KR20010029191A - Indexable boring tool for cutting an internal surface of a small size's hole - Google Patents

Abstract

PURPOSE: An indexable tool for boring a small hole is provided to improve the accuracy of processing, the surface roughness of processing and cutting ability by rapidly and accurately fixing a cutting insert on an upper face of a holder and to readily replace the cutting insert. CONSTITUTION: An indexable boring tool is comprised of a semi-circular cutting insert(70) prepared with an opening portion(71) in the inside of the center, a settlement portion(72) curved in an arc shape on an upper part of the opening portion and plural cylindrical protruded portions(76) and plural first serrations(90) on a lower face; a cylindrical holder(80) prepared with a V shape groove(84) and plural second serrations(94) on an upper face(81) and a screw inserting hole(82) in the center; and a screw(60) prepared with a head(61) and a support unit(64) and a screw unit(66) integrally formed under the head(61) and inserted in the opening portion and the screw inserting hole. The cutting insert is rapidly separated from and attached to the upper face of the holder by changing the shape of the cutting insert and the upper face of the holder. Further, the cutting insert is firmly fixed on the upper face of the holder. Thus, the accuracy of processing, cutting ability and processed surface roughness are improved.

Description

Indexable boring tool for cutting an internal surface of a small size's hole}

The present invention relates to an indexable boring tool for turning internal diameter machining. More particularly, the cutting insert is fixed on the upper surface of the holder simply, quickly, accurately, and strongly, thereby improving machining accuracy, surface roughness and cutting ability. The present invention relates to an indexable boring tool for turning internal diameters which can be made and the cutting inserts can be easily replaced.

In general, a cutting tool is mainly used for cutting ferrous, nonferrous metals, and nonmetallic materials, and is a tool that is usually mounted on a machine tool to perform cutting to process a workpiece into a desired shape. Typically, such a cutting tool consists of a cutting insert having a cutting edge and a body for holding the cutting insert.

In addition, the cutting tool can be divided into brazing type and indexable type according to the method of fixing the cutting insert to the body, which is permanently fixed by brazing welding the cutting insert to a part of the body. The indexable type is to mount and detach the cutting insert to and from the body using a fixing device provided in the body.

Indexable cutting tools can be easily replaced with new picklings in a short time when the picklings run out of life, a new form that solves the problems of the conventional brazing type cutting tools, ie, the disadvantage of having to regrind the cutting edges for a long time. As a cutting tool of, it is currently used in all parts of cutting tools.

However, indexing requires a clamping mechanism for attaching the insert to a holder or a boring bar, and a space for installing the mechanism must be secured. However, when the space is small, application is difficult. In particular, the cutting tool for internal diameter processing has a limitation in space because the processing is performed in the inner space of the workpiece, and when the workpiece is a small diameter, the space is very narrow, which makes indexing difficult.

On the other hand, there are two ways to cut the metal using a cutting tool, firstly the cutting is performed by contacting the pickled portion of the cutting tool fixed to the rotating metal workpiece. Secondly, the tool with the cutting edge, i.e. the cutting insert, is fixed to the machine tool using the tool holder, and then the workpiece is processed into the desired shape by contacting the fixed workpiece while rotating the cutting tool under such conditions. It is.

Turning is one of the first methods of the metal cutting method, which refers to cutting the workpiece into a desired shape by the linear movement of the cutting tool in the plane including the rotation of the workpiece and its axis of rotation, and transfer of the cutting tool to the workpiece. It is widely used because it can effectively cut various kinds of workpieces according to the movement.

By the way, since the turning tool enters the cutting tool in the axial direction of the workpiece, the boring bar protrusion should be secured from the lathe tool bar, and thus the cutting tool may have an insert breaking property due to vibration caused by the cutting load. Therefore, in the case of internal turning, it is not a problem when the internal diameter of the workpiece is large. However, as the internal diameter decreases, the clamping mechanism is limited, so FGT machining (Forming, Grooving, and Threading) is more powerful than general internal boring. The design is difficult as the clamping mechanism is required and the cutting tool must be smaller due to the space for chip evacuation. As a result, the smallest diameter developed to date is up to φ16, and smaller diameters are using brazing tools or HSS tools.

Recently, a product that can be machined to a minimum working diameter φ8 using a clamping mechanism using screws has been developed by the German company Horn.

4 and 5 show an indexable boring tool developed by the German company Horn. 4 and 5, the conventional indexable boring tool 10 mainly includes a cutting insert 30, a holder 40, and a screw 20 for fixing the cutting insert 30 to the holder 40. do.

The screw insertion hole 41 is formed in the center of the holder 40 according to the prior art, and three fixing grooves 42 are spaced 120 degrees around the screw insertion hole 41 on the upper surface of the holder 40. It is formed radially.

Three protrusions 32 are formed on the lower surface of the cutting insert 30 according to the prior art. The protrusion 32 has a shape corresponding to the shape of the fixing groove 42. A cutout portion 34 protrudes on a radial side of the cutting insert 30, and a screw through hole 31 is formed in the center of the cutting insert 30.

The cutting insert 30 thus formed is fixed on the upper surface of the holder 40 by the screw 20. That is, the screw through-holes 31 and the holders of the cutting inserts 30 aligned in a row with the protrusions 32 formed on the lower surface of the cutting insert 30 positioned in the fixing grooves 42 of the holder 40. The cutting insert 30 is coupled to the holder 40 by inserting the screw 20 into the screw insertion hole 41 of the 40 using a driver (not shown).

The indexable boring tool 10 having such a structure has the advantage of being able to be replaced with a new cutting insert when the cutting portion 32 of the cutting insert 30 wears out and the holder 40 is used. This has the disadvantage that the durability is short and the rigidity of the cutting insert 30 is weak.

In addition, in order to replace the cutting insert 30, the screw 20 must be completely removed from the screw through hole 31 and the screw insertion hole 41 of the holder 40, so that the replacement time is long, and the screw 20 is removed. It is easy to lose it in the removal process, so if the small size screw 20 is mixed with the cutting chip, etc., there is a very difficult problem to find.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to fix the cutting insert on the upper surface of the holder simply, quickly, accurately, and strongly, thereby improving the degree of processing, the surface roughness and The present invention provides an indexable boring tool for turning internal diameters that can improve cutting capability and facilitate cutting exchange of cutting inserts.

1 is an exploded perspective view of an indexable boring tool according to the present invention;

FIG. 2 is an enlarged view of the cutting insert shown in FIG. 1;

Figure 3a is a perspective view of the coupled state of the indexable boring tool shown in Figure 1,

Figure 3b is a cross-sectional view of the coupled boring tool shown in Figure 1,

4 is an exploded perspective view of an indexable boring tool according to the prior art, and

5 is a cross-sectional view of the cutting insert shown in FIG.

<Explanation of symbols for main parts of drawing>

10,50: indexable boring tool 20,60: screw

30,70: cutting insert 34,79: cutout

40,80: holder 41,82: screw insertion hole

61: head 62: wrench insertion portion

64: support portion 66: screw portion

71: opening 73: head seating surface

76: cylindrical projection 77: lower surface

81: holder top surface 83: V groove bottom surface

84: V groove 85: V groove inclined surface

90: first serration 91: first serration end face

92: first serration insertion groove 93: first serration inclined surface

94: second serration 95: second serration inclined plane

96: second serration insertion groove 97: second serration end surface

In order to achieve the above object, the present invention,

The cutting insert has a semicircular shape as a whole, an opening is formed inside the central portion, and a seating portion curved in an arc shape is formed above the opening, and a cutting insert formed by projecting a plurality of cylindrical protrusions and a plurality of first serrations on the bottom surface. ;

A cylindrical holder having a V groove and a plurality of second serrations formed on an upper surface of the cutting insert, and having a screw insertion hole formed at a central portion thereof; And

And a screw inserted into the opening and the screw insertion hole when the cutting insert is fixed to the holder, the head having a wrench insertion portion and a support portion and a screw portion formed integrally with the lower side of the head. Provide indexable boring tools.

As mentioned above, in the indexable boring tool according to the present invention, by changing the shape of the cutting insert and the upper surface of the holder, it is possible to quickly detach the cutting insert on the upper surface of the holder, and to strongly fix, Improved surface roughness and cutting ability.

Hereinafter, an indexable boring tool according to the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view of an indexable boring tool according to the present invention, Figure 2 is an enlarged view of the cutting insert shown in FIG.

1 and 2, the indexable boring tool 50 according to the present invention is mainly a screw for fixing the cutting insert 70, the cylindrical holder 80 and the cutting insert 70 to the holder 80 ( 60).

First, the cutting insert 70 is mainly produced by cementing the cemented carbide material through a powder metallurgy process, that is, a process such as mold pressure, sintering and grinding. The cutting insert 70 has a semicircular shape as a whole, and an opening 71 into which the screw 60 can be inserted is formed inside the central portion. A seating portion 72 curved in an arc shape is formed above the opening portion 71, and a horizontal head seating surface 73 and an inclined chamfer 74 are vertically disposed between the seating portion 72 and the opening portion 71. Are formed in turn.

An exposed surface 75 which is vertically cut at the front position of the opening 71 is formed, and a plurality of cylindrical protrusions 76 are formed at a position near the exposed surface 75 at the lower portion of the cutting insert 70. A portion of the cylindrical protrusion 76 meets at the same height as the end face 91 of the plurality of first serrations 90 formed protruding from the bottom face 77 of the cutting insert 70. In other words, a portion of the cylindrical protrusion 76 is connected to the end face 91 of the first serration 90 protruding from the bottom surface 77 of the cutting insert 70 by the top height of the cylindrical protrusion 76. .

The first serration 90 is to prevent the cutting insert 70 from being rotated by the cutting force during the cutting process using the indexable boring tool 50, and is formed in a cylindrical shape perpendicular to the first serration 90. The protrusion 76 assists the first serration 90 to prevent the cutting insert 70 from rotating by the cutting force during the cutting process using the indexable boring tool 50. A first serration insertion groove 92 having a V shape is formed between the end surfaces 91 of the first serration 90. On both sides of the first serration insertion groove 92, a first serration inclined surface 93 having a predetermined slope is formed, and the first serration inclined surface 93 smoothly meets the first serration end surface 91.

The cylindrical protrusion 76, the bottom face 77 and the first serration 90 smoothly connect with the circular periphery 78 which forms the side of the cutting insert 70. One side of the peripheral portion 78 is formed with a pickled portion (79) protruding. The cutout 79 is formed to protrude in the opposite direction of the exposed surface 75.

Next, a V-groove 84 and a plurality of second serrations 94 are formed in the upper surface 81 of the holder 80 on which the cutting insert 70 is seated. A screw insertion hole 82 is formed at the center of the holder 80 where the V-groove 84 and the second serration 94 cross each other. The screw insertion hole 82 is for accommodating the screw 60 for fixing the cutting insert 70 on the upper surface 81 of the holder 80 and corresponds to the length of the threaded portion 66 of the screw 50. It extends in the vertical direction by the depth.

The V-groove 84 is formed perpendicular to the second serration 94. The V-groove 84 enters a predetermined depth from the upper surface 81 of the holder 80 and extends horizontally. 83) and a V-groove inclined surface 85 which is inclined at an angle between the V-groove bottom surface 83 and the upper surface 81 of the holder 80.

The second serration 94 corresponds to the first serration 90 protruding on the lower surface 77 of the cutting insert 70, and the cutting insert 70 is formed on the upper surface of the holder 80. 81, a second serration inclined surface 95 that meets the inclined surface 93 of the first serration 90, a second serration insertion groove 96 formed between the second serration inclined surface 95, And a second serration end surface 97 that meets the first serration insertion groove 92. In this case, the second serration end surface 97 has a width smaller than the width of the first serration end surface 91.

The head 61 of the screw 60 for fixing the cutting insert 70 to the holder 80 is formed with a star wrench insert 62 into which a wrench (not shown) can be inserted. The support 64 and the threaded portion 66 are integrally formed under the screw head 61. The support portion 64 and the threaded portion 66 extend downwardly from the screw head 61 by a predetermined length. The support 64 is a screw when the screw 60 is inserted into the opening 71 of the cutting insert 70 and the screw insertion hole 82 of the holder 80 to fix the cutting insert 70 to the holder 80. Perform the anti-bending function of (60). The screw portion 66 is a portion to be inserted into the screw insertion hole 82, and consists of a male screw.

FIG. 3A is a perspective view of a coupled state of the indexable boring tool illustrated in FIG. 1, and FIG. 3B is a cross-sectional view of a coupled state of the indexable boring tool illustrated in FIG. 1.

3A and 3B, the cutting insert 70 and the holder 80 of the indexable boring tool 50 configured as described above have the opening 71 of the cutting insert 70 being a screw of the holder 80. With the cutting insert 70 positioned above the holder 80 such that the cutting insert 70 is aligned in the vertical direction with the insertion hole 82, the screw 60 is inserted into the opening 71 and the screw insertion hole 82 using a wrench. The support 64 and the threaded portion 66 are inserted to be integrally coupled.

At this time, the first serration 90 and the cylindrical protrusion 76 of the cutting insert 70 inserted into the second serration insertion groove 96 and the V (V) groove 84 of the holder 80 are mutually different. Since they are located at right angles, the degree of positioning freedom in the left and right directions is large. In addition, the first serration 90 can be rotated about the central axis CL of the cylindrical protrusion 17, and the cylindrical protrusion 17 is in sliding contact with the inclined surface 85 of the V-groove 84. Therefore, the positioning degree is large before the screw 60 is inserted into the opening 71 and the screw insertion hole 82.

Therefore, the first serration 90 and the cylindrical protrusion 76 of the cutting insert 70 are easily assembled into the second serration insertion groove 96 and the V (V) groove 84 of the holder 80. At this time, by tightening the screw 60 using a wrench (not shown), the fastening force is transmitted in the axial direction of the holder 80 so that the first serration 90 and the cylindrical protrusion 76 of the cutting insert 70 The second serration 94 and the V-groove 84 of the holder 80 are completely in contact with each other. In this state, the first serration 90 and the cylindrical protrusion 76 are perpendicular to each other to be in place at a predetermined position. In addition, the center of the first serration 90 of the cutting insert 70 coincides with the center of the second serration 94 of the holder 80 so that both the right hand and the left hand can be interchangeably mounted.

On the other hand, in order to make perfect contact between the cutting insert 70 and the holder 80, the tolerance of the width of the first serration 90 and the cylindrical protrusion 76 should be within 0.03 mm as much as possible. Since the step tolerance of 70) is 2 mm small, the tolerance on the mold can be sufficiently controlled to be 0.03 mm or less.

In addition, when the screw 60 is fastened, the screw head 61 easily contacts the head seating surface 73 (see FIG. 1) of the cutting insert 70 and guides the fastening force to the center portion of the cutting insert 70, thereby effectively clamping. In order to achieve this, the fastening angle θ of the cutting insert 70 was tilted toward the cutting insert 70 by about 0 to 5 degrees. In addition, the screw support 64 is positioned in the screw insertion hole 82 of the holder 80 in order to prevent the bending of the screw 60 due to the reaction force in the A (A) direction.

In addition, the first serration 90 and the cylindrical protrusion 76, which are rotation safety devices, are set toward the lower surface 77 of the cutting insert 70 to maximize the size of the cutting insert 70, and the main component force is concentrated. The lateral thickness t (see FIG. 2) of the cutting insert 70 on the side of the cutout portion 79 acting as a thickened portion was increased to increase rigidity.

As described above, in the indexable boring tool 50 according to the present invention, the insert flesh thickness t on the side of the picked-up portion 79 where the main component force is largely applied is increased, and a plurality of first portions on this portion are also provided. The serration 90 is formed to protrude to increase the anti-rotation effect, and by dispersing the reaction force (insert internal stress) generated by the main component force, it overcomes the conventional limitation that the insert size must be reduced for small hole processing. Rigidity was obtained. Therefore, the indexable boring tool 50 according to the present invention can be powerfully cut.

In addition, the precise setting between the cutting insert 70 and the holder 80, that is, the positioning accuracy is excellent, and the machining precision of the workpiece is improved during cutting, and the small hole makes the vibration caused by the shank hardness of the holder small. Powerful clamping is also available for high speeds, high feeds and high depths of cut, resulting in shorter working times resulting in significant productivity gains. In addition, most of the protrusion of the bottom surface of the cutting insert 70 is inserted into the holder 80 insertion groove to reduce the occurrence of vibration as much as possible to improve the surface roughness and cutting capacity. In addition, the cutting insert 70 can be easily detached even if the screw 60 is loosened by about 1 to 2 rotations, thereby greatly reducing the insert replacement time.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (3)

It has a semi-circular shape as a whole, an opening 71 is formed inside the central portion, and a seating portion 72 curved in an arc shape is formed above the opening 71, and a plurality of cylindrical protrusions are formed on the lower surface 77. A cutting insert 70 formed by protruding the 76 and the plurality of first serrations 90; A V-shaped groove 84 and a plurality of second serrations 94 are formed on the upper surface 81 on which the cutting insert 70 is seated, and a cylindrical holder having a screw insertion hole 82 formed at the center thereof. 80; And A head 61 having a wrench insertion portion 62 formed therein and a support portion 64 and a thread portion 66 integrally formed under the head 61, and the cutting insert 70 is attached to the holder 80. An indexable boring tool comprising a screw (60) inserted into the opening (71) and the screw insertion hole (82) when it is fixed. 2. The cylindrical protrusion (76) of claim 1, wherein the cylindrical protrusion (76) is formed perpendicular to the first serration (90), and a portion of the cylindrical protrusion (76) protrudes by the top height of the cylindrical protrusion (76). It meets the same height as the end surface 91 of the first serration (90), the first serration insertion groove 92 of the V-shape is formed between the end surfaces (91) The first serration inclined surface 93 having a predetermined slope is formed at both sides of the first serration insertion groove 92, and the cylindrical protrusion 76, the lower surface 77, and the first serration ( 90 is an indexable boring tool, characterized in that it is smoothly connected to the circular peripheral portion 78 forming the side portion of the cutting insert (70), the one side of the peripheral portion (78) is formed to protrude. The V-groove 84 is formed perpendicular to the second serration 94 and extends horizontally from the upper surface 81 of the holder 80 by a predetermined depth. V-groove bottom surface 83 and the V-groove bottom surface 83 and the V-groove inclined surface 85 which are inclined at an angle between the upper surface 81 and the upper surface 81. The second serration 94 may include a second serration inclined surface 95 that meets the first serration inclined surface 93 when the cutting insert 70 is placed on the upper surface 81. And a second serration insertion groove 96 formed between the second serration inclined surfaces 95 and a second serration end surface 97 that meets the first serration insertion groove 92. Indexable Boring Tools.