoir must be installed to adjust the flow of oil as the table 5 slides. When trying to move the Hira table 5 rapidly (for example, when moving a table of a machine tool without load), a very large driving force is required due to the resistance of the damper.

In view of the above-mentioned drawbacks of conventional damper devices, the damper device incorporated in the table feeding device of the present invention is designed to move relatively, such as between an immovable bed (or an axially immovable screw shaft) and the table of a machine tool. When the table is statically moving, it does not provide any resistance, and only exerts its damper function when dynamic vibrational load changes are applied. As mentioned above, in order to utilize the squeeze film effect caused by the oil film,
A helical protrusion for a damper, which is the same as the lead pitch of the nut member screwed with the feed screw shaft member, is provided on a part of the feed screw shaft member of the feed screw means of the table, and this helical protrusion is oriented in the axial direction. A hollow outer member having a spiral groove on the inner periphery that is the same as the lead pitch of the nut member surrounding it with a uniform predetermined gap is fixed to the table side, and a spiral protrusion is positioned within the spiral groove. A first damper device is constructed by sealing viscous oil in a sealed chamber formed when the damper is used, and a feed screw shaft is provided as necessary to further enhance the damper effect. It consists of a second damper device.

Hereinafter, the structure of the table feeding device according to the present invention incorporating the above-mentioned damper device will be described with reference to the embodiments shown in FIGS. 3 to 6. In addition, the example is
FIG. 3 shows a case where the first and second damper devices according to the present invention are combined, and a workpiece is mounted on a table and processed with a tool.

In the figure, 11 is a table, 12 is a workpiece on the table, 13 is a crown tool for machining the workpiece 12, 14 is a ball slide, and 15 is a nut member fixed to the table 11 side that meshes with the feed screw shaft. It is. The table 11 is supported and guided by a rolling ball slide 14 for sliding motion. The drive of the table 11 is
This is performed by a feed screw shaft portion (ball screw, static pressure screw, etc.) 16 of a shaft member supported by a pair of bearings 17, 17. A shaft member having the feed screw shaft portion 16 as a part thereof is rotated by a drive source 19 such as a pulse motor via a reduction gear device 18 or the like. The symbol attached to the crop 12 in the drawing indicates the component of the applied force in the sliding direction, and normally when the damping of this system is small, a large vibration component is included. The present invention provides a first damper device C described below.
The first and second damper devices C2 are intended to reduce and eliminate the above-mentioned vibration components. The first damper device C1 includes a feed screw shaft portion 16 and a rod portion 20 having a spiral protrusion portion 21 having the same lead pitch as the feed screw shaft portion 16, and A shaft member rotatably supported on the bed 27 and a spiral groove having the same lead pitch as the spiral projection 21 are provided on the inner periphery so as to surround the spiral projection 21, It also includes a hollow outer member 22 fixed to the table 11. 23 is a highly viscous rod sealed in a sealed chamber formed by the spiral protrusion 21, the hollow outer member 22, and the seal members 31 and 32 provided between the hollow outer member 22 and the rod portion 20; , a highly incompressible fluid such as silicone oil.

Since the silicone oil used in the present invention is like starch syrup, the silicone oil in the gap between the spiral protrusion 21 and the groove adheres to the surfaces of the protrusion and the groove, so that the protrusion is When it rotates, the silicone oil is sheared at the intermediate surface of the gap, and especially the silicone oil on the protrusion side sticks to the protrusion and moves. Further, the hollow outer member 22 has a bypass passage 22'' for oil movement inside. By the way, since the spiral protrusion 21, the feed screw shaft 16, and the spiral groove have the same lead pitch, the spiral The rotation of the shaped protrusion 21 and the movement of the hollow outer member 22 are at the same timing,
As a result, the spiral protrusion 21 and the groove move relative to each other while maintaining a uniform clearance. The bypass passage 227 of the hollow outer member 22 allows the viscous oil in the groove on the side where the protrusion invades to flow into the groove on the other side when the helical protrusion moves relatively within the helical groove. This is a passage for moving the table, and this bypass passage allows the screw feeding means to smoothly feed the table. The second damper device C2 is disposed on the open end side of the rod portion 20 of the shaft member, and includes a large diameter portion 24 that enlarges the end of the rod portion 20, and a large diameter portion 24 that surrounds this large diameter portion 24 and is provided on the bed 27 side. A fixed cylinder member 25, a seal member 33 disposed between the rod portion 20 and the cylinder member 25, and a highly viscous seal sealed between these, and
It is made of highly incompressible fluid, such as high viscosity silicone oil 26. The gap between the spiral protrusion 21 and the spiral groove of the hollow outer member 22, and the outer surface of the enlarged large diameter portion 24 at the end of the rod portion 20 and the cylinder member 25.
A predetermined gap is maintained between the inner wall surfaces of the cylinder member 25, particularly between the end surface of the large diameter portion 24 of the rod portion 20 and the inner end wall surface of the cylinder member 25, so that they are always in contact with each other through an oil film. is set to r1, 1 day+.
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Arm Lk...Evening squeeze film effect. In the above description, the rod member 20 constituting the second damper device C2
Although a case has been described in which the end portion of the rod member 20 is enlarged to form a large diameter portion, the end portion of the rod member 20 is not formed with a large diameter portion, but the end face of the rod member is opposed to the inner wall surface of the cylinder, and a predetermined gap is formed between the two. If such a gap is formed, a sufficient squeeze film effect can be expected, and a sufficient desired damping effect can be obtained. That is, taking the first damper device C1 as an example,
When the gap between the helical groove and the helical protrusion changes relatively and rapidly, a reaction force proportional to the rate of change is generated by the oil film. The second damper device C2 is also based on exactly the same principle. Since the present invention has the above structure, the vibration component of the load applied to the table is transmitted to the first damper device C1, that is, the intermediate outer member 22 provided on the table and the spiral protrusion 21 provided on a part of the rod portion. The vibration component of the load applied to the bed as a whole is absorbed between the second damper device C2, that is, the cylinder member 25 provided on the bed and the end face of the rod portion.

The meshing part between the feed screw shaft part 16 and the nut member 15 and the support part of the feed screw shaft part are each regarded as spring elements, and the spring constants are denoted by symbols Kl and K2, and the system in FIG. 3 is extremely simplified. Figure 4 shows a typical model.

However, the symbol M1 is the mass of the table, and M2 is the mass of the feed screw system, and generally M1>M2. As reference,
An example (calculation result) showing the effect of the damper of the table feeding device in the present invention is described below.

Considering the system of the above specifications, the viscosity is 1.15X10-8kg・
FIG. 6 shows the frequency response curve when using SeC/M77l viscous oil.

From this figure, it can be seen that by adding the first and second damper devices Cl and C2, a significant improvement in the dynamic rigidity of the entire table feeding device is expected. In addition, in FIG. 6, the excitation frequency is the frequency of vibration generated during machining, for example, the excitation force is the force that generates vibration during machining, and the displacement response amplitude is, for example, the frequency of vibration generated during machining. This is the amplitude of vibration generated in the table relative to the bed when the second damper devices Cl, C2 are added or not.

As explained above, the present invention provides a table that slides on an immovable bed, a nut member for a feed screw means, a helical groove on the inner periphery that is the same as the lead pitch of the nut member, and both ends of the groove. Hollow outer members for the damper means forming a bypass passage to be connected are arranged side by side with their axes aligned, and a feed screw shaft portion screwed with the nut member and a spiral groove of the hollow outer member are arranged in parallel. A shaft member having a rod part having a spiral protrusion in a part thereof is rotatably provided on the bed, and a shaft member is provided between the spiral groove of the hollow outer member and the spiral protrusion of the shaft member. A continuous spiral uniform gap is formed, a sealing member is used to form a sealed chamber between the hollow outer member and the rod, viscous oil is sealed in the sealed chamber, and the end of the rod is sealed. The rod is inserted into a cylinder member fixed to the bed, and a predetermined gap is formed between the end face of the rod part and the inner wall face of the cylinder member facing the end face, and a seal member is used between the rod part and the cylinder member. Since it is a sealed chamber and viscous oil is sealed in this sealed chamber,
Various effects described below can be expected.

In other words, damping is obtained by the squeeze film effect of the oil film that is viscous and moves while adhering to the spiral protrusion, so even if a certain amount of air bubbles are present in the viscous oil in the damper device, the damping is sufficient. The effect (damper characteristics against dynamic load fluctuations) can be improved significantly, and maintenance of the table feeding device can be simplified. Alternatively, viscous oil is simply sealed inside the damper device, and both ends are sealed using oil seals or the like.
Since it can be configured by simply inserting it into the table, it is easy to assemble the table feeding device, and the overall structure can be simple and compact, and it can also be used for rapid movement of the table (fast forwarding, fast reversing, etc.). As long as it is static, viscous oil does not produce any acting force (resistance force), so it does not increase sliding resistance and also reduces the high conversion efficiency of ball screws etc. There is no.

The capacity of the input table drive source (pulse motor, hydraulic actuator, etc.) can be reduced. Furthermore, by providing the bypass passage, the damper means does not become a resistance to table feeding by the screw feeding means, and chatter vibrations and the like can be reliably absorbed by the damper means.

[Brief explanation of drawings]

1 and 2 are drawings for explaining a conventional damper device. FIG. 3 is a diagram showing the table feeding device of the present invention. FIG. 4 is a diagram showing a mechanical model of the table feeding device shown in FIG. 3. Figures 5a and 5b show the first damper device C1 and the second damper device C, respectively.
2 is a drawing for explaining 2. Figure 6 shows the first and second
FIG. 3 is a drawing showing frequency response curves when the damper devices Cl and C2 are used in the table feeding device and when they are not used. 11...Table, 14...Ball slide, 15...Nut member, 16...
...Feed screw shaft, 17, 17...Bearing, 18...Deceleration device, 19...Drive source such as pulse motor, C1... First damper device, 22... Hollow outer member, 21...
・Spiral-shaped protrusion, 27...Bypass passage, 2
3...Viscous oil, C,...Second damper device, 24...End of rod part, 25...
... Cylinder member, 26 ... Viscous oil, 27.
...Bed, 31, 32, 33... Seal member.

Claims (1)

[Scope of Claims] 1. A nut member for a feed screw means, a spiral groove having the same lead pitch as the nut member on the inner periphery, and both ends of the groove are connected to a table that slides on an immovable bed. Hollow outer members for the damper means forming a bypass passage are arranged side by side with their axes aligned, and the feed screw shaft portion threadedly engaged with the nut member is positioned within the spiral groove of the hollow outer member. A shaft member equipped with a rod portion having a helical protrusion in part thereof is rotatably provided on the bed, and a continuous groove is provided between the helical groove of the hollow outer member and the helical protrusion of the shaft member. A table feed for a machine tool or the like, characterized in that a uniform spiral gap is formed, a sealing member is used to form a sealed chamber between the hollow outer member and the rod part, and viscous oil is filled in the sealed chamber. Device. 2. A nut member for the feed screw means and a spiral groove having the same lead pitch as the nut member and a bypass passage connecting both ends of the groove are formed on the inner periphery of a table that slides on an immovable bed. Hollow outer members for damper means are arranged side by side with their axes aligned, a feed screw shaft portion that is threadedly engaged with the nut member, and a helical protrusion located within the helical groove of the hollow outer member. A shaft member having a rod portion having a part thereof is rotatably provided on the bed, and a continuous spiral uniform groove is provided between the spiral groove of the hollow outer member and the spiral protrusion of the shaft member. A cylinder member forming a gap, forming a sealed chamber between the hollow outer member and the rod part with a sealing member, sealing viscous oil in the sealed chamber, and further fixing an end of the rod part to the bed. A predetermined gap is formed between the end face of the rod part and the inner wall face of the cylinder member facing the end face, and a sealing member is used to form a sealed chamber between the rod part and the cylinder member. A table feeding device for machine tools, etc., characterized by a sealed chamber filled with viscous oil.