JPH0121689Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a chuck for gripping tools such as drills and end mills, and in particular, a chuck tube with a tapered outer circumferential surface protrudes from the tip side of the chuck body. A rotary tightening tube having a tapered inner circumferential surface is fitted onto the chuck tube, and between the rotary tightening tube and the chuck tube, there is a gap between the outer circumferential surface of the chuck tube and the chuck tube. This invention relates to a chuck in which a large number of needle rollers that revolve in a spiral are interposed.

In this type of chuck, by providing a plurality of grooves parallel to the axis of the chuck body on the inner circumferential surface of the chuck cylinder, the tool can be gripped in an engaged state in the circumferential direction, and the tool can be firmly gripped. It is known that it can be done. However, in the case of conventional chucks, each groove provided on the inner peripheral surface of the chuck cylinder is open at least at the end on the distal end side of the chuck cylinder, so that the chuck The torsional rigidity of the cylinder decreases, making it weak in terms of strength. Therefore, when cutting is performed while holding a tool such as an end mill, the chuck cylinder may be undesirably deformed due to the cutting load, causing the tool to slip. As I went around, I came across a problem.

Furthermore, recently, cutting tools with oil holes are frequently used, and in this case, oil (cutting oil) is passed from the spindle through the hollow part of the shank to which it is attached, and then the cutting tool is held in the chuck cylinder. Since the oil is supplied to the tool's oil hole, there must be a sealing structure between the chuck tube and the cutting tool held by the chuck tube.

However, if the entire inner circumferential surface of the chuck tube is flat as in the conventional case, this is fine, but if the target is a chuck in which a plurality of grooves are provided in the axial direction on the inner circumferential surface of the chuck tube as in the present invention, The problem is that oil leaks out from these grooves.

The present invention was made in view of the above, and the purpose is to provide a chuck that improves the strength by increasing the torsional rigidity of the chuck tube. Each groove 7 in the inner circumferential surface 4a of the chuck tube extends from the distal end of the chuck tube 4 leaving at least the inner circumferential wall portion to the proximal end of the chuck tube. It is characterized by being closed and having a flat inner circumferential surface 4e at its tip.

Embodiments of the present invention will be described below based on the drawings.

Chuck body 1 of the chuck illustrated in Fig. 1
is a taper shank portion 2 that is removably attached to a spindle head (not shown) of a machining center, etc.
, a chuck positioning flange 3 concentrically connected to the large diameter end of the tapered shank 2; The chuck tube has a straight inner circumferential surface 4a corresponding to a straight shank (not shown) of the tool to be gripped, and an outer circumferential surface tapered toward the tip. 4b.
5 is a rotating tube for tightening that is fitted onto the chuck tube 4;
It has an inner circumferential surface 5a formed in a tapered shape to correspond to the tapered outer circumferential surface 4b of the chuck tube 4,
A large number of needle rollers 6 are interposed between the rotary cylinder 5 and the chuck cylinder 4, and the needle rollers 6 spirally revolve around the outer peripheral surface of the chuck cylinder 4.

On the inner circumferential surface 4a of the chuck tube 4, a plurality of grooves 7 extending parallel to the axis of the chuck body 1 are arranged at equal intervals in the circumferential direction. As is clear from FIGS. 1 and 2, each groove 7 is bored so as to pass through the narrow slit-shaped groove 7a and the middle part of the wall thickness of the chuck tube 4, and communicates with the slit-shaped groove 7a. The slit-shaped groove 7a extends approximately the entire length of the chuck tube 4 from the inner peripheral wall portion 8 at the tip of the chuck tube 4 to the base end of the chuck tube 4. The inner circumferential surface 4e of the tip is flat (flat surface).
It is formed to be. In addition, the circular hole-shaped groove portion 7
A stopper 9 made of rubber, plastic, or metal is fitted into the opening 4c on the tip side of the chuck tube 4b, as shown by the imaginary line in FIG. I am trying to close off the area. Incidentally, the tip surface 4c of the chuck tube 4 has a shallow annular groove 4d along the opening of the circular groove 7b.
are provided around the area.

The needle rollers 6 are held by a retainer 10, and are arranged so that the axial center of each roller 6 is appropriately inclined with respect to the generatrix set on the tapered outer circumferential surface 4b of the chuck cylinder 4. The chuck tube 4 rotates on its axis, revolves in a spiral direction, and rides on the chuck tube 4, thereby causing the chuck tube 4 to elastically deform and contract, thereby gripping the tool.

In FIG. 1, S indicates a stopper for regulating the position of the inner end of the tool inserted into the chuck tube 4.

In the chuck having the above-described structure, the rotary cylinder 5 is rotated in the tightening direction and the chuck cylinder is elastically deformed via the needle rollers 6, and its inner diameter is contracted, so that the tool inserted into the chuck cylinder 4 can be straight-shanked. The plurality of slit-like grooves 7a are engaged with each other in the circumferential direction. In this case, each groove 7 provided in the inner circumferential surface 4a of the chuck cylinder has a narrow slit-shaped groove 7a opening in the inner circumferential surface 4a and a circular hole-shaped groove 7b with a relatively large diameter on the inner side thereof. Therefore, even with a relatively small tightening force by the rotary tightening tube 5, a relatively large amount of elastic deformation can be obtained in the chuck tube 4, and thereby a large gripping force can be obtained. Furthermore, since each groove 7 is formed in the tip 8 of the slit-like groove 7a or in a closed shape, sufficient torsional rigidity is ensured in the chuck tube 4, and strength can be improved. Together with the tip 8, the tip of the arcuate groove 7b is connected to the stopper 9.
Since the inner circumferential surface 4e of the tip portion is formed flat, the cutting tool can be held in a sealed state inside the chuck tube 4.

3 and 4 show another embodiment of the chuck according to the present invention. In this embodiment, the inner circumferential surface 14 of the chuck tube 14 in the chuck body 11 is
The only difference is the structure of the groove 17 provided in section a, and the rest is exactly the same as that illustrated in FIG. 1. That is, on the inner peripheral surface 14a of the chuck tube 14, a plurality of grooves 17 extending parallel to the axis of the chuck body 11 are arranged at equal intervals in the circumferential direction.
As is clear from FIG. 3, each groove 17 extends over almost the entire length of the chuck tube 14 from the distal end 14b of the chuck tube 14 to the proximal end of the chuck tube 14, and when viewed from the side. The shape is a boat bottom shape, and the inner circumferential surface 14 of the tip
The groove 17 is formed flat, and each groove 17 has a narrow overall groove width and is shaped like a slit, as shown in FIG. According to this embodiment, each groove 17 has a slit shape as a whole, and its shape in side view is a ship's bottom shape.
Since the distal end of the groove 17 is closed, the torsional rigidity of the chuck tube 14 is increased and the strength is increased, and the inner circumferential surface 14c of the distal end is flat, so that the distal end of the groove 17 is completely closed. Since the groove 17 is closed, when cooling water or oil is supplied to the tool side through the inside of the chuck body as described above, the water or oil that has entered this groove 17 will not leak to the outside. In FIG. 3, reference numeral 15 indicates a rotating cylinder for tightening, and reference numeral 16 indicates a needle roller.

5 and 6 show still another embodiment of the present invention, in particular, the shape of the groove 27 formed in the inner circumferential surface 24a of the chuck tube 24 of the chuck body 21 is slightly different from that in FIG. The only difference is that everything else is the same. That is, each groove 27
As shown in the figure, the shape in side view is not a boat bottom shape like the embodiment shown in FIG.
c is flat, and this groove 27 is formed with a relatively wide groove width, as is clear from FIG. The third effect of the structure of this embodiment is
Although it is almost the same as the embodiment shown in the figure, this embodiment is relatively easier to process the grooves. In FIG. 5, numeral 25 indicates a rotating cylinder for tightening, and numeral 26 indicates a needle roller.

As explained above, according to the chuck of the present invention, each groove formed on the inner peripheral surface of the chuck cylinder is formed to be thick, leaving at least the inner peripheral wall portion of the tip of the chuck cylinder. Although the contraction action has the effect of reliably gripping the straight shank portion of the tool over its entire length, the torsion of the chuck tube is less than that of a conventional structure with an open groove end. This has the effect of increasing rigidity and improving strength.

Moreover, according to the present invention, not only the tip of the chuck tube is closed, but also the inner circumferential surface of the tip is flat, so even though multiple grooves are provided on the inner circumferential surface of the chuck tube, the inner circumferential surface of the tip is flat. The inside of the chuck tube can be maintained in a sealed state, and oil will not leak from between the chuck tube and the cutting tool held by it.For this reason, it can also be used as a chuck for cutting tools with oil holes. can do.

[Brief explanation of drawings]

FIG. 1 is a half-longitudinal cross-sectional view showing one embodiment of the chuck according to the present invention, FIG. 2 is a partial end view of the chuck tube seen from the arrow in FIG. 1, and FIG. 3 is a diagram showing another embodiment. 4 is a partial end view of the chuck tube seen from the arrow in FIG. 3;
This figure is a half-longitudinal sectional view similar to FIG. 1 showing still another embodiment, and FIG. 6 is a partial end view of the chuck tube as seen from the arrow in FIG. 5. 1, 11, 21...chuck body, 4, 14,
24...chuck tube, 4a, 14a, 24a...
Chuck cylinder inner peripheral surface, 8, 9, 14b, 24b...
Chuck tube tip, 4e, 14c, 24c... Inner peripheral surface of chuck tube tip, 5, 15, 25... Rotating tube for tightening, 6, 16, 26... Needle roller,
7, 17, 27...groove.

Claims (1)

[Scope of utility model registration request] A chuck tube is provided on the tip side of the chuck body and has an inner circumferential surface having a plurality of grooves parallel to the axis of the chuck body and an outer circumferential surface having a tapered shape. A rotary tightening tube having a shaped inner circumferential surface is fitted onto the outside, and a large number of needle rollers that revolve in a spiral with respect to the outer circumferential surface of the chuck tube are arranged between the rotary tightening tube and the chuck tube. In the interposed chuck, each groove on the inner circumferential surface of the chuck tube extends from the distal end of the chuck tube, leaving at least the inner circumferential wall portion, to the proximal end of the chuck tube. A chuck characterized in that the tip is closed and the inner peripheral surface of the tip is flat.