JP4132577B2 - Internal processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and a tool for machining an inner peripheral surface of a workpiece having a cylindrical inner peripheral surface.
[0002]
[Prior art]
Conventionally, the following are known as means for cutting the cylindrical inner peripheral surface of a workpiece.
[0003]
A) Internal cutting: A cutting tool is fixed to the end of the tool shaft, and the tool shaft is brought into contact with the inner peripheral surface of the workpiece while rotating the tool shaft at a high speed. Cutting is performed (see, for example, JP-A-10-156610).
[0004]
B) Grinding: While rotating the grinding wheel shaft to which the grinding wheel is fixed at high speed, the outer circumferential surface of the grinding wheel is brought into contact with the inner circumferential surface of the workpiece, and the inner circumferential surface is ground.
[0005]
[Problems to be solved by the invention]
Some workpieces have inner peripheral surfaces made of different materials. An example is shown in FIG. The illustrated workpiece 20 is a sun gear of a planetary gear device provided in an automatic transmission of a vehicle, and its main body is integrally formed of a relatively hard steel material such as carbon steel, and teeth 22 are formed on its outer peripheral surface. ing. Of the inner peripheral surface of the workpiece 20, the inner peripheral surface 24 of the front half is exposed as it is, and the inner peripheral surface 24 is so fixed that a clutch (not shown) is fixed inside the inner peripheral surface 24. The inner diameter is set. On the other hand, a cylindrical bearing 28 made of a non-ferrous metal material such as copper alloy or white metal (lead-based bearing alloy) is fixed inside the inner peripheral surface 26 of the latter half by means such as press-fitting. The input shaft of the automatic transmission is inserted so as to be relatively rotatable.
[0006]
In such a workpiece 20, if both the inner peripheral surface 24 made of the steel material and the inner peripheral surface 29 of the bearing 28 made of non-ferrous metal are to be machined by the cutting process of A), the inner peripheral surface 24 is too hard. For this reason, the tool is worn out quickly and the tool must be replaced frequently. In some cases, the tool may be broken. On the other hand, if the inner peripheral surfaces are to be processed by the grinding process of B), the non-ferrous metal alloy that is the material of the bearing 28 is soft and has high adhesiveness, so that the grindstone is easily clogged, and the cutting by the abrasive grains is performed. There is an inconvenience that the surface accuracy is lowered due to the remarkable marks and the rise around the cutting marks.
[0007]
Therefore, in order to satisfactorily machine both the inner peripheral surfaces 24 and 29 using the conventional method, the work 20 is first set on a boring machine and the inner peripheral surface 29 of the bearing 28 is cut, and then the work 20 Is removed from the boring machine and this time is set on the internal grinding machine, and the inner peripheral surface 24 is ground here, which is extremely inefficient. Further, in addition to the two machine tools, a work transfer device installed between the two machines must be provided, and the facility becomes large. Furthermore, since both inner peripheral surfaces are machined by different machine tools, there is a drawback that it is difficult to obtain a high concentricity between the inner peripheral surfaces 24 and 29.
[0008]
In view of such circumstances, an object of the present invention is to provide an inner surface machining method and an inner surface machining tool capable of efficiently and highly accurately machining workpiece inner peripheral surfaces of different materials with simple equipment.
[0009]
[Means for Solving the Problems]
As means for solving the above problems, the present invention provides a cylindrical first inner peripheral surface made of a first material, and a second material having a lower hardness and a higher adhesiveness than the first material. A method for machining both inner peripheral surfaces of a work having the first inner peripheral surface and a cylindrical second inner peripheral surface having a different diameter , the single tool shaft , The grinding wheel and the cutting tip are shifted in the axial direction while projecting in the radial direction from the tool shaft, and the grinding wheel and the cutting tip having a smaller radial dimension are positioned on the tip side of the tool shaft. fixed advance to, while maintaining the workpiece in the spindle tip, while rotating the spindle and the tool axis, of the large diameter of the first inner peripheral surface and said second inner circumferential surface by inserting the tool axis from the side of the peripheral surface, the outer circumference of the grinding wheel to said first inner circumferential surface Are contacted and the grinding step of grinding the first inner circumferential surface, while rotating the spindle and the tool axis, the diameter of the first inner peripheral surface and said second inner circumferential surface By inserting the tool shaft from the inner peripheral surface side, the cutting tool is brought into contact with the second inner peripheral surface to perform a cutting process of cutting the second inner peripheral surface.
[0010]
According to this method, the first inner peripheral surface that is relatively hard and has low adhesion and the second that is relatively soft and has high adhesion using a single machine tool and tool without removing the workpiece from the spindle. Can be machined with high precision by grinding and cutting, respectively.
[0011]
The present invention has, for example, a main body made of a steel material, and a cylindrical bearing made of a non-ferrous metal alloy having a lower hardness and higher adhesion than the steel material is fixed to a part of the inner peripheral surface of the main body. It is particularly suitable for machining of workpieces. For this workpiece, the inner peripheral surface of the bearing is cut by the cutting step, and the inner peripheral surface where the main body other than the portion where the bearing is fixed is exposed is ground by the grinding step. Thus, each inner peripheral surface can be processed with high accuracy.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the workpiece 20 shown in FIG. 5 is processed.
[0014]
FIG. 1 shows an example of a machine tool for carrying out the method of the present invention. The machine tool includes a bed 10 on which a work driving device 12 and a tool driving device 14 are arranged in opposition to each other.
[0015]
The work drive device 12 includes a head stock 15, and a main shaft (not shown) is rotatably supported on the head stock 15 in a state of extending in the Z-axis direction (left-right direction in FIG. 1). A main shaft drive motor 16 is connected to the rear end (left end in FIG. 1) of the main shaft, and a chuck 18 for gripping the workpiece 20 shown in FIG. 5 is provided at the front end (right end in the figure). Then, when the main shaft drive motor 16 operates in a state where the main body of the work 20 is held by the chuck 18, the work 20 is rotationally driven around the central axis Xw (see FIG. 3) integrally with the main shaft (not shown). It has come to be.
[0016]
The tool driving device 14 includes a fixed base 30, and the fixed base 30 is fixed on the bed 10. An X-axis table 32 is installed on the fixed base 30 so as to be slidable in the X-axis direction (vertical direction in FIG. 1) orthogonal to the main shaft. The X-axis table 32 is provided with an X-axis drive motor 34 and a feed not shown. The screw mechanism is slid in the X-axis direction.
[0017]
On the X-axis table 32, a Z-axis table 36 is installed so as to be slidable in the Z-axis direction (left-right direction in FIG. 1) parallel to the main axis, and this Z-axis table 36 includes a Z-axis drive motor 38 and a not-shown illustration. The feed screw mechanism is slidably driven in the Z-axis direction. A tool support base 40 is provided on the Z-axis table 36.
[0018]
A spindle is rotatably supported on the tool support 40, and the spindle also extends in the Z-axis direction like the main shaft. A tool driving motor 44 is connected to the rear end (right end in FIG. 1) of the spindle, and a tool gripping portion 42 is provided at the front end (left end in the figure). The inner surface processing tool T according to the present invention is detachably held by the tool holding portion 42.
[0019]
As shown in FIG. 2, the inner surface machining tool T includes a single tool shaft 46, the rear end side of which is gripped by the tool gripping portion 42, and the cutting tool 47 and the grinding wheel 50 are fixed to the front end side. It has come to be.
[0020]
Specifically, a grindstone mounting portion 46a having a smaller diameter than other portions is formed on the tip side of the tool shaft 46, and a tip shaft portion 46b having a smaller diameter than the grindstone mounting portion 46a is further formed on the outer side thereof. An inclined surface 46d is formed on a part of the distal end surface of the distal end shaft portion 46b so as to face the distal end side and radially outward. A cutting tool 47 (sword tool in the illustrated example) 47 is erected on the inclined surface 46d in the normal direction of the inclined surface 46d, and the cutting blade 48 at the tip is on the tip side of the tool shaft 46 and radially outside. It is in a state facing.
[0021]
The grinding wheel 50 has a ring shape with a through hole in the center, and a recess 50a that opens forward is formed around the front side portion of the through hole. On the other hand, in the tool shaft 46, a male screw 46c is carved in a front portion of the grindstone mounting portion 46a (that is, a root portion of the small diameter shaft 46b), and the grinding wheel 50 is fitted to the outside of the grindstone mounting portion 46a. In this state, the nut 51 is screwed onto the male screw 46c and tightened to the back side of the recess 50a, so that the grinding wheel 50 is sandwiched between the nut 51 and the rear end side stepped portion of the grindstone mounting portion 46a. It has become.
[0022]
The radial dimension from the center axis Xt of the tool shaft 46 to the tip (cutting blade) 48 of the cutting tool 47 is larger than half the inner diameter (inner radius) of the bearing 29 in the workpiece 20 shown in FIG. The outer diameter of the grinding wheel 50 (the outer diameter in a new state before dressing) is set to be smaller than the inner diameter of the inner peripheral surface 24 of the workpiece 20.
[0023]
On the other hand, a dressing tool 54 is supported on the workpiece driving device 12 side via an arm 52 as shown in FIG. The arm 52 extends from the workpiece driving device 12 side to the tool driving device 14 side and has a substantially L shape in plan view extending radially inward from the tip thereof, and the dressing tool 54 faces inwardly to the tip surface. Is fixed. The dressing tool 54 is for shaping the grinding wheel 50, and a well-known dressing diamond or the like is applicable.
[0024]
Next, an inner surface machining method using this machine tool will be described.
[0025]
{Circle around (1)} In the initial stage, the spindle is retracted from the workpiece 20 so that the central axis of the workpiece 20 and the central axis of the spindle are substantially matched. Then, the workpiece 20 is mounted on the chuck 18 at the front end of the main spindle, and the tool shaft 46 of the inner surface processing tool T is mounted on the tool gripping portion 42 at the front end of the spindle.
[0026]
(2) The workpiece 20 and the spindle are respectively rotated at a set target rotational speed, and the cutting tool 48 at the tip of the inner surface machining tool is moved to the position just before the bearing 28 in the workpiece 20 by the Z-axis drive motor 38. Fast forward. At this time, the direction of rotation of the workpiece 20 and the direction of rotation of the spindle (arrows in FIG. 3A) may be the same or opposite.
[0027]
(3) The spindle is gently moved in the X-axis direction by the X-axis drive motor 34 (cut feed), and the cutting blade 48 at the tip of the cutting tool is positioned at a radial position so as to contact the bearing inner peripheral surface 29 of the workpiece 20. . Then, the cutting tool 47 is cut and fed by the Z-axis drive motor 38 at a predetermined feed speed in the direction of the arrow in FIG. By this operation, the bearing inner peripheral surface 29 can be cut in a state where the workpiece center axis Xw and the tool center axis Xt are eccentric by a predetermined amount e (FIG. 3A).
[0028]
(4) After the cutting process is completed, with the workpiece 20 still mounted on the chuck 18, the tool center axis Xt is once returned to a position substantially matching the workpiece center axis Xw, and then the inner surface machining tool T is further advanced. The grinding wheel 50 is positioned inside the work inner peripheral surface 24. Then, after switching the spindle rotational speed to a preset grinding rotational speed, this time, the outer peripheral surface of the grinding wheel 50 is brought into contact with the inner peripheral surface 24 from the inside, and the inner peripheral surface is ground (FIG. 3). (B)). At this time, it is possible to further improve the surface accuracy by oscillating the grinding wheel 50 integrally with the tool shaft 46 (slightly vibrating in the axial direction).
[0029]
(5) After the machining is completed, the spindle and the inner surface machining tool T at the tip thereof are returned to their initial positions, the rotation of the spindle and spindle is stopped, and the workpiece 20 is replaced.
[0030]
(6) When the grinding wheel 50 is worn by the grinding process or when the shape is broken, the grinding wheel 50 is brought into contact with the dressing tool 54 using the X-axis drive motor 34 and the Z-axis drive motor 38. Do that dress. After dressing, the cutting amount of the grindstone at the time of grinding is corrected in the increasing direction by the same amount as the dress amount. Further, the cutting blade 48 also corrects the cutting amount of the cutting tool 47 in the increasing direction by the same amount as the wear amount. This correction may be based on empirical values such that the predetermined correction amount is increased to the cutting amount every time a predetermined number of workpieces are processed, or the measured workpiece inner diameter is measured and the measured value and target dimension are measured. The correction value may be calculated from the difference between.
[0031]
According to the above method, of the inner peripheral surface of the workpiece 20, the inner peripheral surface 24 where the steel material as the main body material is exposed, that is, the first inner periphery having a relatively high hardness and low adhesiveness. As for the surface, by contacting the outer peripheral surface of the grinding wheel 50 with this, the inner peripheral surface can be ground with high precision, while the bearing inner peripheral surface 29 made of a non-ferrous metal alloy, that is, relatively hard. With respect to the second inner peripheral surface which is low and has high adhesiveness, the inner peripheral surface 29 can be precisely machined by bringing the cutting blade 48 of the cutting tool 47 into contact therewith.
[0032]
Moreover, since the cutting and grinding can be performed with a single machine tool while the workpiece 20 and the inner surface machining tool T are held on the chuck 18 and the tool holding portion 42, respectively, simple equipment and efficiency are achieved. Both processes can be performed well, and high concentricity can be obtained for both inner peripheral surfaces 24 and 29.
[0033]
Even if the inner peripheral surfaces 24 and 29 have different inner diameters, both the inner and outer surfaces 24 and 29 can be changed by changing the eccentric amount e between the workpiece center axis Xw and the tool center axis Xt during cutting and grinding according to the inner diameter. The peripheral surfaces 24 and 29 can be processed without changing the tool.
[0034]
Furthermore, even if the radial protrusion dimension of the cutting blade 48 and the outer diameter of the grinding wheel 50 change due to wear of the cutting blade 48 or wear / dress of the grinding wheel 50, it is only necessary to correct the cutting amount accordingly. There is also an advantage that processing accuracy can be maintained.
[0035]
In the first embodiment, among the two inner peripheral surfaces 24 and 26 formed on the main body of the workpiece 20, the bearing 28 is fixed inside the inner peripheral surface 26 on the small diameter side. As shown in FIGS. 4A and 4B as the second embodiment, when the bearing 28 is fixed to the inner peripheral surface 24 on the large diameter side (that is, the inner peripheral surface 26 on the small diameter side is the first inner surface 26). The present invention can also be applied to the case of a peripheral surface.
[0036]
In this case, as shown in the figure, for example, a small-diameter shaft portion 46e is formed on the tip end side of the tool shaft 46, and a further smaller-diameter grindstone mounting portion 46a is formed on the tip end side of the tool shaft 46. On the other hand, a small-diameter grinding wheel 50 is fixed to the large-diameter shaft portion on the rear side of the small-diameter shaft portion 46e, and an inclined surface 46d similar to that of the first embodiment is formed. What is necessary is just to fix. Also in this case, the radial dimension from the center of the tool shaft 46 to the cutting blade 48 is set to be smaller than half the inner diameter (inner radius) of the bearing 28, and the outer diameter of the grinding wheel 50 is set to the inner diameter of the work inner peripheral surface 26. It is more preferable to set it smaller than half.
[0037]
In addition, for example, the present invention can take the following embodiments.
[0038]
In the present invention, regardless of the specific shape of the cutting tool 47, various cutting tools such as a bending tool, a single-edged tool, a boring tool, a clamp tool, etc. can be applied in addition to the sword tool as shown in the figure. .
[0039]
The material of the inner peripheral surface of the workpiece according to the present invention is not limited to the above, but the first inner peripheral surface made of the first material suitable for grinding (that is, the inner periphery having relatively high hardness and low adhesion) The present invention is widely applied to machining of a workpiece having both a surface and a second inner peripheral surface made of a second material suitable for cutting (that is, an inner peripheral surface having relatively low hardness and high adhesiveness). it can. For example, as the second material, the present invention can be applied to non-ferrous metal materials such as the copper alloy, lead alloy, and aluminum alloy as well as non-metal materials such as carbon.
[0040]
Regarding the types of workpieces, the present invention can be widely applied to workpieces having a plurality of inner peripheral surfaces made of different materials regardless of the sun gear of the automatic transmission as described above.
[0041]
In the above-described embodiment, the grinding process is performed after the cutting process is performed, but the cutting process may be performed after the grinding process is performed regardless of the order.
[0042]
【The invention's effect】
As described above, according to the present invention, the grinding wheel and the cutting tool are fixed to a single tool shaft, and the first inner peripheral surface and the second inner periphery having a lower hardness and higher adhesiveness. While the workpiece having a surface is held on the main shaft, the first inner circumferential surface is machined by the grinding wheel and the second inner circumferential surface is machined by the cutting tool. There is an effect that both inner peripheral surfaces can be machined efficiently and accurately with simple equipment.
[Brief description of the drawings]
FIG. 1 is a plan view showing a machine tool for carrying out an inner surface machining method according to a first embodiment of the present invention.
FIG. 2 is a sectional front view showing a main part of the inner surface processing tool according to the first embodiment.
3A is a cross-sectional front view showing a cutting process according to the first embodiment, and FIG. 3B is a cross-sectional front view showing a grinding process.
FIG. 4A is a sectional front view showing a cutting process according to the second embodiment, and FIG. 4B is a sectional front view showing a grinding process.
FIG. 5 is a cross-sectional front view showing an example of a workpiece having both a first inner peripheral surface and a second inner peripheral surface.
[Explanation of symbols]
20 Workpieces 24 and 26 Workpiece inner peripheral surface 28 with exposed main body portion Bearing 29 Bearing inner peripheral surface 46 Tool shaft 47 Cutting tool 50 Grinding wheel T Internal surface machining tool

Claims (2)

A cylindrical first inner peripheral surface made of a first material and a diameter different from that of the first inner peripheral surface made of a second material having a lower hardness and higher adhesiveness than the first material. A method for machining both inner peripheral surfaces of a workpiece in which a cylindrical second inner peripheral surface is aligned in the axial direction ,
A single tool shaft having a small radial dimension between the grinding wheel and the cutting tip, wherein the grinding wheel and the cutting tip are displaced in the axial direction while projecting radially from the tool shaft. It is fixed so that it is located on the tip side of the tool axis ,
While rotating the spindle and the tool axis while holding the workpiece at the tip of the spindle, the tool axis is rotated from the large inner diameter side of the first inner peripheral surface and the second inner peripheral surface. by inserting a grinding step of the contacting the outer peripheral surface of the grinding wheel to the first inner circumferential surface grinding the first inner peripheral surface,
By rotating the main shaft and the tool shaft, the tool shaft is inserted from the large-diameter inner peripheral surface side of the first inner peripheral surface and the second inner peripheral surface, whereby the second An inner surface machining method comprising: performing a cutting process of cutting the second inner circumferential surface by bringing the cutting tool into contact with the inner circumferential surface.   2. The inner surface processing method according to claim 1, wherein the workpiece has a main body made of a steel material, and a part of an inner peripheral surface of the main body is made of a non-ferrous metal alloy having lower hardness and higher adhesion than the steel material. A cylindrical bearing is fixed, the inner peripheral surface of this bearing is cut by the cutting step, and the inner peripheral surface where the main body other than the portion where the bearing is fixed is exposed is the An inner surface processing method characterized by grinding by a grinding process.

Images