JP2000117524A - Cutting method and cutting unit used in this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly precisely cut and machine the end face of a work by means of a lightweight and compact shaft head. SOLUTION: An eccentric shaft 5 on which a cutting blade 4 is fixed is supported on the spindle shaft 2 of a shaft head revolvably around the axis Y of the spindle shaft 2 and rotatably around its own axis Y. By effecting an axial feed as the eccentric shaft 5 is revolved togetherwith the spindle shaft 2, the inside diameter surface Fi of a work W is machined and by rotating the eccentric shaft 5 with a feed stopped, as the cutting blade 4 fixed on the eccentric shaft is moved in the direction of an inside diameter, the end face Fe of the work W is machined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting method for processing a work fixedly mounted on a processing machine such as a boring machine by turning a cutting blade, and a cutting unit for performing the method.

[0002]

2. Description of the Related Art Generally, in peripheral surface turning using a lathe as a processing machine, a workpiece is processed by feeding a cutting blade on a tool post while clamping and rotating the workpiece on a chuck on a spindle side. Will be In the end face cutting using a milling machine as a processing machine, the work on the end face of the workpiece is fixed by feeding the work on a table and feeding the table with the work fixed vertically and horizontally to a rotating milling machine attached to the spindle head. Done.

[0003]

When the workpiece has a complicated shape, or when the central axis of the workpiece and the central axis of the inner diameter surface or the end surface to be machined are eccentric, examples of such a workpiece include oil. Although there is a pump body, the center of gravity of the work cannot be aligned with the center of the main spindle.According to the lathe processing that rotates the work, the rotational imbalance of the main spindle that clamps the work becomes large, and the machining accuracy of the inner diameter surface and end face There was a problem that it could not be guaranteed.

Therefore, when the above-described oil pump body is machined, butting is used for machining the inner diameter surface. In this processing method, as shown in FIG. 5, while rotating the work W about the center of the inner diameter surface as a rotation axis, the cutting edge C1 is cut into the end surface to cut the inner surface F1 of the gear chamber. Similarly, the outer diameter surface F2 of the crescent is processed by cutting with the cutting blade C2, and the inner diameter of the crescent is similarly cut with the cutting blade C3 while rotating the work W around the center of the inner surface of the crescent as a rotation axis. Each peripheral surface is cut by three-stage processing of processing the surface F3. However, such a processing method cannot avoid the occurrence of an error in the position of each cutting blade in the cutting direction. Therefore, a step is formed on the processing end face, and the precision of a precision component such as an oil pump body that requires high end face precision to prevent oil leakage cannot be guaranteed.

[0005] As a method of processing the end face of the work, there is a facing method. In this processing method, as shown in FIG. 6, a fixed work W is processed by feeding the work W in the radial direction of the end face of the work while rotating the cutting blade C on the spindle head side around the main shaft. However, in this method, it is necessary to provide a slide mechanism for rotating the cutting blade C in the radial direction by rotating with the spindle on the spindle head side, so that the weight of the spindle increases and the rotational imbalance increases accordingly. Therefore, high processing accuracy cannot be guaranteed. Also, if the weight of the main shaft is heavy, the load applied to the support bearings of the shaft also increases, which is disadvantageous in maintaining the durability and life of the device.

Accordingly, an object of the present invention is to provide a cutting method capable of performing high-accuracy end face cutting with a work fixed and a lightweight and compact cutting unit used therefor.

[0007]

In order to achieve the above object, a cutting method according to the present invention revolves around a spindle shaft together with a continuously rotating spindle shaft and is eccentric with respect to the spindle shaft. The end face of the workpiece is machined by rotating the cutting blade fixed to the eccentric shaft in the radial direction by the rotation of the eccentric shaft around the axis.

[0008] The radial movement of the cutting blade,
The rotation of the spindle shaft around its axis is transmitted to the eccentric shaft via a coaxial type speed reduction mechanism and transmitted to the eccentric shaft at an appropriate speed under the control of the speed reduction mechanism. It is effective to change the phase.

Further, in order to simultaneously perform the inner diameter processing by the above-mentioned processing method, the eccentric shaft is revolved around the axis of the spindle shaft together with the spindle shaft while feeding the eccentric shaft in the spindle axial direction. It is effective to machine the end face of the work by machining the inner diameter surface of the work and rotating the eccentric shaft while maintaining the revolution around the axis of the spindle shaft.

Next, as an apparatus for performing the above-mentioned cutting, the cutting unit of the present invention comprises a base, a spindle shaft rotatably supported by the base, and a base supported by the base.
Spindle driving means for continuously rotating the spindle shaft;
An eccentric shaft that is rotatably supported by the spindle shaft with the shaft center eccentric with respect to the axis of the spindle shaft and has a fixed cutting blade for processing a work, and eccentric shaft driving means for rotating the eccentric shaft. It is characterized by.

In order to particularly reduce the load on the spindle shaft, the spindle shaft and the eccentric shaft are provided with a gear mechanism having a predetermined gear ratio and a harmonic drive mechanism having a speed ratio opposite to the predetermined gear ratio. It is effective to adopt a configuration in which the eccentric shaft driving means is connected to the harmonic drive mechanism and is a continuous rotary driving means supported on a common base with the spindle driving means.

[0012]

According to the first aspect of the present invention, such a configuration is adopted.
According to the present invention described in (1), the work is performed by feeding the eccentric movement of the cutting blade by the rotation of the eccentric shaft revolving with the spindle shaft without rotating the work, and the work end face is simply moved from the outer diameter side to the inner diameter side. Processing can be performed with one cutting by one cutting blade. Therefore, according to this method, compared to a machining method such as milling in which an end face is machined with a plurality of different cutting blades, there is no longer any effect of an error in the mounting position between the cutting blades, thereby improving the machining accuracy. Can be done. Further, since the feed of the cutting blade is performed only by the eccentric movement due to the rotation of the eccentric shaft, there is no occurrence of excessive movement due to the inertial force.

According to the second aspect of the present invention, the use of the coaxial type speed reduction mechanism controls the speed reduction mechanism while revolving the eccentric shaft using the rotation of the spindle shaft with a lightweight and compact mechanism. Thus, the phase of the eccentric shaft can be changed at an arbitrary rotation speed, whereby a desired feed speed can be given to the cutting blade independently of the revolution speed of the eccentric shaft.

Further, according to the third aspect of the present invention, since the inner diameter surface and the end surface of the work can be machined in one step without changing the cutting blade, the trouble such as setup change can be eliminated. Further, since there is no processing error due to the replacement of the cutting blade for the above-described reason, not only the processing accuracy of both processing surfaces can be improved, but also the positional accuracy between the surfaces can be improved. In addition, since the fixed position of the cutting blade can be set to any position inside or outside in the radial direction, even for workpieces with different inside diameters, it is possible to process the inside diameter by changing the position of the cutting blade only by changing the position of the cutting blade It is.

Next, according to the apparatus of the present invention, the operation of continuously rotating the cutting blade in the radial direction of the work can be realized by the continuous rotating means of the spindle shaft and the mechanism of rotating the eccentric shaft. Therefore, the rotating part of the shaft head that supports the cutting blade can be made lightweight and compact to reduce the inertia force, and by reducing the spindle shaft support load, the turning trajectory of the cutting blade is stabilized and machining accuracy is improved. Can be improved.

According to a fifth aspect of the present invention,
By stopping the eccentric shaft driving unit when the spindle is rotated by the spindle driving unit, the eccentric shaft driving unit is used as a fixed reaction force element in the harmonic drive mechanism,
Since a driving state in which decelerated rotation is output to the eccentric shaft occurs, a revolving driving state of the eccentric shaft in which the eccentric shaft rotates synchronously with the spindle shaft is generated by offsetting with the speed increasing rotation by the speed increasing gear. By operating the eccentric shaft driving means in the same state, a driving state is generated in the harmonic drive mechanism in which a minute relative rotation with respect to the rotation of the spindle shaft is output to the eccentric shaft. Therefore, the switching between the driving state for inner diameter cutting for revolving the eccentric shaft together with the spindle shaft and the driving state for end face cutting for eccentric displacement is performed only by the non-driving / driving of the eccentric shaft driving means fixed to the apparatus base. Since it becomes possible, there is no need to dispose an eccentric shaft driving means, which causes an increase in the weight of the spindle shaft, so that the load on the spindle shaft supporting portion can be reduced and the machining accuracy can be further improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. First, a schematic concept of a cutting unit (hereinafter, referred to as a shaft head) of the present invention will be described.
FIG. 1 schematically shows the shaft head in a sectional view. The shaft head is used by being attached to a processing machine such as a boring machine as a base, and includes a base 1, a spindle shaft 2 rotatably supported by the base 1, a spindle shaft 2 supported by the base 1, Spindle driving means 3 for continuously rotating the shaft 2; and eccentricity in which the axis Y is eccentric with respect to the axis X of the spindle 2 so as to be rotatably supported by the spindle 2 and to which a cutting blade 4 for processing a work is fixed. A shaft 5 and eccentric shaft driving means 6 for rotating the eccentric shaft 5 are provided.

The spindle shaft 2 and the eccentric shaft 5 are connected via gears 21 and 22 having a predetermined speed increasing gear ratio and a harmonic drive mechanism 7 having a reduction speed ratio opposite to the predetermined gear ratio. The driving means 6 includes a harmonic drive mechanism 7
And a continuous rotation driving means supported on a common base 1 with the spindle driving means 3.

More specifically, the base 1 is fixed to a bed of a processing machine such as a boring machine via an appropriate axial feed mechanism, and has a cylindrical portion 11 supporting the spindle 2.
And a gear box portion 12 extending on both sides at the rear end.

The spindle shaft 2 is a hollow shaft, and the base 1
Is rotatably supported via a bearing 14 and a bearing 15 on a sleeve 13 fitted and fixed in a shaft hole provided in
The power can be transmitted to a gear 20 fixed to the outer periphery of the rear end by a key, so that the gear 20 can be continuously rotated. Further, the outer periphery of the rearmost end of the spindle shaft 2 is
A gear 23 having the same pitch diameter and the same number of teeth as 0 is rotatably supported.

The spindle driving means 3 is a fully-closed external fan-type motor fixed to the rear end of the gear box section 12, and includes a driving gear 31 fixed to an output shaft thereof. A counter shaft 32 is provided between the output shaft and the spindle shaft 2 and supported by the gear box unit 12, and a gear 31 fixed to the output shaft is provided.
And the gear 20 fixed to the spindle 2
The driving connection is made via a counter reduction gear fixed to the key.

The eccentric shaft 5 is supported by the spindle shaft 2 via a pair of front and rear bearings 21 and 22, and is positioned and supported by a bearing 23 disposed at the front end of the spindle shaft 2 so as not to move in the axial direction. External teeth 51 are formed on the outer periphery of the rear end of the eccentric shaft 5 so as to be located in the gear box portion 12, and these external teeth 51 are bolted to the outer end of the gear 23 on the outer periphery of the rearmost end of the spindle shaft 2. It meshes with the internal teeth of the fixed ring gear 24.

The eccentric shaft driving means 6 includes a gear box 12
And a gear 21 and a gear 22 meshed with a gear 20 and a gear 23 on the spindle shaft 2 on a harmonic drive mechanism 7 as a coaxial deceleration mechanism, respectively. Are arranged, and the gear 21
Is connected to a flex spline 71 of the harmonic drive mechanism 7, and the gear 22 is connected to a circular spline 72.
, And a wave generator 70 is connected to an output shaft of the servomotor 6 via a flexible joint 61.

Here, the relationship between the number of teeth of each gear will be described. Regarding the gears on the spindle shaft 2, the gear 20 and the gear 23 have the same pitch diameter and the same number of teeth, and the gears on the harmonic drive mechanism shaft have the same pitch diameter as the gears 21 and 22 and the same number of teeth. The ratio of the number of teeth is the reciprocal of the speed ratio at the time of input of the flex spline 71 and output of the circular spline 72 of the harmonic drive mechanism 7. For example, the number of teeth of both the gear 20 and the gear 23 is 73, and the number of teeth of the gears 21 and 22 is 5
0:51, the speed ratio when the flex spline 71 of the harmonic drive mechanism 7 is input and the circular spline 72 is output is 51/50, and the ring gear 24 and the external teeth 5
The gear ratio of 1 is 33/23.

As shown in detail in FIG. 2, the cutting blade 4 is attached to the tip of an eccentric shaft 5. In this embodiment, the cutting blade 4 is composed of the outer blade 41 and the inner blade 42, which slightly deviates from the spirit of the present invention, but increases the machining efficiency.
The outer cutter 41 is fixed to the corner of the tip of the eccentric shaft 5 so that the cutting edge slightly protrudes in the outer diameter direction and the axial direction from the outer peripheral surface and the end surface of the eccentric shaft 5, and the inner cutter 42 is the outer peripheral surface of the tip of the eccentric shaft 5. On the inner side, the cutting edge is fixed so as to slightly protrude in the axial direction from the end face.

The shaft head having the above-described structure is driven by a motor to drive power via a counter reduction gear.
0, the spindle shaft 2 is driven to rotate continuously. By this driving, the gear 21 is also driven, the flex spline 71 of the harmonic drive mechanism 7 connected thereto also rotates, and the meshing portion supported by the wave generator 70 connected to the output shaft of the servomotor 6 in a stopped state is supported. The circular spline 72 also rotates at a reduced speed while meshing. The rotation of the circular spline 72 is
The rotation is transmitted to the gear 22, and the speed is increased by an amount that cancels the decelerated rotation at the meshing portion with the gear 23, and the rotation is transmitted to the ring gear 24 as it is. Therefore, the gear 20
The eccentric shaft 5 meshed with the ring gear 24 with the external teeth 51 rotates synchronously around the axis of the spindle shaft 2.

As described above, by rotating only the motor 3 while the servomotor 6 is stopped, an integrally rotating state of the spindle shaft 2 and the eccentric shaft 5 is obtained, and the spindle shaft 2 and the eccentric shaft 5 are attached to the tip of the eccentric shaft 5. The outer cutter 41 and the inner cutter 42 rotate at the rotation speed of the spindle 2. Therefore, in this state, by applying an axial feed to the base 1 in accordance with a desired cutting speed, the two blades 41 and 42 advance while rotating, and the outer blade 41 is rotated.
To obtain the cutting state of the inner surface of the work. At this time, the inner blade 42 idles without contacting the work W. In this case, the speed ratio between the spindle shaft 2 and the eccentric shaft 5 is 1: 1 due to the speed ratio 50/51 of the harmonic drive and the gear ratio 51/50, and the number of revolutions of the cutting blade 4 is 1400 rpm. When you do, it will be the same speed.

Next, when the servo motor 6 is rotated while the motor 3 is rotating, the harmonic drive mechanism 7 is rotated.
Flex spline 71 and circular spline 7
2 meshes with the rotation of the wave generator 70. As a result, a rotational speed difference is generated between the two gears 20 and 23 connected thereto, and the ring gear 24 generates a minute relative rotation with respect to the spindle shaft 2. As a result, the eccentric shaft 5 rotates with respect to the spindle shaft 2. Therefore, at this time, by eliminating the axial feed applied to the base 1, the cutting blade 4 stops moving forward while rotating, the outer blade 41 starts moving in the inner diameter direction, and the inner blade 42 starts moving in the outer diameter direction, Workpiece end face cutting state is obtained. In this case, a change in phase due to rotation of the eccentric shaft 5 with respect to the spindle shaft 2;
That is, the feed speed in the end face processing is the servo motor 6
Is determined by independently controlling the rotation of the output shaft, and can be freely set regardless of the rotation speed of the cutting blade 4.

Next, a specific cutting method using the shaft head will be described. First, as a setup prior to processing, as shown in FIG. 2, a work W previously formed into a substantially predetermined product shape by casting, forging, or the like is fixed to a positioning jig 8 on the spindle side. In this example, the work W is an oil pump body as shown in FIG. 3 and has an inner surface Fi and an end surface Fe of a gear chamber containing an annular outer gear (not shown) fitted therein and an inner gear meshing eccentrically with the outer gear.
(The hatched area in the figure indicates the surface shape). In this work W, the center of the gear chamber (center of the inner gear) Og is the center of the work W (the center of the outer gear) Ow
Is eccentric by a predetermined amount S. Therefore, the center Og of the gear chamber is fixed to the jig 8 so as to be aligned with the axis of the main shaft, the axis of the main shaft and the axis X of the spindle shaft 2 at the shaft head are set and the machining is started.

At the time of machining the inner diameter surface, as shown in FIG. 4, the outer cutter 41 advances while rotating at the radial position shown by the solid line shown in the figure around the axis X (center of the gear chamber) of the spindle shaft 2 as the center of rotation. and performing cutting for machining a workpiece inner surface Fi to the diameter D _{4 1} in. When a predetermined amount of feed is completed, the feed is stopped, and the outer cutter 41 is moved in the outer diameter direction and the inner cutter 4 is moved.
2 is started to move in the outer diameter direction. By this operation, the outer cutter 41 gradually moves in the inner diameter direction while following the trajectories 41 _{2 to} 41 ₁₀ shown by the two-dot chain line in the figure while cutting the work end face. On the other hand, the inner cutter 42 also moves following the trajectory 42 _{2-42 1 0} indicated by the two-dot chain line in FIG while cutting the end face to progressively radially outward. This region of the end face to be cut by the movement of the outer cutter 41 is made from the corner portion connected to the outer diameter surface Fi to the position of radius R _{4 1} inside which shows a double concentric circles in two-dot chain line in FIG., The inner cutter 42 The area of the end face which is cut by the movement of the outer radius R shown by a two-dot chain line in FIG.
₄ Up to position ₂ . In this example, the rotation of the eccentric shaft 5 with respect to the spindle shaft 2 is limited to 123 ° which is half a rotation or less in order to minimize the wrap amount, which is an element for reducing the processing accuracy, in order to minimize the wrap amount. Although it is a cutting area, in principle, by rotating the eccentric shaft 5 to a maximum of 180 °, it is possible to cut to a radial width of up to twice the eccentric amount S.

As described in detail above, according to this forming method, the processing surface of the work W is cut by a single cut of the outer cutter 41 for both the inner diameter surface Fi and the end surface Fe. And their mutual positional accuracy can be kept high. Moreover, the only members that rotate with the spindle shaft 2 are the shaft itself, the eccentric shaft 5 and the respective gears 20, 23, 24 on the spindle shaft 2, and the servo motor 6, the harmonic drive mechanism 7, and the harmonic drive mechanism shaft. Each of the gears 21 and 22 is a member that is supported by the gear box portion in weight. Therefore, the weight of the spindle shaft 2 can be reduced to a necessary minimum, whereby the load on the rotation supporting portion of the spindle shaft 2 can be reduced, and the processing accuracy can be improved.

Although the present invention has been described in detail based on one embodiment in which the present invention is applied to processing of an oil pump body, the present invention is not limited to only the disclosed contents of the above-described embodiment, but may be used for processing other general workpieces. It is applicable to. Also,
It goes without saying that the specific configuration of each unit can be variously modified and implemented within the scope of the matters described in the claims. For example, in the above-described embodiment, in consideration of the cycle time, the outer blade 41 is moved in the inner diameter direction, and the inner blade 42 is moved in the outer diameter direction.
A method of machining the entire end face by partially wrapping the cutting area of 42 was adopted. However, in order to realize the technical idea of the present invention most faithfully, the amount of eccentricity of the eccentric shaft 5 with respect to the spindle shaft 2 was set large. Then, the outer cutter 41 is made to reach the innermost diameter side of the end face within the rotation angle of the eccentric shaft 5 with respect to the spindle shaft 2 within 180 °, and all the processing surfaces are finished by one cutting with a single blade. By doing so, the processing accuracy can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a cutting unit used for cutting according to the present invention.

FIG. 2 is a cross-sectional view illustrating a positional relationship between the cutting unit and a work held by a jig.

FIG. 3 is a plan view showing an oil pump body as an example of a workpiece to which the cutting process of the present invention is applied.

FIG. 4 is an explanatory diagram showing a movement locus of a cutting blade according to the processing method of the embodiment.

FIG. 5 is an explanatory view showing an inner diameter surface processing by a conventional butting process.

FIG. 6 is an explanatory view showing end face processing by conventional facing processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Spindle shaft 3 Fully-closed outer fan type motor (spindle drive means) 4 Cutting blade 5 Eccentric shaft 6 Servo motor (eccentric shaft drive means) 7 Harmonic drive mechanism (reduction mechanism) 21, 22 Gear W Work X Spindle shaft axis Center Y Center of eccentric shaft

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiyuki Ando 10 Takane, Fujii-machi, Anjo City, Aichi Prefecture Inside Aisin AW Co., Ltd. (72) Inventor Teruo Okochi 1-10-10 Takaoka Higashi, Hamamatsu City, Shizuoka Prefecture 55 No. 55, Inventor Kenji Muramatsu, Inventor Kenji Muramatsu 1-10-1 Takaoka Higashi, Hamamatsu-shi, Shizuoka Prefecture 55 Inventor Hideto Watanabe 1-chome, Takaoka Higashi, Hamamatsu-shi, Shizuoka Prefecture No. 10 55 Inside Shinkigi Giken Co., Ltd.

Claims (5)

[Claims] 1. A cutting blade fixed to an eccentric shaft by revolving around the axis of the spindle shaft together with a continuously rotating spindle shaft and rotating around the axis of an eccentric shaft eccentric to the axis of the spindle shaft. A cutting method characterized by processing an end face of a work while moving in a radial direction. 2. The movement of the cutting blade in the radial direction is achieved by transmitting the rotation about the axis of the spindle shaft to the eccentric shaft via a coaxial speed reduction mechanism and appropriately changing the speed under the control of the speed reduction mechanism. The cutting method according to claim 1, wherein the cutting is performed by changing a phase of rotating the eccentric shaft at a unique speed with respect to the rotation of the spindle shaft. 3. An inner diameter surface of a workpiece is machined by feeding the eccentric shaft in the spindle axial direction while revolving the eccentric shaft around the spindle axis together with the spindle shaft. The cutting method according to claim 1 or 2, wherein the end surface of the work is machined by rotating the eccentric shaft while maintaining the revolution. 4. A base, a spindle shaft rotatably supported by the base, a spindle drive means supported by the base and continuously rotating the spindle, and an axis eccentric to the axis of the spindle. An eccentric shaft that is rotatably supported by the spindle shaft and has a fixed cutting blade for processing the work;
An eccentric shaft driving means for rotating the eccentric shaft. 5. The spindle shaft and the eccentric shaft are connected via a gear mechanism having a predetermined gear ratio and a harmonic drive mechanism having a speed ratio opposite to the predetermined gear ratio. 5. The cutting unit according to claim 4, wherein the cutting unit is a continuous rotation drive unit connected to the harmonic drive mechanism and supported on a common base with the spindle drive unit.