JPH0549205U - Holder for boring bar - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a holder for a boring bar which can have a large contact area with the boring bar. [Structure] The holder 20 is formed with a fitting hole 21 for fitting with the shank 8 of the boring bar. The fitting hole 21 is formed as a square hole having a rectangular cross section. Of the inner surface of the fitting hole 21,
The inner surface located on the opposite side in the radial direction of the fitting hole 21 with respect to the opening of the female screw hole 5 is a flat seating surface 21a orthogonal to the axis Y of the female screw hole 5, and a flat surface 9 formed on the shank 8 is formed.
Make surface contact with.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a boring bar holder for mounting a boring bar used for machining the inner diameter of a work material on a tool post of a lathe or the like.

[0002]

[Prior Art]

 As an example of a jig for mounting a boring bar used for machining the inner diameter of a work material on a tool rest of a lathe, a conventional boring bar holder shown in FIGS. 9 to 11 (hereinafter referred to as a holder) is used. Yes. 1 is known. The holder 1 has a substantially cylindrical appearance, and a fitting hole 2 extending along the axis X is formed in the center of the holder in the radial direction, while a tool rest of a lathe (not shown) is formed on a part of the outer circumference. Is formed with a flat surface 3 that comes into contact with the push screw, and a flange 4 that engages with the end surface of the tool rest is formed at one end in the axial direction. Clamp screws 6 are screwed into a plurality (three in the figure) of female screw holes 5 formed by cutting, and these clamp screws 6 are flat on the shank 8 of the boring bar 7 inserted into the fitting hole 2. By contacting the surface 9 and pressing the shank 7 downward, movement of the boring bar 7 in the direction along the axis X and rotation in the circumferential direction are restricted. Then, in this state, the holder 1 is inserted into the center hole of the tool post, and then the flat surface 3 is pressed downward by the push screw of the tool post, whereby the holder 1 is axially and circumferentially moved. The boring bar 7 is held on the tool rest by restraining the movement in the direction. In the figure, reference numeral 10 is a tip removably attached to the tip end side of the boring bar 7, and 11 is a cutting blade formed on the tip 10.

[0003]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional holder 1, since the inner diameter of the fitting hole 2 is set to be slightly larger than that of the shank 8, the tightening of the clamp screw 6 causes the shank 8 and the fitting hole 2 to make a substantially linear contact. When the shank 8 and the fitting hole 2 are in contact with each other, the contact area tends to be small. For this reason, the clamp rigidity of the shank 8 becomes low, chatter vibration is likely to occur, and the distance from the flange 4 to the cutting edge 11 (hereinafter referred to as the protruding length) cannot be made large. In particular, as shown in FIGS. 9 to 11, when the flat surface 9 is also formed on the lower portion of the shank 8, the shank 8 and the fitting hole 2 are formed only at both ends P of the lower flat surface 9. It is even more difficult to secure the rigidity of the clamp because the other parts are not in contact with the fitting hole 2 only by the line contact. Further, since the shank 8 and the fitting hole 2 are in line contact with each other, a large pressure is applied to these contact portions to deform the shank 8 or damage the fitting hole 2. In this regard, as shown in FIG. 11, when the flat surface 9 is also formed on the lower portion of the shank 8, extremely high pressure acts on the contact portions applied to both end portions P of the flat surface 9 to prevent sagging or damage. It is likely to occur. Moreover, as shown in FIG. 11, in the configuration in which the shank 8 contacts the inner wall of the fitting hole 2 at both ends P of the flat surface 9 below the shank 8, the shape error of the flat surface 9 and the dangling of both ends P are caused. Thus, the height of the shank 8 in the direction orthogonal to the flat surface 9 easily changes. If the height of the shank 8 changes, the relative distance between the cutting blade 11 and the holder axis X in the direction orthogonal to the flat surface 9 (hereinafter referred to as the core height) changes accordingly. , The specified processing size and processing accuracy cannot be obtained. The present invention has been made under such a background, the contact area between the shank and the fitting hole can be increased to increase the clamp rigidity, and the shank and the fitting hole can be prevented from being damaged, and An object of the present invention is to provide a holder that can keep the core height constant.

[0004]

[Means for Solving the Problems]

 In order to solve the above problems, the holder of the present invention has a fitting hole that fits with the shank of the boring bar, a female screw hole that reaches the outer peripheral surface of the holder from the inner wall of the fitting hole, and is screwed into the female screw hole. And a flat surface formed on the opposite side of the outer periphery of the shank is pressed by pressing the flat surface formed on the outer periphery of the shank to be inserted into the fitting hole with the clamp screw. In a bowling bar holder adapted to be pressed against the inner wall of a fitting hole, at least a portion of the inner wall of the fitting hole located on the side opposite to the opening of the female screw hole in the radial direction of the fitting hole. A flat seating surface that is orthogonal to the axis of the female screw hole is formed. Here, as the aspect of the fitting hole, only the portion on the opposite side to the opening of the female screw hole is formed on the flat seating surface, and the other portions are formed on the curved surface having a circular cross section as in the conventional case. In addition to the above, the fitting hole as a whole is formed into a square hole having a quadrangular shape in a cross section orthogonal to the holder axis, and one inner surface of the square hole serves as a seating surface. When a plurality of female screw holes are provided, the seating surface is located on the extension of the axial line of the female screw hole, and a plurality of the female screw holes are arranged apart from each other in the axial direction of the fitting hole. An escape portion that recedes toward the radially outer side of the fitting hole may be formed between the surfaces. In particular, in order to easily form the seating surface, it is preferable that the holder be composed of a plurality of blocks that can be divided from each other, and that the fitting hole be formed along the joint surface of these blocks.

[0005]

[Action]

 In the holder having the above structure, since the seating surface of the fitting hole is in surface contact with the flat surface formed on the lower surface side of the shank of the boring bar, the contact area between the shank and the fitting hole is increased. Further, since the seating surface is flat, the shank is always in close contact with the same height, and the core height of the boring bar is always kept constant. Here, if a plurality of seating surfaces are provided and a clearance is formed between them, the seating surface increases the contact area, while the clearance prevents an excessive increase in the contact area. The clamping force does not disperse excessively and the clump rigidity of the shank is maintained at a high level. If the holder is composed of multiple blocks that can be divided and the fitting holes are formed along these joint surfaces, the fitting holes will be located on the joint surface of the block when the blocks are divided. Since it is opened, it is possible to form a flat seating surface in the fitting hole simply by grooving the joint surface when forming the block alone.

[0006]

【Example】

 First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The same components as those of the conventional example shown in FIGS. 9 to 11 described above are designated by the same reference numerals and the description thereof is omitted. Here, in the following description, the side where the flat surface 3 of the holder 20 is formed is treated as the upper portion of the holder 20, and the opposite side is treated as the lower portion.

As shown in FIGS. 1 to 3, the holder 20 of this embodiment is different from the above-described conventional holder 1 in that the fitting hole 21 for fitting the shank 8 of the boring bar 7 is It is a point formed in a square hole having a quadrangular shape in a cross section orthogonal to the axis X of the holder 20. Of the inner surfaces that form the square hole-shaped fitting hole 21, one inner surface 21a located on the opposite side in the radial direction of the fitting hole 21 with respect to the axis Y of the female screw hole 5 is orthogonal to the axis Y. Is a seating surface that can be closely attached to the flat surface 9 on the lower surface side of the shank 8. The distance between the seating surface 21a of the fitting hole 21 and the axis X is such that when the seating surface 21a and the flat surface 9 on the lower surface side of the shank 8 are brought into contact with each other, the cutting edge 11 of the boring bar 7 is It is defined to be at a height equal to the axis X of the holder 20. As the means for forming the fitting hole 21, a well-known machining means such as electric discharge machining is used.

In order to hold the boring bar 7 using the holder 20 having the above-described structure, the shank 8 of the boring bar 7 is inserted into the fitting hole 21 and the shank 8 is held with the flat surface 9 on the lower surface side. After making contact with the seating surface 21a of the fitting hole 21 of the tool 20 and adjusting the protruding length from the flange 4 to the cutting edge 11, the clamp screw 6 mounted in the female screw hole 5 is directed downward. The flat surface 9 on the upper surface side of the shank 8 is screwed in and pressed downward. As a result, the flat surface 9 of the shank 8 and the seating surface 21a of the holder 20 firmly adhere to each other, so that the boring bar 7 is firmly held.

As described above, in this embodiment, since the flat seating surface 21a which is orthogonal to the axis Y of the female screw hole 5 is formed in the fitting hole 21, the flat surface 9 of the shank 8 of the boring bar 7 is fitted to the holder 20. By making surface contact with the dowel 21, the contact area between the shank 8 and the holder 20 is increased as compared with the conventional case. Therefore, the clamping rigidity of the shank 8 is increased, and as a result, chatter vibration is less likely to occur even if the boring bar 7 has a large protruding length. Further, the pressure applied to the shank 8 and the fitting hole 21 is appropriately dispersed according to the increase in the contact area, so that damage to these is prevented. Moreover, since the seating surface 21a is formed on a plane orthogonal to the axis Y of the female screw hole 5, the shank 8 is always in constant contact with the seating surface 21a, and the core height of the boring bar 7 is kept constant. Be done. Therefore, the height of the cutting edge 11 does not change even if sagging occurs at both ends P of the flat surface 9 on the lower surface side of the shank 8.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. The same components as those of the conventional example shown in FIGS. 9 to 11 and the first embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted. As shown in FIGS. 4 and 5, the holder 30 of the present embodiment is wholly constituted by two blocks 32 and 33 which are detachably connected by four bolts 31. The fitting hole 21 similar to that of the above-described first embodiment is formed along the joint surfaces 32a and 33a.

In this embodiment, since the shape of the fitting hole 21 is the same as that of the first embodiment, the same effect can be obtained by increasing the contact area between the shank 8 and the fitting hole 21, and the holder 30 can be used. Since the block itself is composed of two blocks 32 and 33, the upper half and the lower half of the fitting hole 21 are formed on the respective joint surfaces 32a and 33a when the blocks 32 and 33 are individually formed. The fitting hole 21 in the shape of a square hole can be easily obtained only by itself. Moreover, since the upper half or the lower half of the fitting hole 21 is grooved with one end open, it can be easily formed by a general grooved method such as an end mill. In this respect, when the holder 30 is integrally formed, an expensive machining method such as electric discharge machining must be adopted to obtain the square hole. Therefore, according to this embodiment, there is an advantage that the processing cost of the fitting hole 21 can be greatly reduced. In this embodiment, the fitting hole 21 is formed over both the joint surfaces 32a, 33a of the blocks 32, 33, but the fitting hole 21 is formed only on one of the joint surfaces 32a, 33a. It is also possible to form grooves of the same depth and leave the other surface as a flat surface.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. The same components as those of the conventional example and the first and second embodiments described above are designated by the same reference numerals and the description thereof will be omitted. As shown in FIGS. 6 to 8, in the holder 40 of the present embodiment, the seating surface 21 a that abuts the flat surface 9 on the lower surface side of the shank 8 extends into the fitting hole 41 by extending the axis Y of the female screw hole 5. A plurality of relief portions 42 are formed which are spaced from each other in the axial line X direction of the fitting hole 41 while being located on the upper side, and the recesses 42 that recede radially outward are formed between the respective seating surfaces 21a. The shank 8 does not come into contact with the escape portion 42 when the seating surface 21a and the flat surface 9 of the shank 8 are in contact with each other.

According to the holder 40 of the present embodiment, the seating surface 21a of the fitting hole 41 is in close contact with the flat surface 9 on the lower surface side of the shank 8, so that the same as in the first embodiment described above. The effect of is obtained. Moreover, the seating surface 21a is provided only on the extension of the axis Y of the female screw hole 5, and the clearance portion 42 is formed between these seating surfaces 21a to prevent contact with the shank 8, so that the shank 8 is prevented. An excessive increase in the contact area between the flat surface 9 and the fitting hole 41 is prevented, the clamping force of the clamp screw 6 is not excessively dispersed, and the clamping rigidity of the shank 8 is maintained at a high level. By the way, when the seating surface 21a is formed uniformly from one end to the other end of the fitting hole 41 without providing the relief portion 42, the clamping force by the clamp screw 6 is wide over the entire seating surface 21a. Since they are dispersed, the clamp rigidity may deteriorate.

Here, the shapes and dimensions of the holders 20, 30, 40 shown in the first to third embodiments are merely examples, and these may be appropriately changed as necessary. In addition, in each of the embodiments, the cross-sectional shape of the portion including the seating surface 21a of the fitting holes 21 and 41 is square, but the contact area between the shank 8 and the fitting holes 21 and 41 is increased. In order to do so, it is sufficient if at least the flat seating surface 21a is present in the portion located on the opposite side in the radial direction with respect to the openings of the female screw holes 5 into the fitting holes 21, 41, and other portions, For example, the periphery of the opening of the female screw hole 5 may have a circular cross section.

[0015]

[Effect of the device]

 As described above, according to the holder of the present invention, the seating surface of the fitting hole makes a surface contact with the flat surface of the shank of the boring bar to increase the contact area between the shank and the fitting hole. An excellent effect is obtained in that the protruding length of the boring bar can be increased while increasing the rigidity and preventing chatter vibration. In addition, the increase of the contact surface also prevents deformation and damage of the fitting hole and shank. Further, since the seating surface is formed on a plane orthogonal to the axis of the female screw hole, the shank is always in close contact with the seating surface at a constant height, and the core height of the boring bar is kept constant. When a plurality of seating surfaces are provided and a clearance is formed between them, the seating surface increases the contact area, while the clearance prevents the contact area from increasing excessively. Is not excessively dispersed, and there is no fear that the clamp rigidity will be impaired. Furthermore, when the holder is composed of multiple divisible blocks and the fitting holes are formed along these joint surfaces, when forming the block alone, at least one of the blocks has a groove on the joint surface. A flat seating surface can be formed in the fitting hole simply by machining, and it is not necessary to use an expensive machining method such as electric discharge machining to form the seating surface.

[Brief description of drawings]

FIG. 1 is a sectional view of a holder according to a first embodiment of the present invention perpendicular to the axis.

FIG. 2 is an axial sectional view of the holder shown in FIG.

FIG. 3 is an enlarged view showing a central portion of the holder shown in FIG.

FIG. 4 is a sectional view of a holder according to a second embodiment of the present invention perpendicular to the axis.

FIG. 5 is a plan view of a holder according to a second embodiment of the present invention.

FIG. 6 is an axial sectional view of a holder according to a third embodiment of the present invention.

7 is a sectional view taken along line VII-VII in FIG.

8 is a cross-sectional view taken along the line VIII-VIII in FIG.

FIG. 9 is an axial cross-sectional view of a conventional holder.

10 is a cross-sectional view taken along line XX of FIG.

11 is an enlarged view showing a central portion of the holder shown in FIG.

[Explanation of symbols]

 5 Female screw hole 6 Clamp screw 7 Boring bar 8 Shank 9 Flat surface of shank 20, 30, 40 Holding device 21, 41 Fitting hole 21a, 41a Seating surface of fitting hole 32, 33 Block 32a, 33a Block joining surface X Mating hole axis Y Female thread hole axis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Shimizu 1511 Furumagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture Mitsubishi Materials Corporation Tsukuba Works

Claims (4)

[Scope of utility model registration request] 1. A clamp having a fitting hole for fitting with a shank of a boring bar, a female screw hole reaching an outer peripheral surface of a holder from an inner wall of the fitting hole, and a clamp screw screwed into the female screw hole. A boring bar in which a flat surface formed on the outer circumference of the shank to be inserted into the fitting hole is pressed by a screw to press the flat surface formed on the opposite side of the outer circumference of the shank to the inner wall of the fitting hole. In the holder, a flat seat orthogonal to the axis of the female screw hole is formed on at least a portion of the inner wall of the fitting hole that is located on the side opposite to the opening of the female screw hole in the radial direction of the female screw hole. A holder for a boring bar, which is characterized in that a surface is formed. 2. The fitting hole is formed as a square hole having a quadrangular cross section orthogonal to the axis, and one inner surface of the square hole is the seating surface. Holder for boring bar described. 3. A plurality of the female screw holes are provided, and a plurality of the seating surfaces of the fitting holes are arranged apart from each other in the axial direction of the fitting hole while being positioned on an extension of the axis of the female screw hole. The boring bar holder according to claim 1, wherein a clearance portion is formed between each of the seating surfaces so as to recede toward the radially outer side of the fitting hole. 4. The whole structure is composed of a plurality of blocks that can be separated from each other, and the fitting hole is formed along a joint surface of these blocks.
The holder for a boring bar according to any one of 3 above.