JPS6243723Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a spindle head for a machine tool that incorporates an eccentric mechanism and an axial oscillation mechanism.

Traditionally, cams were processed to the finished dimensions using only cutting, and no special machining was performed after hardening, but in recent years, as demand for cams has increased, precision has improved and the cam contact surface has become rougher. There has been a strong demand for improvement in quality. With this trend, special machines equipped with grinding heads and air-driven grinding attachments are being used to grind cams.

However, in the case of a dedicated machine with a grinding head, it can only be applied to cams with a simple shape or cams with a fixed shape, and this poses a problem in terms of production efficiency. Furthermore, these dedicated grinding head machines do not have a built-in mechanism for oscillating the grinding wheel in the axial direction, which causes problems such as the formation of grinding marks on the finished surface. In addition, in the case of air-driven grinding attachments that are generally available on the market, since the turbine is rotated by air pressure, the grinding capacity is low and the grinding wheel cannot grind to the required size, and axial direction oscillation is not possible due to the mechanism. It was hot.

Therefore, our idea was to incorporate a grindstone spindle with a mechanism that can set the eccentricity relative to the main spindle and an axial oscillation mechanism into the main spindle of an NC milling machine so that it can be easily attached and removed. The above-mentioned drawbacks of the conventional device have been improved and eliminated by driving the device using an AC motor that is driven separately from the device.The details of this device will be explained below with reference to the embodiments shown in the drawings.

The drawing is a cross-sectional view showing the grinding head main body and the grinding wheel spindle held in the grinding head main body according to this invention attached to the main spindle of the NC milling machine. In the figure, 1 is the main spindle head of the NC milling machine, and 2 is the main spindle. The main body shaft 4 is rotatably incorporated into the head 1 via a bearing 3, and 4 is a DC motor for driving the main body shaft 2 via a gear 5. Reference numeral 6 denotes a grinding head main body that is detachably attached to the main shaft 2 with a bolt 7, and a through hole 8 in which the bolt 7 of the grinding head main body 6 fits is formed to have a slightly larger diameter than the outer diameter of the bolt 7. Then, the grinding head main body 6 is turned at a slight angle about a pin 9 interposed between the grinding head main body 6 and the main main shaft 2 so that it can be attached to the main main shaft 2. Therefore, it is possible to adjust the center of the grindstone main shaft 14, which will be described later, to be mounted in the grinding head main body 6 so that the center of the grindstone main shaft 14 is within a certain range of eccentric position relative to the center of the main main shaft 2.
10 is a drive shaft rotatably inserted into the main shaft 2 via a bearing 11, and 12 is a spline shaft connected to the drive shaft 10 by a flexible coupling 13. 14 is a ball bush guide 15 inside the grinding head main body 6;
This is a grindstone main shaft that has a grindstone 18 at its tip, which is held through a housing 16 and a bearing 17. It is held slidably and can be oscillated in the axial direction. The upper end of this grinding wheel main shaft 14 is connected to the spline shaft 1 described above.
By driving the drive shaft 10 with an AC motor 22 via pulleys 19, 20 and a belt 21,
It is rotationally driven separately from the main body shaft 2 via a spline shaft 12 connected to a drive shaft 10 . A spring 23 is press-fitted between a cover member 24 attached to the lower part of the grinding head main body 6 and a housing 16 located on the outer periphery of the grindstone main shaft 14, and is rotatably held within the housing 16 by this spring 23. The grindstone main shaft 14 is always pressed upward. 25 passes through the drive shaft 10 and the spline shaft 12,
This is an oscillating bar whose lower end is in contact with the upper end surface of the grindstone main shaft 14, and the upper end surface of this oscillating bar 25 is in contact with an elliptical cam driven by a hydraulic motor 26. As the oscillating bar 25 moves up and down, the grindstone main shaft 14 oscillates against the elasticity of the spring. Note that a gap l is formed between the outer peripheral surface of the oscillating bar 25 and the inner peripheral surface of the spline shaft 12, and the grinding head main body 6
If the grinding wheel spindle 14 is eccentrically mounted relative to the main body spindle 2 of the NC milling machine, the grinding wheel spindle 14
Spline shaft 1 connected with spline
The inner peripheral surface of the oscillating bar 25 and the outer peripheral surface of the oscillating bar 25 should not be in contact with each other.

In the above configuration, the grinding head body 6 is attached to the main body spindle 2 of the NC milling machine in a state eccentric by a predetermined amount, and the grinding wheel spindle 14 having the grindstone 18 at the tip, which is held by the grinding head body 6, is attached to the main body spindle 2.
After spline connection is made to the spline shaft 12 inserted inside the machine, and a cam, which is a workpiece, is set on the main body table (not shown) of the NC milling machine, the motor 4 is operated at a speed set to conditions suitable for grinding. 22 and 26 respectively, the grinding wheel main shaft 14 is independently rotated by the AC motor 22 via the pulleys 19 and 20, the belt 21, the drive shaft 10, the flexible coupling 13, and the spline shaft 12, and the grinding wheel main shaft 1
Since the grinding head main body 6, which rotatably and slidably holds the grinding head 4, rotates together with the main main shaft 2 in an eccentric state with respect to the main main shaft 2, the grinding wheel main shaft 14 rotates around the axis of the main main shaft 2. The oscillating bar 25 rotates planetarily, and the oscillating bar 25 moves up and down due to the rotation of the elliptical cam 27, thereby oscillating in the axial direction. In this state, if a grinding feed is given to the cam by numerical control of the NC milling machine and the cam is ground, the axial oscillation of the grindstone main shaft 14 can prevent the occurrence of grinding marks and provide a clean finished surface. At the same time, since the machine is driven by numerical control, processing accuracy is improved compared to conventional grinding methods, and production efficiency is greatly improved due to automation and labor saving. In addition, since the grinding wheel main shaft 14 can be made eccentric to the main body main shaft 2, it is possible to set an arbitrary minute depth of cut.Furthermore, the grinding wheel main shaft 14 is driven by a dedicated AC motor 22 and has a large shaft diameter. , capable of heavy-duty grinding compared to commercially available air-driven grinding attachments. Furthermore, the present invention enables cam grinding of complex three-dimensional shapes by simultaneously controlling the one-axis additional function of the numerical control device in combination with an NC rotary table or NC index. Further, the grinding head main body 6 and the grinding wheel main shaft 14 according to this invention can be easily attached to or detached from the main main shaft 2 of the NC milling machine, and furthermore, since the main main shaft 2 and the grinding wheel main shaft 14 are driven separately, the grinding wheel main shaft 14 can be held. Grinding head body 6
By removing the main shaft 2 from the main body spindle 2, the NC milling machine used in this invention can be used as a normal NC milling machine. In addition, this invention uses a flexible coupling to enable eccentricity of the grinding wheel main shaft, and there is no need to move the driving part according to the eccentricity of the grinding wheel main shaft, and the structure is simple. Since it is driven by a motor, the rotation speed can be freely selected and high-speed eccentric movement is also possible.

As explained above, according to this invention, cutting feed in the direction perpendicular to the axial direction can be given to the grindstone main shaft 14 by simply rotating the main main shaft 2 within the main spindle head 1. In particular, the structure for this purpose is Since the upper end of the grinding head body 6 is eccentrically fixed to the lower end of the main body spindle 2 instead of within the main body spindle 2, the eccentricity setting amount of the grinding head main body 6 with respect to the main body spindle 2 can be changed, and the depth of cut can be changed. can be set freely. That is, when the main body spindle 2 is rotated at a constant speed, the cutting depth of the grindstone spindle 14 changes in proportion to the rotation angle, but the cutting speed does not change. Here, when the eccentricity setting amount is changed, the cutting speed changes even if the rotational speed of the main body spindle 2 remains constant. Conversely, if the rotational speed of the main body spindle 2 is changed while keeping the set eccentricity constant, the cutting speed can be changed. Since it has both of these properties, if the amount of eccentricity itself can be changed, the setting range of the depth of cut can be widened.

Further, since the grindstone main shaft 14 can be rotated and oscillated in the axial direction by the oscillation applying mechanism, unlike simply rotating at a fixed position, a highly accurate and smooth finished surface can be obtained without leaving any grinding marks.

Furthermore, the parts that undergo oscillating motion are simply the grinding wheel main shaft 14 and the housing 16, and the entire body is not oscillated. Since the oscillating bar 25 is pressed upward by the oscillating cam, the oscillating bar 25 can be oscillated by an elliptical cam or the like, which further simplifies the process.

Furthermore, even though the grinding head body 6 is fixed to the lower end of the main body spindle 2 which is rotatably supported by the main spindle head 1, when the main body spindle 2 is rotated, the grinding wheel spindle 14 is eccentrically caused. obtain. this is,
A drive shaft 10 that is rotatably supported within the main body main shaft 2, and a spline shaft 12 that is rotatably supported within the upper part of the grinding head main body 6.
This is because they are connected by a flexible coupling ring 13. That is, the eccentric operation described above is possible by simply supporting the drive shaft 10 in the main shaft 2 so that it can only rotate, and by supporting the spline shaft 12 in the upper part of the grinding head main body 6 so that it can only rotate. The structure can be significantly simplified.

In addition, since the upper end of the grinding wheel main shaft 14 is spline-fitted to the lower end of the spline shaft 12, the spline shaft 12 is connected to the grinding head main body 6 even though the grinding wheel main shaft 14 is raised and lowered together with the housing 16 within the grinding head main body 6. Just by rotatably supporting the inner upper part, the spline shaft 1
The rotational force can be reliably transmitted from 2 to the grinding wheel main shaft 14,
The structure is very simple.

Furthermore, since the through hole of the spline shaft 12 has a larger diameter than the oscillating bar 25, even if the grinding head main body 6 is operated eccentrically with respect to the main shaft 2, no bending force is applied to the oscillating bar 25, and the grinding head can freely eccentrically move. obtain.

[Brief explanation of the drawing]

The drawing is a sectional view showing the grinding head main body according to this invention and the grinding wheel main shaft held within the grinding head main body attached to the main shaft of the NC milling machine. 2...Main main shaft, 6...Grinding head main body, 9...
... Pin, 10 ... Drive shaft, 12 ... Spline shaft, 13 ... Flexible coupling, 14 ... Grinding wheel main shaft, 15 ... Ball bush guide, 17 ... Bearing, 18 ... Grinding wheel, 22
...AC motor, 23...Spring, 25...
Oscillator bar, 26...Hydraulic motor, 27...
oval cam.

Claims (1)

[Scope of utility model registration request] For the spindle head of machine tools such as NC milling machines,
A grinding head that is rotatable, capable of oscillating in the axial direction, and capable of feeding cuts in a direction perpendicular to the axial direction, in which a hollow cylindrical main shaft 2 is rotatably mounted on the main shaft head 1. A hollow cylindrical grinding head main body 6 is eccentrically mounted on the lower end of the main main shaft 2, and the eccentricity is adjustable. The housing 16 is slidable in the axial direction and is mounted in a state where it is constantly pressed upward in the axial direction by a spring 23.
A grinding wheel main shaft 14 is rotatably supported inside the grinding head main body 6, and a spline shaft 12 is mounted on the upper part of the grinding head main body 6.
The upper end of the grindstone main shaft 14 is spline-fitted to the lower part of the spline shaft 12, and the drive shaft 10 is rotatably supported within the main main shaft 2, and the lower end of the drive shaft 10 and The spline shaft 1
The upper end of the oscillating bar 25 is loosely fitted through the drive shaft 10 and the spline shaft 12, and the lower end of the oscillating bar 25 is connected to the grinding wheel main shaft 1.
4, and the spline shaft 1
The through hole 2 is made larger in diameter than the outer diameter of the oscillating bar 25, and an oscillating mechanism is connected to the upper end of the oscillating bar 25 to cause the grinding wheel main shaft 14 to oscillate in the axial direction within the grinding head body 6 together with the housing 16. A rotation imparting mechanism is connected to the upper part of the drive shaft 10 to rotate the grindstone main shaft 14 in the housing 16 via the flexible coupling 13 and the spline shaft 12 in the grinding head main body 6, thereby imparting rotation to the main main shaft 2. By applying rotation through the mechanism, the main shaft 2 of the main body
A main spindle head for a machine tool characterized in that a grinding wheel main spindle 14 is eccentrically moved in a direction orthogonal to the axial direction to give cutting feed through a grinding head main body 6.