JPH06339827A - Rotary table of machine tool - Google Patents

Abstract

PURPOSE:To provide a modified mechanical structure which can improve the mechanical rigidity of a rotary table in a machine tool and promote smooth rotation. CONSTITUTION:To A rotary table 10 which is mounted onto a bed 8 through a table base 12, and is provided with a rotary base 20 supported so as to rotate around a vertical axis through a rotating bearing 18 is formed with a lower sliding surface 20a and an upper sliding surface 20b which face each other at the upper and lower parts, where the upper sliding surface 20b is constituted so as to be pressed by an outer pressing plate 24. By bringing the rotary base 20 into sliding contact, with the table base 12 and the pressing plate 24 and clamping it, the rotary table is restrained from rising up in the vertical axis direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary table for a machine tool, and more particularly, it is improved so as to exhibit a high degree of mechanical rigidity with respect to a cutting force acting through the work during cutting of the work and a moment due to lifting. The present invention relates to a rotary table of a machine tool that has an improved structure and is therefore capable of improving cutting ability such as cutting speed and cutting amount.

[0002]

2. Description of the Related Art A rotary table of a machine tool has a structure in which a work is mounted and is rotatably supported around a predetermined rotation axis from a minute amount of indexing rotation to a large rotation angle for positioning in the rotation direction. Is equipped with. That is, a rotary table of a conventional machine tool is usually vertically mounted via a radial rotary bearing and a thrust rotary bearing held by a bearing holder provided in a table base capable of linear sliding on a bed of the machine tool. It is rotatably supported around an axis and has a structure in which a rotational driving force supplied from a drive source motor is rotated via a transmission mechanism such as a gear mechanism or a belt / pulley mechanism. In particular, the numerically controlled NC rotary table is provided with a rotation detector that detects the amount of table rotation, and has a structure in which precise table rotation control is performed in accordance with feedback from this rotation detector.

[0003]

As described above, the rotary table of the conventional machine tool as described above is provided with the radial rotary bearing and the thrust rotary bearing to support not only the radial load but also the thrust load. Although it has a structure, during the cutting action, due to the cutting force acting on the rotary table through the work, etc., a moment with the distance from the center of rotation as the arm length acts on the rotary table. Since the thrust bearing cannot be sufficiently supported, the rotary table may exhibit a phenomenon of lifting in the vertical axis direction.

Further, since the above-mentioned radial bearings and thrust bearings that rotatably support the rotary table are arranged in a column in the axial direction, the mechanical size of the rotary table inevitably increases in the axial direction. Mechanical rigidity is reduced. Therefore, it is difficult to mount and process a heavy work piece, and
In some cases, it may not have sufficient resistance to a large cutting load such as heavy cutting or high speed cutting.

Therefore, an object of the present invention is to solve the structural problem of such a conventional rotary table and to withstand a large cutting load acting through a workpiece during cutting of a machine tool. The present invention provides a rotary table having a structure with mechanical rigidity capable of

[0006]

In view of the above-mentioned object, the present invention is mounted on a bed of a machine tool via a table base and is rotatable on the table base around a vertical axis via a bearing means. On a rotary table having a supported turntable, a lower sliding surface formed between the table base and an upper region vertically opposed to the lower sliding surface is pressed from above by an external pressing plate. A sliding surface is formed, and the rotary base is slidably contacted and clamped by the table base and the pressing plate via the sliding surfaces facing each other vertically, thereby suppressing lifting of the rotary table in the vertical axis direction, In addition, the rotary table of the machine tool has a structure having improved mechanical rigidity.

That is, according to the present invention, the rotary table mounted on the bed of the machine tool via the table base and rotatably supported about the vertical axis, and the work integrally provided on the rotary table. In a rotary table of a machine tool having a mounting table portion or a pallet portion, the rotary table has a lower sliding surface that forms a sliding portion with the table base on at least a part of a lower surface of the rotary table. An upper sliding surface facing the lower sliding surface is provided on a part of the upper surface of the rotary table,
Provided is a rotary table for a machine tool, which is provided with a sliding contact surface that comes into sliding contact with an upper sliding surface of the rotary table from above, is fixed at a predetermined stationary position, and is provided with a holding plate for suppressing upward displacement of the rotary table. Of.

[0008]

In the rotary table of the machine tool of the present invention having the above-described structure, the lower slide surface portion between the table base and the upper slide surface portion between the holding plate ensures smooth rotation of the rotary table. At the same time, it supports the thrust load in the vertical axis direction, and because the sliding bearing structure part with high mechanical rigidity is formed to slide and contact so as to suppress the lifting of the rotary table, the work is mounted and the cutting process is performed. When performing, it is possible to exert a large durability against the cutting force and moment acting on the rotary table through the work, and it is possible to improve the cutting ability of the machine tool.

The present invention will be described below in more detail based on the embodiments shown in the accompanying drawings.

[0010]

1 is a sectional view and a fluid control circuit diagram showing an embodiment of a rotary table of a machine tool according to the present invention. In FIG. 1, a machine tool has a bed 8 forming a base element thereof, a column (not shown) is erected on a part of the bed 8, and a spindle head that can move up and down is provided in the column. A spindle holding a cutting tool is mounted.

A rotary table 10 on which a workpiece machined by a tool held by the spindle is mounted is provided on another part of the bed 8, and the rotary table 10 has a table base 12 interposed therebetween. The beds 8 are provided in a stacked arrangement structure. The table base 12 is arranged in a predetermined linear direction with respect to the upper surface 8a of the bed 8, for example, as shown in FIG.
Is slidably arranged in the direction of the X-axis perpendicular to the paper surface of the table, and the sliding contact portion between the upper surface 8a of the bed 8 and the lower surface 12a of the table base 12 has a slippery synthetic resin material, for example, A sliding guide layer 14 made of a well-known tetrafluoroethylene material or the like is provided by being attached to some of the upper and lower surfaces forming the sliding contact portion.

A cylindrical bearing holding portion 16 is formed at an appropriate portion of the table base 12, and the rotary table 10 is rotatably mounted via a rotary bearing (radial bearing) 18 held by the bearing holding portion 16. Is supported. The turntable 10 has a lower portion formed as a turntable 20,
The rotary table 20 serves as the bearing holder 1 of the table base 12.
6 is rotatably supported by a rotary bearing 18. A table portion 22 integrally formed with the rotary table 20 or integrally connected to the rotary table 20 by a connecting means such as a bolt screw is provided at the upper part of the rotary table 20. A rotary table 10 that is rotatable around the vertical axis is formed by the combined body. In the illustrated example, the rotary table portion 22 having a T-groove is shown for convenience, but the table portion 22 is replaced with a pallet provided with work clamp means as required, and the rotary table 20 is mounted on the rotary table 20. Alternatively, the pallet may be detachably attached.

The rotary table 20 of the rotary table 10 is
The bearing holder 16 described above is formed perpendicularly to the vertical axis formed on the table base 12 with a relatively large area.
Sliding contact with the upper surface 12b formed as an annular region around the
The lower surface 20a of the turntable 20 that is supported forms a sliding portion that slides along the upper surface 12b of the table base 12 during rotation. Then, in this sliding portion, the upper surface 12b of the table base 12 or the lower surface 2 of the turntable 20 is used.
0a, a slide guide layer 14 similar to the slide guide layer 14 made of a synthetic resin material having lubricity such as the above-mentioned tetrafluoroethylene material is adhered and inserted, and the rotary base 20 of the table base 12 is attached. It plays the role of smoothly guiding the sliding rotation.

On the other hand, a part of the upper region of the rotary table 20, in particular, a planar annular surface 20 axially opposed to the lower surface 20a.
b is formed. The annular surface 20b is preferably in sliding contact with the holding surface 24a of the holding plate 24 fixed to the table base 12 or to the external stationary portion of the machine as required, and the annular surface 20b and the holding plate 24 are connected to each other. Pressing surface 24
A sliding guide layer 14 made of the above-mentioned slippery synthetic resin material is also adhered and interposed on the sliding contact surface portion with a so as to smoothly guide the sliding action on both surfaces.

As is apparent from the above, the rotary table 1
The rotary table 20 of 0 is provided so as to be slidably sandwiched between the table base 12 and the holding plate 24. The upper surface 12b of the table base 12 and the holding surface 2 of the holding plate 24 are provided.
4a forms a slide bearing portion having a slide guide layer 14 with respect to the rotary table 20, and rotates the rotary table 20, and thus the rotary table 10 smoothly without rattling together with the rotary bearing 18 of the radial bearing type. Have a configuration. Moreover, the turntable 2
Since 0 has a structure in which it is pressed from above by the pressing plate 24 via its annular surface 20b, for example, when the work W mounted and mounted on the table portion 22 is cut, the work W, Even when a cutting force acts on the rotary table 20 through the table portion 22 or a moment due to the acting force acts on the rotary table 20, the rotary table 20 does not lift like the conventional rotary table. is there. That is, it can function as a rotary table and a rotary table with sufficiently large mechanical rigidity, and therefore can exhibit sufficient mechanical resistance to a large cutting force and high-speed cutting, and also has a rotary table. Since there is no backlash, it is possible to guarantee a sufficiently high processing accuracy.

The rotary table 20 of the rotary table 10 is
It has a structure of rotating by receiving a rotation driving force from the outside, and for example, rotation transmitted from the drive motor 30 through the gear train 32 to the driven teeth 36 formed on the outer peripheral portion of the rotary table 20 as illustrated. It is configured to rotate about the center of the rotary bearing 18, that is, the vertical axis, by the driving force. In addition,
If necessary, the rotation table 20 may be provided with a rotation detector 38, and the drive motor 30 may be controlled according to the detected force of the rotation detector 38. If the detected force is fed back to, for example, a numerical control device (NC device) and the drive motor 30 is driven by the NC device, the rotary table 10 can be formed as an NC control rotary table.

The structure of the rotary table 10 shown in the above has the structure for restraining the lifting by the pressing plate 24 described above, and further, the upper surface 12b of the table base 12 is further provided.
A pressure fluid, generally pressure air having a predetermined pressure, is supplied to a sliding portion formed between the rotary table 20 and the lower surface 20a of the turntable 20 to constantly form an air layer having a predetermined thickness. The rotary table 20, that is, the rotary table 10, has a configuration for further improving smoothing of the rotating action.

That is, a plurality of air pockets or pads 40 are spaced from each other on the lower surface 20a of the rotary table 20 at appropriate intervals, and the pads 40 have pressure air sources 44 to pressure control valves of a pressure control system 50. Pressure air having a predetermined pressure supplied via 52 is supplied, and this pressure air forms a pressure air layer in the sliding portion. Therefore, the turntable 20,
That is, the rotary table 10 is in a state of being lifted upward with respect to the table base 12 by the air layer thickness due to the static pressure of the air layer. Therefore, the table base 12
The sliding resistance between the upper surface 12b and the upper surface 12b is further reduced in addition to the reduction by the sliding guide layer 14, and the smoothing of the rotating operation of the rotary table 10 is promoted. is there.

The pressure control system 50 includes a pressure air source 44.
Is formed as an air pressure control system including the pressure control valve 52, the pressure reducing valve 68, the check valve 70, the pressure system 72, etc. The control valve 52 has a configuration in which it is supplied from the supply port 58 of the control valve 52 to the air pad 40 through the pipe 54, and the static pressure of the pressure air layer is detected by the pressure detection pad 42 arranged in parallel with the pad 40, This detection value is fed back from the detection pipe 56 to the pressure control valve 52 to set and maintain the amount of pressure air supplied through the pressure control valve 50 at a predetermined level.

The pressure control valve 52 communicates with the pressure air source 44 through the pipe line 46, is supplied with pressure air to the inlet port 60, and the direct-acting spool 62 provided therein has an opening degree of the inlet port 60. Is controlled, and the pressure air supply amount is controlled according to the opening degree. The spool 62 is connected to a diaphragm 64 arranged between the opposing pressure chambers 66a and 66b formed at the end of the pressure control valve 52, and the diaphragm 64 follows the pressure difference between the pressure chambers 66a and 66b. The spool 62 has a structure in which the spool 62 is axially moved according to the displacement, and the opening amount of the inlet port 60 is controlled by the taper portion 62a of the spool 62. The pressure chamber 66b described above communicates with the detected pressure portion of the pressure detection pad 42 via the conduit 56, and the pressure chamber 66a communicates with the air pressure source 44 via the pressure reducing valve 68. The pressure reducing valve 68 sets the pressure level of the predetermined pressure air to a predetermined value, and the pressure level of the pressure chamber 66a to which the pressure air is supplied via the pressure reducing valve 68 and the pressure chamber 66b via the conduit 56.
The spool 62 is linearly displaced according to the difference value between the detected pressure of the pressure air fed back to and the opening degree of the inlet port 60 is controlled as described above.

As described above, by the air supply circuit having the pressure control system 50, the pressure air is supplied to the pad 40 on the rotary sliding surface between the table base 12 and the rotary table 20 to act on the rotary table 10. It is possible to reduce and maintain the contact frictional force on the rotary sliding surface to a predetermined value irrespective of the fluctuation of the axial load. Regarding this so-called semi-floating guide type load compensating guide surface, Japanese Patent Publication No.
It is described in detail in JP-A No. 1-32525 and JP-B No. 61-16575, so further description will be omitted in this description.

As described above, in the rotary table 10 according to the preferred embodiment of the present invention, the thrust bearing action and the pushing action from above are mainly composed of the retainer plate 24 and the table base 12 acting on the rotary table 20. Or to form a rotating structure with high mechanical rigidity by receiving the lifting suppression effect,
In addition, since the rotating structure with high rotation accuracy is formed by the smooth rotation promotion effect of the above-mentioned semi-floating guide method, it is possible to perform heavy cutting and high-speed cutting with a large cutting value when cutting a workpiece with a machine tool. Moreover, it is possible to improve the cutting accuracy.

[0023]

As is apparent from the above description, according to the present invention, firstly, it is mounted on a bed of a machine tool via a table base, and the table base is provided with bearing means to rotate around the vertical axis. A rotary table having a turntable rotatably supported on a lower slide surface formed between the table base and the upper base vertically opposed to the lower slide surface by an external presser plate from above. The upper slide surface that is held down is formed, and the rotary table is lifted up in the vertical axis direction by sliding and sandwiching the rotary base between the table base and the retainer plate through the upper and lower opposite slide surfaces. Since the rotary table of the machine tool has a structure that suppresses the above and improves the mechanical rigidity, it improves the cutting ability to enable heavy cutting and high-speed cutting when cutting a workpiece with a processing tool. The figure It is possible. Secondly, by applying a resin lubrication layer or a semi-floating guide system to the sliding area of the rotary base of the rotary table, the smoothness of rotation is further enhanced,
In addition, since it enables high-precision rotation control, high-precision rotation indexing control can be performed, for example, when cutting is automatically performed on a workpiece mounted and installed on a rotary table by the rotary indexing control method. As a result, it is possible to obtain the effect that it is possible to ensure high processing accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view and a fluid control circuit diagram showing an embodiment of a rotary table of a machine tool according to the present invention.

[Explanation of symbols]

 8 ... Bed 10 ... Rotating table 12 ... Table base 12a ... Lower surface 12b ... Upper surface 14 ... Sliding guide layer 20 ... Rotating table 20a ... Lower surface 20b ... Upper surface 22 ... Table part 24 ... Press plate 50 ... Pressure control system 52 ... Pressure control valve

Claims (2)

[Claims] 1. A rotary table mounted on a bed of a machine tool via a table base and rotatably supported about a vertical axis, and a work mounting table section or pallet integrally provided on the rotary table. And a lower slide surface that forms a sliding portion between the rotary base and the table base, and the upper surface of the rotary base. An upper slide surface facing the lower slide surface is provided in a part of the rotary slide table, and a slide contact surface that comes into sliding contact with the upper slide surface of the rotary table from above is provided, and the slide table is fixed at a predetermined stationary position. A rotary table for a machine tool, which is provided with a holding plate for suppressing upward displacement. 2. An upper surface of the table base or the rotary table so that a jet of air having a predetermined pressure can be supplied to a sliding portion formed between the table base and a lower sliding surface of the rotary table. A pocket is provided on the lower sliding surface of the pocket, and a pressure control means is provided in the air supply circuit of the pocket so that the contact frictional force of the sliding portion can be reduced to and maintained at a predetermined value by the air jet flow regardless of fluctuations in load. The rotary table for a machine tool according to claim 1, wherein the rotary table is provided.