JPH06226502A - Method and tool for cutting spherical surface - Google Patents

Abstract

PURPOSE:To provide a method and device capable of cutting efficiently a spherical surface. CONSTITUTION:A tool body 30 fixes four tips 40 having a nose 42, side cutting edge 44 and end cutting edge 46 such that the end cutting edge 46 is inclined to be kept away from the tool axis as it approaches a nose 42. In cutting a spherical surface 12 of a workpiece 10, the cutting tool is fed in the spherical surface 12 every time the cutting tool is rotated with high speed around the axis Lr and the workpiece 10 makes one revolution around the axis Lw with extremely low speed. The cutting is normally performed by the nose 42 and side end cutting edge 44 according to the inclination of the end cutting edge 46, and at the final stage of working the end cutting edge 46 makes contact with the spherial surface 12 for finish working, so that the wear of the end cutting edge 46 is few, the small number of times of polishing suffices for working and the efficiency of working is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spherical surface cutting method and a tool for cutting a spherical surface on a workpiece, and more particularly to improvement of cutting efficiency.

[0002]

2. Description of the Related Art In a spherical surface cutting method, a workpiece and a cutting tool are rotated about axes intersecting each other, and the workpiece and the cutting tool are moved relative to each other in a direction parallel to the tool axis to form a spherical surface. There is a method of cutting. The cutting tool used in this method is one in which a tip having a nose and a horizontal cutting edge and a front cutting edge that respectively linearly extend from the nose is fixed at a position off the tool axis of the tool body. However, in the past, the front cutting edge of the insert was inclined toward the tool axis closer to the nose. Therefore, when cutting the spherical surface on the workpiece by relatively moving the cutting tool and the workpiece in the direction parallel to the tool axis while rotating the cutting tool around the tool axis deviating from the tip, nose and side cutting edge Contacts the workpiece and cuts the spherical surface.

[0003]

However, when cutting is performed by the nose and the horizontal cutting edge of the tip in this way, the nose wears quickly and is frequently ground, or the position of the cutting edge is adjusted by the amount of wear. However, the machining must be frequently interrupted, and there is a problem that the machining efficiency is poor. It is an object of the inventions of claims 1 and 2 to provide a spherical surface cutting method and a spherical surface cutting tool capable of efficiently cutting a spherical surface on a workpiece.

[0004]

In order to solve the above-mentioned problems, the front cutting edge of the tip is brought into contact with a spherical surface along the tangent to the spherical surface in the final stage of cutting work. This is the summary. In order to solve the above-mentioned problems, the invention of claim 2 inclines the front cutting edge of the tip in a direction farther from the tool axis as it approaches the nose, and has the tool body centered on the tool axis. The gist of the present invention is to have a shape that does not interfere with the spherical surface that is in contact with the nose vicinity of the front cutting edge.

[0005]

When a spherical surface is cut on a workpiece by the spherical cutting method according to the first aspect of the present invention, the front cutting edge of the tip contacts along the tangent to the spherical surface at the final stage of the cutting work to finish the spherical surface. To do. When a spherical surface is machined on a workpiece using the spherical surface cutting tool according to the invention of claim 2, the front cutting edge is inclined in a direction farther from the tool axis as it approaches the nose. Cuts into the work piece at the nose and side cutting edge, and in the final stage of processing when most of the predetermined cutting allowance has been cut, the part near the nose of the front cutting edge contacts the spherical surface along the tangent to the spherical surface and finishes . As the spherical surface is cut and the radius becomes smaller, the workpiece and the cutting tool move toward each other, but the tool body has a shape that does not interfere with the spherical surface that contacts the nose vicinity of the front cutting edge. The work piece and the tool body do not interfere with each other, and machining can be performed without any trouble.

[0006]

As described above, according to the invention of claim 1, since the front cutting edge finishes the spherical surface, the position of the front cutting edge needs to be set and maintained with high accuracy. The front cutting edge is less likely to wear as compared to a nose with a small radius of curvature, and it comes into contact at the final stage of cutting, resulting in less wear. Therefore, it is possible to reduce the number of times of polishing and the number of times of adjusting the position of the cutting edge in order to maintain the machining accuracy of the workpiece. Since the cutting process is mainly performed by the nose and the side cutting edge, the amount of wear is relatively large, but the machining accuracy of the workpiece is not determined by the position of the side cutting edge or the nose, so even if these are worn, polishing or grinding There is no need to adjust the position of the cutting edge. Conventionally, the machining accuracy of the work piece is determined by the position of the nose, and because the nose wears a lot, it is necessary to frequently perform polishing and adjusting the position of the cutting edge.
The processing efficiency can be improved.

According to the invention of claim 2, a tool capable of carrying out the method invention of claim 1 is obtained. The tool body has a shape that does not interfere with a spherical surface in contact with the nose portion of the front cutting edge. This is because if the spherical surface of the workpiece is processed in the vicinity of the nose of the front cutting edge, the processing can be performed efficiently. The front cutting edge comes into contact with the spherical surface of the workpiece along the tangent line of the spherical surface, so that the angle formed with the spherical surface is small and cutting resistance is large relative to the amount of material removed by cutting. Therefore, if the machining with the front cutting edge is performed not only in the vicinity of the nose but also in the part away from the nose, the machining efficiency becomes poor. Most of the machining is done by the horizontal cutting edge and the nose, which have a small contact area with the work piece and a small cutting resistance, and the machining by the front cutting edge is done only in the vicinity of the nose in the final stage of machining. The processing can be performed efficiently.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention of claims 1 and 2 will be described in detail below with reference to the drawings.

FIG. 3 shows a workpiece 10 to be spherically cut by the spherical cutting method and tool of this embodiment. The workpiece 10 has a hardness of HRC40.
Made of stainless steel (SICS13), the spherical surface 12, which is the outer peripheral surface of the sphere, is cut out at two locations in parallel with each other to form two side surfaces 14, and these side surfaces 14
A through hole 16 having a center line L _W orthogonal to is formed.

The spherical surface 12 is cut by the spherical cutting tool shown in FIGS. 30 in FIG.
Is the tool body of the spherical cutting tool. This tool body 3
As shown in FIG. 2, 0 has a circular cross-sectional shape, and a plurality of engaging notches 3 opened at the rear end surface and the outer peripheral surface at the rear end portion.
2 are formed at equal angular intervals. The tool body 30 is fitted in the engaging notch 32 with the engaging protrusion of the rotating member that is rotated by a spindle (not shown), and is attached to the rotating member by using a bolt hole 34 formed penetrating in the axial direction. It is fixed with bolts. The rotation torque is transmitted by the engagement between the engagement notch 32 and the engagement protrusion, and the tool body 30 is rotated about the tool axis L _T. The tool body 30 is moved in a direction parallel to the tool axis L _T by a moving device (not shown).

On the tip surface of the tool body 30, the tool axis L _T
Four protrusions 38 are projected at equal angular intervals around
A chip 40 is fixed to each protrusion 38. The tip 40 has a square plate shape as shown in an enlarged view in FIG. 5, and has a rounded nose 42 with a radius of 0.2 mm.
And a horizontal cutting edge 44 extending linearly from the nose 42
And a front cutting edge 46, and a flank 47 is formed as shown in FIG. The chip 40 is fitted into a chip fitting notch 48 formed in the protrusion 38 as shown in FIG. 1, and is fixed by a fixing tool (not shown).

The tip fitting notch 48 is formed substantially in the radial direction of the tool body 30. The shoulder surface 50 of the tip fitting notch 48 is inclined so that the portion closer to the tool axis L _T is located closer to the protruding end of the protrusion 38, and the tip 40 has a front cutting edge 46 closer to the nose 42. The portion is fixed in a state in which it is inclined in a direction farther from the tool axis L _T. Front cutting edge 4
The inclination of 6 is set so that the tip 40 contacts the spherical surface 12 in the vicinity of the nose as shown in FIG. 5 at the final stage of the processing in which the spherical surface 12 has been completely cut by the cutting allowance.

The portion near the nose of the front cutting edge 46 is a value obtained by dividing the distance from the end of the nose 42 by the radius of the spherical surface 12 to be 0.
The position is about 0.1. This value decreases when the radius of the spherical surface is large, and is 0 to 0.01. From the viewpoint that the original purpose is achieved and the machining efficiency is not reduced, it is desirable that the front cutting edge 46 contacts the spherical surface 12 at the boundary with the nose 42, but there is a manufacturing error and the nose 42 is just It is difficult to make contact at the boundary between the two, and when the side cutting edge 44 and the nose 42 are worn, even if the side cutting edge 44 and the nose 42 are re-polished, the front cutting edge 46 is actually in contact with the spherical surface 12. It is desirable to contact the spherical surface 12 at any position within the above range.

In order to clearly show the state in which the front cutting edge 46 is in contact with the spherical surface 12 in FIG. 5, the front cutting edge 46 has a nose 42.
Although illustrated as contacting the spherical surface 12 at a position distant from, the contact is actually made at a position near the end of the nose 42. In addition, the bottom surface 50 of the chip fitting notch 48
The inclination angle of is set to a size that can obtain the inclination angle required for the front cutting edge 46, and the tip 40 is arranged so that the nose 42 is located on the circumference of a radius shorter than the radius of the spherical surface 12 of the workpiece 10. Fixed. Furthermore, the tool body 3 of the protrusion 38
The side surface 52 extending in the circumferential direction of 0 is released from the center of the tool body 30 toward the outer peripheral side.

The tool body 30 is also formed with a recess 54 having a circular cross-section centered on the tool axis L _T and having an opening at the tip end surface thereof. A hole 56 is formed. The recess 54 is
The front cutting edge 46 is formed to have a size that does not interfere with the workpiece 10 when the front cutting edge 46 contacts the spherical surface 12 in the vicinity of the nose.

Next, the cutting process of the spherical surface 12 will be described. At the time of cutting, the workpiece 10 is supported in the through hole 16 by a supporting member (not shown) so as not to rotate relative to it, and the supporting member is rotated by a rotation driving device (not shown) to rotate about the center line L _W. To be At the start of machining, the tool main body 30 is at the retracted end position, and after the workpiece 10 is set, the tool body 30 is advanced toward the workpiece 10 so that the tip 40 moves.
Is cut into the spherical surface 12. During processing, the tool body 3
0 is rotated at 720 rpm and the workpiece 10
Is rotated at one revolution per minute. The spherical surface 12 of the workpiece 10 has a cutting allowance of 3 mm, and the tip 40 has a diameter of 3 mm.
The work piece 10 is cut by division. In addition, the dwell after each cut is 60 seconds.

Roughing and semi-finishing of the spherical surface 12
As shown in FIG. 4, by the nose 42 and the side cutting edge 44, the front cutting edge 46 does not contact the workpiece 10.
The front cutting edge 46 comes into contact with the spherical surface 12 in the vicinity of the nose 42 as shown in FIG.

Since the nose 42 and the side cutting edge 44 rough and semi-finish the spherical surface 12 and the front cutting edge 46 finishes the processing, the front cutting edge 46 performs less processing, and the front cutting edge 46 has the spherical surface 12. Since they come into contact with each other over a wide area, wear is small, and spherical surfaces 12 can be continuously and efficiently cut on a large number of workpieces 10. Since the front cutting edge 46 is less worn and frequent polishing and adjustment of the cutting edge position are not required, the tip 40 is advanced to a preset position for machining, and a large number of workpieces 10 are continuously formed. Can be processed.

If the spherical surface 12 is cut by the tip 40 with the front cutting edge 46 inclined in this way, the error is zero with respect to the diameter of the workpiece 10 even if the cutting is repeated.
It has been confirmed by measurement that the thickness falls within the range of 0.05 mm. This is because when dry cutting is performed on a material whose surface has been processed to remove black skin, when oil is used as the coolant, and when the spherical surface of the black skin material is cut using oil as the coolant. Both have been confirmed.

During cutting, the workpiece 10 is rotated around the center line L _W , and the notched portion of the spherical surface 12 is located on the tool body 30 side as shown by the chain double-dashed line in FIG. However, since the recess 54 is formed in the tool body 30, the workpiece 10 does not interfere with the tool body 30. Tip 40 is spherical 1
The workpiece 10 relatively slightly enters the concave portion 54 as it is cut into 2, but the concave portion 54 does not contact the workpiece 10 even if the nose portion of the front cutting edge 46 of the tip 40 contacts the spherical surface 12. The workpiece 10 does not interfere with the tool body 30 because it has dimensions that do not interfere.

By thus forming the recess 54 in the tool body 30 and avoiding interference with the spherical surface 12, the rigidity of the cutting tool can be increased. Projection 38 for fixing the tip 40
Is long in the tool axis direction, the interference between the spherical surface 12 and the tool body 30 can be avoided. But,
In that case, since the supporting rigidity of the tip 40 by the protrusion 38 becomes low, the concave portion 54 is formed in the tool body 30 to form the spherical surface 1.
It is better to avoid interference with 2.

In the above embodiment, the tool body 30
Was designed to be moved in a direction parallel to the tool axis, the workpiece may be moved, or both the tool body and the workpiece may be moved.

Further, in the above embodiment, every time the tip 40 is cut into the spherical surface 12, the entire surface of the spherical surface is machined by holding it at that position for 60 seconds. Alternatively, the machining may be finished by holding the same position for 60 seconds at the end.

Further, although four chips 40 are provided in the above embodiment, the number is not limited to four, and one or more chips 40 may be provided. However, it is desirable to provide two or more pieces at equal angular intervals in order to balance the cutting resistance.

Further, in the above embodiment, the nose 42 is rounded with a radius of 0.2 mm, but this size can be changed.

Further, it is not essential to rotate the workpiece and the cutting tool around mutually orthogonal axes, and depending on the shape of the workpiece, they may be rotated around axes intersecting at angles other than right angles to cut a spherical surface. You may process.

In addition, the present invention can be carried out in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of drawings]

FIG. 1 is a front view (partial cross section) showing a spherical cutting tool used for carrying out the invention of claim 1, which is an embodiment of the invention of claim 2;

FIG. 2 is a side view of the spherical cutting tool.

FIG. 3 is a front sectional view showing a workpiece whose spherical surface is cut by the spherical cutting tool.

FIG. 4 is a diagram showing the cutting of the tip into the spherical surface at the beginning of cutting the spherical surface by the spherical surface cutting tool.

FIG. 5 is a view showing a state where a front cutting edge of the tip of the spherical surface cutting tool is in contact with a spherical surface.

[Explanation of symbols]

 10 Workpiece 12 Spherical Surface 30 Tool Body 40 Tip 42 Nose 44 Side Cutting Edge 46 Front Cutting Edge 54 Recess

Claims (2)

[Claims] 1. A cutting tool having a tip having a nose and a side cutting edge and a front cutting edge each extending linearly from the nose is rotated about a tool axis deviating from the tip and the workpiece is tooled. In a method of cutting a spherical surface on a work piece by rotating around a work piece axis line intersecting the axis line and relatively moving the cutting tool and the work piece in a direction parallel to the tool axis line, in the final stage of cutting work, the tip 2. The spherical cutting method, wherein the front cutting edge is brought into contact with the spherical surface along a tangent to the spherical surface. 2. A tool body rotatable around a tool axis, a nose and a side cutting edge and a front cutting edge linearly extending from the nose, respectively, and a position off the tool axis of the tool body. In a spherical cutting tool including a tip fixed to, the front cutting edge is inclined in a direction farther from the tool axis as the portion closer to the nose, and the tool body has a center on the tool axis and A spherical cutting tool having a shape that does not interfere with a spherical surface in contact with the nose vicinity of the front cutting edge.