JP5752217B2 - Drilling method - Google Patents

Description

  The present invention relates to a hole machining method in which a tool is inserted from the base end side of a through hole to form a large diameter portion in which the diameter of the hole is increased on the distal end side (back side) of the through hole.

  For example, in order to receive the gear and the bearing that rotatably supports the shaft of the gear in the casing of the gear pump, a large diameter portion is formed on both sides of the through hole through which the shaft passes, so that the workpiece is reversed so-called counterbore It is conventionally known to perform machining and boring on both sides. Further, Patent Document 1 describes a cutting tool that inserts an eccentric tool through a through hole by linear motion feed and performs back spot facing. Patent Document 2 describes an undercut drill that attaches a tool to a mounting neck via a cardan joint, tilts the tool at the final stage of drilling, and widens the diameter of the hole at the deepest part of the hole. ing.

Japanese Patent Laid-Open No. 61-065706 Japanese Translation of National Publication No. 01-503615

  If the workpiece is reversed and counterbored or bored on both sides of the through hole, the coaxiality tends to deteriorate when the workpiece is reversed. Therefore, a cutting tool for performing counterbore machining as in Patent Document 1 has been devised.

  However, in the cutting tool disclosed in Patent Document 1, since the tool is inserted straight along the axis of the through hole and the back face is machined, the length of the blade portion perpendicular to the center axis of the tool can be increased. The diameter of the counterbore must be relatively small. On the other hand, in the undercut drill of Patent Document 2, since a cardan joint (universal joint) is used to incline the tool, the rigidity of the tool is low and the machining accuracy is remarkably lowered.

  The present invention has a technical problem to solve such problems of the prior art, and in the machining of a shape in which the diameter of the hole is large on the back side of the through hole, such as a counterbore or a boring hole, the workpiece is not reversed, The object is to provide a hole drilling method that performs highly accurate machining with high efficiency.

In order to achieve the above-described object of the present invention, according to the present invention, at least two linear feed shafts and one rotary feed shaft are provided, and the rotary tool and the workpiece are moved relatively to penetrate the workpiece. In the hole drilling method using a machine tool for machining the back side of the hole, the rotary tool has a shank extending along a central axis, and protrudes in a substantially radial direction with respect to the central axis at the tip of the shank. A blade portion having a cutting edge, and is formed in a substantially L shape. The blade portion is formed by an upper surface forming a rake face and a lower surface opposite to the upper surface. Opening of the through hole as viewed in the direction of the linear feed axis in the direction orthogonal to the central axis of the rotary tool by performing the operations of the two feed axes and the one rotary feed axis a plurality of times or by simultaneous three-axis control Until the height of the part becomes higher than the height of the blade part. Rotating the feed axis, the blade portion of the rotary tool through to the back side of the through hole, hole drilling method to perform processing of the back side of the rotary tool is rotated the through hole is provided.

  According to the present invention, it is possible to process the back side of the through hole with a tool having a blade portion longer than the diameter of the through hole as viewed from the tool side without inverting the workpiece. This makes it possible to perform hole processing with high efficiency and high accuracy.

It is a side view which shows an example of the machine tool for enforcing the drilling method of this invention. It is a side view which shows an example of the rotary tool used with the hole drilling method of this invention. It is a front view of the rotary tool of FIG. 2A. It is a top view which shows an example of the workpiece | work processed with the hole processing method of this invention. It is sectional drawing of the workpiece | work in alignment with arrow BB of FIG. 3A. It is an expanded sectional view of the part shown by circle C in FIG. 3B. It is a figure for demonstrating the hole processing performed to the workpiece | work shown to FIG. 3A-FIG. 3C by the drilling method of this invention using the rotary tool shown to FIG. 2A and 2B. It is a figure for demonstrating the hole processing performed to the workpiece | work shown to FIG. 3A-FIG. 3C by the drilling method of this invention using the rotary tool shown to FIG. 2A and 2B. It is a figure for demonstrating the hole processing performed to the workpiece | work shown to FIG. 3A-FIG. 3C by the drilling method of this invention using the rotary tool shown to FIG. 2A and 2B. It is a figure for demonstrating the hole processing performed to the workpiece | work shown to FIG. 3A-FIG. 3C by the drilling method of this invention using the rotary tool shown to FIG. 2A and 2B. It is a figure for demonstrating the hole processing performed to the workpiece | work shown to FIG. 3A-FIG. 3C by the drilling method of this invention using the rotary tool shown to FIG. 2A and 2B. It is the elements on larger scale which show the state just before introduce | transducing a tool into the through-hole of a workpiece | work. It is a side view of the rotary tool similar to FIG. 2A used when not applying the drilling method of this invention. It is a front view of the rotary tool of FIG. 5A.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
Referring to FIG. 1, an example of a machine tool to which the present invention is applied is shown. 1, a machine tool 10 according to a preferred embodiment of the present invention constitutes a horizontal machining center, and includes a bed 12 as a base fixed to the floor of a factory, and a rear end side of the bed 12 (FIG. 1). Column 14 provided to be movable in the left-right direction or the X-axis direction (direction perpendicular to the paper surface in FIG. 1) on the upper surface on the right side, and provided to be movable in the vertical direction or Y-axis direction on the front surface of the column 14. The head stock 16, the spindle head 18 attached to the head stock 16 and rotatably supporting the main shaft 20, the front-rear direction or the Z-axis direction (left-right direction in FIG. 1) ) Is provided so as to be movable, and a table 22 to which a work 40 is attached via a rotary work head 24 is provided.

  The rotary work head 24 has a work surface for fixing the work 40 on the upper surface, and is fixed to the upper surface of the table 22 on the bottom surface opposite to the work surface. The rotary work head 24 is like a B-axis servo motor (not shown) for rotating and feeding the work surface in the B-axis direction around the vertical axis, and a rotary encoder for detecting the rotational position of the upper surface in the B-axis direction. And a B-axis rotational position sensor (not shown) formed of a rotational sensor.

  The table 22 is provided so as to reciprocate along a pair of Z-axis guide rails (not shown) extending in the horizontal Z-axis direction (left-right direction in FIG. 1) on the upper surface of the bed 12. 12, as a Z-axis feeding device for reciprocating the table 22 along the Z-axis guide rail, a ball screw (not shown) extending in the Z-axis direction and a Z-screw connected to one end of the ball screw. A shaft servomotor (not shown) is provided, and a nut (not shown) that engages with the ball screw is attached to the table 22. The bed 12 is also provided with a Z-axis scale (not shown) that measures the coordinate position of the table 22 in the Z-axis direction.

  The column 14 is provided so as to reciprocate along a pair of X-axis guide rails (not shown) extending in the horizontal X-axis direction (direction perpendicular to the paper surface of FIG. 1) on the upper surface of the bed 12. The bed 12 is connected to a ball screw (not shown) extending in the X-axis direction and one end of the ball screw as an X-axis feeding device for reciprocating the column 14 along the X-axis guide rail. An X-axis servomotor (not shown) is provided, and a nut (not shown) that engages with the ball screw is attached to the column 14. Further, an X-axis scale (not shown) for measuring the coordinate position of the column 14 in the X-axis direction is attached to the bed 12.

  The head stock 16 is provided so as to reciprocate along a pair of Y-axis guide rails extending in the Y-axis direction (vertical direction in FIG. 1) on the front surface of the column 14. The column 14 is connected to a ball screw (not shown) extending in the Y-axis direction and one end of the ball screw as a Y-axis feeding device that reciprocates the headstock 16 along the Y-axis guide rail. A Y-axis servomotor (not shown) is provided, and a nut (not shown) that engages with the ball screw is attached to the headstock 16. Further, a Y-axis scale (not shown) for measuring the coordinate position of the head stock 16 in the Y-axis direction is attached to the column 14.

  The head stock 16 is also provided with a spindle head 18 that supports the spindle 20 so as to be rotatable about a rotation axis O in the Z-axis direction. The spindle head 18 is a spindle rotational position sensor (not shown) comprising a spindle servo motor (not shown) that rotationally drives the spindle 20 and a rotation sensor such as a rotary encoder that detects the rotational position of the spindle 20 around the rotational axis O. Z).

  The X-axis servo motor, Y-axis servo motor, Z-axis servo motor and spindle servo motor, and the X-axis scale, Y-axis scale, Z-axis scale, B-axis rotational position sensor and spindle rotational position sensor are connected to the NC device 26. ing. The NC device 26 controls the power (current value) supplied to each servo motor.

2A and 2B, an example of the tool 30 used in the present embodiment is shown. The tool 30 extends along the central axis O _t , a shank 32 that fits into a tool mounting hole (not shown) of the main shaft 20 or a tool mounting hole of a tool holder (not shown), and a neck 34. The blade portion 36 connected to the tip portion of the shank 32 is provided, and is formed in a substantially L shape as a whole. The blade portion 36 includes an upper surface 36b that forms a rake face, a lower surface 36c opposite to the upper surface 36b, a tip surface 36d that extends between the upper surface 36b and the lower surface 36c, and forms a flank, and an upper surface 36b and a tip surface 36d. The cutting blade 36a is formed between the two. At the proximal end of the blade portion 36, between the neck 34 and the lower surface 36c has a cutout 38 is cut out by the inclined surface which is inclined obliquely to the central axis O _t. The inclined surface forming the notch 38 can be inclined at an angle of 45 ° with respect to the central axis line O _t , for example.

3A to 3C, an example of a workpiece 40 processed by applying the present invention is shown. As an example, the workpiece 40 is a casing of a gear pump, and includes a flat bottom wall 42 and a side wall 44 extending along an outer periphery of the bottom wall 42, and the bottom wall 42 and the side wall 44 define a gear pump gear. A receiving portion 50 for receiving (not shown) is defined and formed so that the tooth tips of the gear are inscribed in the arc portions 44 a and 44 b inside the side wall 44. The bottom wall 42 is formed with first and second through holes 46 and 48 for passing the gear shaft of the gear pump from the inner surface on the receiving portion 50 side of the bottom wall 42 to the outer surface on the opposite side. The central axes O ₁ and O ₂ of the first and second through holes 46 and 48 are disposed on the central axis Ac of the workpiece 40 extending in a direction parallel to the inner surface or the outer surface of the bottom wall 42.

  In particular, referring to FIG. 3C, the first and second through holes 46 (48) include a large diameter portion 46a (48a) that receives a bearing (not shown) for rotationally supporting the shaft of the gear, and the gear. A small-diameter portion 46b (48b) for allowing the shaft to pass therethrough, and an escape portion 46c is formed between the large-diameter portion 46a (48a) and the small-diameter portion 46b (48b). A seal member (not shown) can be disposed in the escape portion 46c. Further, in the design of the gear pump, the central axes of the large-diameter portion 46a (48a), the small-diameter portion 46b (48b), and the arc portion 44a (44b) coincide with each other. Thus, it was difficult to finish, especially finish.

Hereinafter, the operation of the present embodiment will be described.
First, the work 40 is attached to the rotary work head 24 so that the central axes O ₁ and O _{2 of} the first and second through holes 46 and 48 are parallel to the XZ plane of the machine tool 10, and rough. By processing, the inner peripheral surface of the side wall 44 of the workpiece 40, the inner surface of the bottom wall 42, the large diameter portions 46a, 48a and the small diameter portions 46b, 48b of the first and second through holes 46, 48 are formed. In the roughing process, when forming the large diameter portions 46 a and 48 a of the first and second through holes 46 and 48, the workpiece 40 is reversed by rotating the B axis by 180 °, and from the outer surface of the workpiece 40. The large-diameter portions 46a and 48a are processed by spot facing.

Next, the rotary workpiece head 24 rotates and feeds the workpiece 40 in the B-axis direction, the inner surface of the bottom wall 42 of the workpiece 40 faces the tool 30 attached to the tip end of the main shaft 20, and the first and second through holes. The workpiece 40 is oriented so that the central axes O ₁ and O _{2 of} 46 and 48 are parallel to the Z axis. In this state, the tool 30 is replaced with a square end mill for finishing, for example, and the inner peripheral surface of the side wall 44 and the inner surface of the bottom wall 42 of the workpiece 40 are finished.

Next, the tool 30 is replaced with a boring tool for finishing, for example, and the inner peripheral surfaces of the small diameter portions 46b and 48b are finished. In this case, the distance between the center axis O _t of the tool and the cutting edge 36a of the tool 30 coincides with the radius of the finished small diameter portions 46b and 48b. Therefore, the small diameter portion 46b, the tool 30 for 48b processing, have a length corresponding to at least finishing allowance in the radial direction, the center axis O ₁ of the central axis O _t first and second through holes 46, 48 , O ₂ , the blade portion 36 can be easily arranged on the back side (large diameter portion side) through the small diameter portions 46b and 48b.

When finishing of the inner peripheral surfaces of the small diameter portions 46b and 48b is completed, the tool 30 for processing the small diameter portions 46b and 48b is replaced with a tool for finishing the large diameter portions 46a and 48a. The large diameter portion 46a, the tool 30 for 48a processing, the length L _c between the central axis O _t and the cutting edge 36a of the tool, finished machined large diameter portion 46a, coincides with the radius of 48a That is, 1 / 2D ₁ = L _c (D ₁ : diameter of the large diameter portions 46a and 48a).

Further, the large diameter portion 46a, the tool 30 for 48a machining, the diameter of the neck 34 when the d, the length plus the radius of the tool 30 to the length L _c (length of the blade portion) is small When the diameter is larger than the diameter D ₂ of the portions 46b and 48b, that is, D ₂ ≦ 1 / 2d + L _c = 1/2 (d + D ₁ ) (1)
In this case, even if the tool 30 is oriented in the Z-axis direction and moved in the Z-axis direction with respect to the workpiece 40, the blade portion 36 cannot pass through the small diameter portions 46b and 48b. Accordingly, when the difference in radius between the large diameter portions 46a and 48a and the small diameter portions 46b and 48b increases, the tool 30 is moved relative to the workpiece 40 in the Z-axis direction so that the blade portion 36 is passed through the small diameter portions 46b and 48b. In general, as shown in FIG. 5B, the diameter d of the neck 34 must be reduced.

  Even in such a case, according to the hole drilling method of the present invention, which will be described later, even if the diameters of the small diameter portions 46b and 48b and the large diameter portions 46a and 48a satisfy the inequality (1), It is possible to arrange the blade portion 36 on the back side through the small diameter portions 46b and 48b without reducing the diameter d. Hereinafter, the operation of the present embodiment will be further described with reference to FIGS. 4A to 4F. In the following description, only the first through hole 46 will be described, but it will be understood that the same applies to the second through hole 48.

First, the tool 30 is indexed around its central axis O _t and rotationally positioned so that the blade portion 36 is disposed on the second through hole 48 side on the X axis. Next, the tool 30 and the workpiece 40 are relatively moved in the Z-axis and X-axis directions, and the blade portion 36 of the tool 30 is disposed at a position close to the small-diameter portion 46b of the first through hole 46 (FIG. 4A). Next, the second through hole 48 approaches the tool 30 until the central axis O ₁ of the first through hole 46 is at a predetermined angle θ (FIG. 4F) with respect to the central axis O _t of the tool 30 or the Z axis. In this direction, the rotary work head 24 rotates and feeds the work 40 in the B-axis direction. That is, in the hole drilling method according to the present invention, a large diameter portion is finished from the small diameter portion side in a workpiece in which a plurality of through holes having a large diameter portion and a small diameter portion are arranged along a predetermined axis. In this case, the workpiece is rotated and fed in a direction in which the through-holes other than the through-hole to be drilled approach the tool around the predetermined axis and the axis perpendicular to the center axis of the rotary tool. .

As described above, the angle θ at which the workpiece 40 is rotated and fed in the B-axis direction in order to introduce the blade portion 36 of the tool 30 into the small-diameter portion 46b is viewed from the small-diameter portion 46b of the first through hole 46 in the X-axis direction. The opening height H _o is larger than the height H _c of the blade portion 36, and the length of the small diameter portion 46 b in the direction of the central axis O ₁ of the first through hole 46 is L _o. , The angle satisfies the following inequality.
H _c <H _o = D ₂ · sin θ−L _o cos θ (2)

After rotating the workpiece 40 in the B-axis direction, the tool 30 and the workpiece 40 are relatively moved in the Z-axis and X-axis directions, and the blade portion 36 of the tool 30 is introduced into the small diameter portion 46b of the first through hole 46. (FIG. 4B). Next, by simultaneously controlling the X axis, the Z axis, and the B axis, the blade portion 36 of the tool 30 is introduced from the small diameter portion 46b into the large diameter portion 46a (FIG. 4C), and the neck portion 34 is further reduced to the small diameter portion 46b. The tool 30 and the workpiece 40 are relatively moved in an arrangement (FIG. 4D) that can be inserted into the tool. In the steps shown in FIGS. 4C and 4D, by forming the notch 38 in the tool 30, even if the tool 30 having a relatively long length L _c (see FIG. 5) is used, The blade portion 36 can be passed through the large diameter portion 46a.

Further, the blade portion 36 of the tool 30 is disposed outside the large-diameter portion 46a, and the X axis, the Z axis, and the B axis so that the center axis O _t coincides with the center axis O ₁ of the first through hole 46. Are controlled simultaneously (FIG. 4E). Next, the inner peripheral surface of the large-diameter portion 46a is processed by sending the table 22 in the Z-axis direction while rotating the main shaft 20 at a predetermined rotational speed.

The large diameter portion 48a of the second through hole 48 can also be finished in the same manner as the large diameter portion 46a of the first through hole 46. However, when the tool 30 is first rotated and positioned around the central axis O _t , The blade portion 36 is indexed so as to be disposed on the first through hole 46 side on the X axis. In the present embodiment, by indexing the tool 30 in this way, it is possible to avoid the interference between the tool 30 and the side wall 44 of the workpiece 40, and the workpiece 40 can be greatly rotated in the B-axis direction, and θ satisfying the inequality (2) The range can be increased.

  Thus, according to the drilling method according to the present embodiment, the large diameter portion 46a is formed on the surface opposite to the bottom wall 42 of the work 40 as viewed from the tool 30 without rotating the work 40 by 180 ° in the B-axis direction. , 48a can be formed. Of course, the large-diameter portions 46a and 48a can be easily finished by rotating the workpiece 40 180 ° in the B-axis direction and causing the outer surface of the bottom wall 42 to face the tool 30. When the large-diameter portions 46a and 48a are finished, the positional deviation between the central axis of the large-diameter portions 46a and 48a and the central axis of the small-diameter portions 46b and 48b, particularly the positional deviation in the X-axis direction perpendicular to the vertical axis of the B-axis. growing. That is, if the B axis is rotated 180 ° to finish the large diameter portions 46a and 48a, the machining error in the X axis direction is doubled. On the other hand, according to this embodiment, in order to finish the large diameter portions 46a and 48a from the inner surface side of the bottom wall 42 without rotating the workpiece 40 by 180 ° in the B-axis direction, the large diameter portions 46a, The shift between the central axis of 48a and the central axis of the small diameter portions 46b and 48b and the central axis of the arc portions 44a and 44b can be minimized.

DESCRIPTION OF SYMBOLS 10 Machine tool 30 Tool 32 Shank 34 Neck part 36 Blade part 40 Work 46 1st through-hole 46a Large diameter part 46b Small diameter part 48 2nd through hole 48a Large diameter part 48b Small diameter part

Claims (3)

In a hole drilling method using a machine tool that has at least two linear motion feed shafts and one rotary feed shaft, and moves the rotary tool and the workpiece relative to each other to machine the back side of the through hole of the workpiece,
The rotary tool includes a shank (32) extending along a central axis (O _t ) , and a distal end portion of the shank (32) that protrudes in a substantially radial direction with respect to the central axis (O _t ) and has a cutting edge at the distal end portion. And a substantially L-shaped blade portion (36) having
The blade portion (36) is formed by an upper surface (36b) that forms a rake face and a lower surface (36c) opposite to the upper surface, and includes two linear motion feed shafts and one rotary feed shaft. The height (H _o ) of the opening of the through hole as seen in the direction of the linear feed axis in the direction orthogonal to the central axis (O _t ) of the rotary tool by performing the operation a plurality of times or by simultaneous three-axis control Rotating the rotary feed shaft until it becomes higher than the height (H _c ) of the blade portion (36), and passing the blade portion (36) of the rotary tool to the back side of the through hole ,
A hole drilling method comprising: rotating the rotary tool to perform processing on the back side of the through hole. The workpiece is attached to the machine tool such that the axis (O ₁ , O ₂ ) of the through hole is parallel to the plane formed by the two linear feed axes and perpendicular to the axis of the rotary feed axis. The drilling method according to claim 1. The operation of passing the blade part (36) of the rotary tool to the back side of the through hole is performed by first causing the substantially L-shaped tip of the rotary tool to enter the through hole and passing through the through hole. The drilling method according to claim 1 or 2, wherein two linear motion feed shafts and one rotary feed shaft are controlled.

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