JP2007069278A - Tool gripping chuck and taper shank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chuck which is mounted to a spindle of a machine tool so as to grip a tool, has a short overall length and high rigidity, and is comparatively lightweight and easily handleable. <P>SOLUTION: The tool gripping chuck is provided with a taper shank part 3, in which a plurality of slit grooves 12, 12, etc. suspended while being fitted to a hole of the spindle 2 and upwardly extended from the lower end are formed, a straight chuck tube 4, whose upper end part side is fitted to a hole 6 formed coaxially with the center shaft of the taper shank part 3 and whose lower end part side is downwardly extended, and a roller holding ring 9 in which a plurality of needle rollers 8, 8, etc. to be loosely fitted to the outer periphery of the straight chuck tube 4 are arranged. A fastening nut 5 is fitted to the outer periphery of the roller holding ring 9. A shank 11 of the tool 1 is gripped while being fitted to an internal hole of the straight chuck tube 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chuck for holding a cutting tool such as a drill, and particularly to a chuck that is excellent in rigidity and capable of heavy cutting and is easy to handle.

  The chuck is a device for firmly holding the cutting tool on the spindle of the machine tool, and the cutting tool can be rotated together with the spindle via the chuck. The chuck is required to have a rigidity so that the cutting tool can be gripped accurately and the tool can be stably rotated without cutting during the cutting process. The chuck generally has a large weight and is difficult to mount on the spindle of a machine tool.

  FIG. 4 shows a conventional chuck structure. The chuck of the cutting tool (b) has a holder body (b), and the holder body (b) is a tapered shank portion (d) inserted into a tapered hole provided in the spindle (c) of the machine tool, It has a gripping flange (e) formed at the lower end of the taper shank (d), and extends below the flange (e) in line with the axis of the taper shank (d). A chuck cylinder (f) is provided. Here, the outer peripheral surface of the chuck cylinder (f) is a tapered surface whose diameter decreases toward the lower tip.

  A roller holding ring (g) is loosely fitted on the outer periphery of the chuck cylinder (f), and this roller holding ring (g) faces the tip at a taper angle substantially similar to the taper surface of the chuck cylinder (f). It is formed from a cylinder having a small diameter. The roller retaining ring (g) is held so as not to fall out of the chuck cylinder (f) by a retaining ring provided on the outer periphery of the tip of the chuck cylinder (f).

  The roller holding ring (g) has a large number of needle rollers (h), (h),... Fitted at a predetermined angle in the circumferential direction with respect to the axis of the roller holding ring (g). It is arranged in several stages over the entire surface. Each needle roller (h), (h) is formed with a diameter larger than the wall thickness of the roller retaining ring (g), and thereby protrudes toward the inner peripheral surface side of the roller retaining ring (g). Each needle roller (H), (H), ... that protrudes to the outer peripheral surface side of the roller retaining ring (G) by contacting the rollers (H), (H), ... Is in contact with the inner peripheral surface of the tightening nut (re).

  The clamping nut (re) is a needle roller that reduces the diameter of the chuck cylinder (f) and tightly grips the target tool, and is held by a roller retaining ring (g) on the outer periphery of the chuck cylinder (f). It is fitted via (h), (h). The inner peripheral surface of the tightening nut (re) is configured as a tapered cylindrical surface whose diameter decreases from the end facing the flange (e) toward the tip. In addition, a retaining ring that also serves as a seal is attached to the inner circumference of the base end of the tightening nut (re) on the flange side, and this retaining ring that serves as a seal must abut against the outer peripheral surface of the chuck cylinder (f). The seal function is exerted by this, and by coming into contact with the end face of the roller retaining ring (g), it is prevented from coming off from the chuck of the tightening nut (re).

  In the conventional chuck configured as described above, when the tool (A) is gripped, the spring collet (L) is fitted to the shank (N) of the tool (I) and the tool ( Insert the shank (b) of b) into the cylindrical hole of the chuck cylinder (f). If the tightening nut (re) is rotated clockwise in this state, each needle roller (h) that contacts the tapered cylindrical surface of the tightening nut (re) is slightly inclined. In addition, the roller retaining ring (g) rotates from the lower side of the chuck cylinder (f) to the flange (e) because the outer peripheral surface of the chuck cylinder (f) revolves spirally while rotating in a direction perpendicular to its own axis. As the needle rollers (H), (H),... Revolve, they move while rotating, and at the same time, the tightening nut (R) also moves upward in the direction of the flange (E).

  As a result, the gap between the tapered cylindrical surface of the tightening nut (re) and the outer peripheral tapered surface of the chuck tube (f) is reduced, so that the tightening nut (re) is connected to each needle roller (h), (h) ... The chuck cylinder (f) is pressed from the outer periphery to reduce the diameter. As a result, the shank (nu) of the tool (a) inserted into the cylindrical hole of the chuck cylinder (f) is tightened and gripped via the spring collet (le). If the tightening nut is rotated counterclockwise, the roller retaining ring (g) moves downward toward the tip of the chuck cylinder (f) and the tightening nut (re) moves in the same direction. To do. For this reason, the chuck cylinder (f) whose diameter has been reduced is restored to its original diameter and the gripping force on the tool is released, so that the tool (b) can be removed or replaced.

  By the way, if the tightening nut (re) is rotated, it is moved upward to tighten the chuck cylinder (f) and the spring collet (le) to grip the shank (nu) of the tool (ii). In this case, a gap (e) is left between the upper end of the tightening nut (re) and the flange (e), and the rigidity of the entire chuck decreases due to the existence of the gap (e). As a result, it is difficult to perform heavy cutting with the tool (a).

  Further, the conventional chuck structure has a flange (e) below the tapered shank (d), and further extends a chuck cylinder (f) downward from the flange (e). And, the spring collet (le) fitted with the shank (nu) of the tool (b) is fitted and held in the chuck cylinder (f), but the tapered shank part (d) is fitted. The distance from the spindle (c) of the machine tool is large. This also reduces the rigidity of the chuck and causes chattering during cutting.

On the other hand, a taper shank portion (d), a flange (e), a chuck cylinder (f), and a roller holding ring (g) provided with a needle roller (h) attached to the chuck cylinder (f) In addition, the chuck composed of the tightening nut (re) is heavier, and in a machining center equipped with a large number of tools (b), (b) ... Become. Furthermore, the manufacturing cost of the chuck is very high, and it is not easy to prepare for each tool.
“Chuck” according to JP-A-2005-103730

  As described above, the conventional tool gripping chuck has the above-described problems. The problems to be solved by the present invention are these problems, and provide a tool gripping chuck that is relatively light and easy to handle, has high rigidity, and enables heavy cutting.

  The chuck for gripping a tool according to the present invention has a structure that can be attached to a spindle of a machine tool and grip a tool shank. The chuck for gripping a tool includes a taper shank, a straight chuck cylinder, and It consists of a tightening nut. The tapered shank has a frustoconical shape and has a fitting hole in the central shaft portion. A plurality of slit grooves extending upward from the lower end are formed, and are fitted into and attached to the spindle hole.

  A screw hole is provided above and concentric with the hole of the taper shank, and a screw portion formed at the lower end of the pull stud built in the spindle of the machine tool is screwed into the screw hole and suspended. The upper end of the straight chuck cylinder is fitted and attached to the hole of the taper shank, and the shank of the tool is fitted to the internal hole of the straight chuck cylinder. A roller holding wheel in which a plurality of needle rollers are arranged is fitted on the outer periphery of the straight chuck cylinder, and the tightening nut can be rotated via the needle roller, and the tool fitted in the hole of the straight chuck cylinder is fastened and fixed. The upper surface of the clamping nut is attached in contact with the lower end surface of the spindle.

  The chuck of the present invention has a simple structure comprising a truncated cone-shaped taper shank that fits into a hole in a spindle, a straight chuck cylinder that is fitted and fitted in an inner hole of the taper shank, and a tightening nut that fits on the outer periphery of the lower end of the straight chuck cylinder. Therefore, the weight is about 1/3 that of the conventional one, so that the handling is convenient and the manufacturing cost is reduced to about 1/2.

  The lower end of the straight chuck cylinder that fits into the hole of the taper shank extends downward, and since it does not have a conventional flange, the overall length of the chuck is shortened, and the upper end surface of the clamping nut attached to the straight chuck cylinder Is attached in contact with the lower end surface of the spindle. Therefore, when the chuck is integrated with the spindle, its rigidity is increased and heavy cutting is possible, and chattering does not occur during cutting. Further, since the distance from the spindle to the lower end of the tool is shortened, the space between the workpiece (workpiece) and the tool is enlarged, so that the work becomes easy. On the other hand, the chuck of the present invention has a common taper shank that fits on the spindle, so there is no problem in mounting it on an existing machine tool.

  FIG. 1 is an embodiment showing a tool gripping chuck according to the present invention. In the figure, 1 is a tool, 2 is a spindle of a machine tool, 3 is a taper shank of the chuck, 4 is a straight chuck cylinder, and 5 is a tightening nut. The tapered shank 3 has a truncated cone shape with a thin upper portion, and a straight chuck cylinder 4 extends coaxially below the tapered shank 3.

A hole 6 is provided in the central shaft portion of the taper shank 3, and an upper end portion of the hole 6 is a screw hole 7, and a screw portion formed at a lower end portion of a pull stud built in the spindle 2 is formed. Screwed and suspended. The straight chuck cylinder 4 is fixed by fitting its upper end side into the hole 6 of the taper shank 3, and the lower end part extends downward from the taper shank 3.
The outer peripheral surface of the straight chuck cylinder 4 extending downward from the lower end of the tapered shank 3 is tapered so that the lower diameter is slightly reduced. A roller holding wheel 9 in which a plurality of needle rollers 8, 8... Are arranged is fitted on the outer periphery of the straight chuck cylinder 4, and a tightening nut 5 is fitted on the outer periphery of the roller holding wheel 9.

  The plurality of needle rollers 8, 8... Are inclined at a predetermined angle in the circumferential direction with respect to the axis of the roller holding wheel 9. The roller holding wheel 9 has a slightly smaller diameter on the lower side like the straight chuck cylinder 4. Since the outer diameter of the needle roller 8 is slightly larger than the wall thickness of the roller holding wheel 9, the needle roller 8 is in contact with the outer peripheral surface of the straight chuck cylinder 4 and the inner peripheral surface of the tightening nut 5. The inner peripheral surface of the tightening nut 5 also has a slightly lower diameter.

  A spring collet 10 is fitted inside the straight chuck cylinder 4, and a shank 11 of the tool 1 is fitted inside the spring collet 10. Here, the spring collet 10 is formed with a plurality of slit grooves in the axial direction, and if a tightening force is applied from the outer periphery, the diameter can be reduced and the shank 11 can be gripped.

  FIG. 2 shows a case where the taper shank 3 is fitted and attached to the frustoconical hole of the spindle 2, and a hole 6 is provided in the central shaft portion of the taper shank 3, as shown in FIG. The upper end side of the straight chuck cylinder 4 is fitted. In the taper shank 3, four slit grooves 12, 12,... Extend upward from the lower end, and are thus divided into four shank pieces 13, 13,. .

  If the threaded portion at the lower end of the pull stud is screwed into the screw hole 7 and the tapered shank 3 is suspended and the tapered shank 3 is pulled up, the outer peripheral surface 14 comes into contact with the inner surface of the frustoconical hole, and the groove of the slit groove 12 The width is reduced. The straight chuck cylinder 4 is fixed to the hole 6 by pulling up the taper shank 3 while the straight chuck cylinder 4 is fitted in the hole 6. In this case, the lower end surface 15 of the taper shank 3 is located slightly above the lower end surface 16 of the spindle 2.

  By the way, when the tool 1 is gripped, first, the straight chuck cylinder 4 is removed from the taper shank 3, and the spring collet 10 is fitted to the shank 11 of the tool 1. The shank 11 is inserted into the cylindrical hole of the straight chuck cylinder 4. If the tightening nut 5 is rotated in the clockwise direction in this state, each needle roller 8, 8... That contacts the tapered cylindrical surface of the tightening nut 5 rotates in the direction perpendicular to its own axis while rotating in the chuck cylinder. Since the outer peripheral surface of the roller 4 revolves spirally, the roller holding wheel 9 rises while rotating with the revolution of the needle rollers 8, 8,.

  As a result, the gap between the tapered cylindrical surface of the tightening nut 5 and the outer peripheral tapered surface of the straight chuck cylinder 4 is reduced, so that the tightening nut 5 moves the straight chuck cylinder 4 from the outer periphery via the needle rollers 8, 8. Reduce the diameter by applying strong pressure. As a result, the shank 11 of the tool 1 inserted into the cylindrical hole of the straight chuck cylinder 4 is tightened and gripped via the spring collet 10. If the tightening nut 5 in the tightened state is rotated counterclockwise, the roller holding wheel 9 moves to the lower side of the chuck cylinder 4 and the tightening nut 5 is also lowered in the same direction. For this reason, the chuck cylinder 4 that has been reduced in diameter is restored to its original diameter and the gripping force on the tool is released, so that the tool 1 can be removed or replaced.

  FIG. 3 shows a case where the tool 1 is attached to the straight chuck cylinder 4 via the tightening nut 5. When the tool 1 is attached and fixed to the straight chuck cylinder 4 in this way, the taper shank 3 shown in FIG. The upper end side of the straight chuck cylinder 4 is fitted into the hole 6. At this time, the pull stud on which the taper shank 3 is suspended is lowered, fitted into the hole 6, and the pull stud is raised with the upper end surface 17 of the tightening nut 5 being in contact with the lower end surface 16 of the spindle 2. Pull up the taper shank 3. The outer peripheral surface 14 of the taper shank 3 abuts against the inner peripheral surface of the frustoconical hole of the spindle 2 and the groove width of the slit grooves 12, 12,.

1 shows an embodiment of a tool gripping chuck according to the present invention. The taper shank is attached to the spindle. When a tool is fixed to a straight chuck cylinder via a tightening nut. Conventional chuck for gripping tools.

Explanation of symbols

1 Tool 2 Spindle 3 Tapered Shank 4 Chuck Cylinder 5 Tightening Nut 6 Hole 7 Screw Hole 8 Needle Roller 9 Roller Holding Wheel
10 Spring collet
11 Shank
12 Slit groove
13 Shank pieces
14 Outer surface
15 Bottom edge
16 Bottom edge
17 Top surface

Claims (2)

A chuck attached to a spindle of a machine tool for gripping a tool, wherein a taper shank portion is formed with a plurality of slit grooves extending upward from the lower end of the spindle shank by being fitted in a hole in the spindle, and the taper shank portion. A roller holder in which a straight chuck cylinder is fitted into a hole formed coaxially with the central axis and the lower end side extends downward, and a plurality of needle rollers for loosely fitting on the outer periphery of the straight chuck cylinder are arranged. A gripping tool characterized in that a clamping nut is fitted on the outer periphery of the wheel and the roller holding wheel, and a shank of the tool is fitted into the inner hole of the straight chuck cylinder so that the tool can be gripped. Chuck. In a tapered shank that is attached to the spindle of a machine tool and forms a chuck for gripping a tool, it forms a frustoconical shape and has a hole that fits the upper end of the straight chuck cylinder with the tool on the same axis as the center axis. The upper end portion that is formed with a predetermined length from the lower end and is coaxial with the hole has a screw hole that engages with the screw portion at the lower end of the pull stud built in the spindle, and a plurality of slit grooves extending upward from the lower end. A tapered shank characterized in that the lower end surface of the main shaft is slightly above the lower end surface of the spindle when the main shaft is formed and suspended in a hole of the spindle.

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