JPH0214886Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a chuck for gripping tools such as drills and end mills, and in particular, a chuck tube with a tapered outer peripheral 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.

Conventionally, in this type of chuck, if the wall thickness of the chuck tube is made thinner, the chuck force can be generated more easily and reliably, but the rigidity of the chuck tube decreases and the oscillating motion during cutting is affected. Therefore, there was a problem in that the cutting accuracy deteriorated, and if the wall thickness of the chuck tube was considerably thick, the above-mentioned oscillating motion could be eliminated and the chuck can be maintained, but there was a problem in terms of chuck force.

In addition, for heavy cutting such as milling, the chuck tube requires considerable rigidity, and the component force applied in the axial direction of the milling cutter is excessive, so a strong gripping force (chuck force) is required. Needed.

The present invention solves the conflicting problems mentioned above, and aims to provide a chuck that can make the wall thickness of the chuck tube considerably thicker and that can generate chuck force easily and reliably. To achieve this, the gist of the present invention is to form the chuck tube 4 sufficiently thick, and to form a plurality of hollow portions 5 in the circumferential direction extending in the axial direction from the distal end to the proximal end of the thick chuck tube. It is characterized in that it is arranged in rows with sufficiently thick parts 9 between the cavities, and each cavity 5 is hermetically filled with an incompressible fluid 6 such as oil.

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; It consists of a sufficiently thick-walled chuck tube 4, and the chuck tube serves as a straight shank portion (not shown) of the tool to be gripped.
The chuck tube 4 has a straight inner circumferential surface 4a corresponding to the straight inner circumferential surface 4a and an outer circumferential surface 4b formed in a tapered shape toward the distal end. Hollow portions 5 having a circular cross-section extending in the axial direction are arranged in plural rows in the circumferential direction, and there is a sufficient wall thickness portion 1 between each of the hollow portions 5, 5.
9, each cavity 5 is filled with oil,
An incompressible fluid 6 such as water is hermetically filled. 7
is a tightening rotary tube that is fitted onto the chuck tube 4, and has an inner circumferential surface 7a 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 8 are interposed between the chuck tube 4 and the chuck tube 4 so as to revolve around the outer peripheral surface of the chuck tube 4 in a spiral manner. These needle rollers 8 are held by a retainer 9, and are attached to the tapered outer circumferential surface 4b of the chuck tube 4.
The eight axes of each roller are arranged so as to be appropriately inclined with respect to the generatrix set in 4 is elastically deformed and contracted to grip and hold the tool.

In order to form the cavities 5 in the chuck tube 4 and hermetically fill them with liquid such as oil, for example, the required number of holes as the cavities 5 are drilled from the tip side of the chuck tube 4 with a drill. With these holes filled with oil or the like, a ring-shaped end plate is applied to the distal end surface of the chuck tube 4 and welded together to close the open end of each hole. In FIG. 1, reference numeral 10 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 tightening rotary cylinder 7 is rotated to cause the needle rollers 8 to rotate relative to the outer circumferential surface 4b of the chuck cylinder 4 and run on the chuck cylinder 4 in a spiral direction. The tool is pressed and deformed to reduce its diameter and grip the tool. In this case, the force component in the inward radial direction (indicated by P in FIG. 2) acting on the chuck tube 4 by the needle rollers 8... effectively becomes the gripping force (chuck force); The force component P in the radial direction first presses and deforms the thin wall portion a formed between the outer peripheral surface 4b of the chuck tube 4 and the cavity 5, thereby pressurizing the liquid 6 in the cavity 5. The pressure applied to the liquid 6 in the cavity 5
The chuck tube 4 acts on the thin wall portion b between the chuck tube inner circumferential surface 4a and presses and deforms the thin wall portion b in the inward radial direction, and the diameter of the chuck tube 4 is reduced by the press deformation of the thin wall portion b. ing. As described above, the wall thickness of the chuck tube 4 is quite thick as a whole, but due to the existence of the cavity 5, easily deformable thin parts a and b are formed on both the inside and outside of the cavity 5. The cavity 5 is filled with an incompressible fluid 6, and the pressing force applied to the outer thin wall portion a is transmitted to the inner thin wall portion b through the liquid 6 in the cavity 5, so that the chuck cylinder 4 It is easy to press and deform, and the gripping action can be performed reliably.
Further, the chuck tube 4 has a considerably thick overall wall thickness as described above, and the hollow portion 5 has a thick wall portion 19.
Since they are provided with a sufficient spacing from each other, there is almost no axial runout of the tool during cutting.

It is important to fill the cavity 5 with an incompressible fluid 6 such as oil that does not cause a change in volume. For example, the cavity may be filled with an elastic body such as a soft synthetic resin or a rubber body. is possible, but
If it is an elastic body, the volume will change due to external force, and the pressing deformation of the chuck tube will be absorbed by the elastic body, making it difficult to provide sufficient sliding force.

Moreover, by filling the cavity 5 with the incompressible fluid 6 as in the present invention, the tightening force of the rotary tightening tube 7 is applied not only to the tip side of the chuck tube but also to the rotary tube. Sufficient gripping force can be provided even at the proximal end of the chuck cylinder where the chuck tube 7 does not roll. That is, the tightening force of the rotary tightening tube 7 deforms the thin portion b through the incompressible fluid 6, which exerts a gripping action, but the pressing force of the incompressible fluid 6 is , according to Pascal's principle, not only the hollow part directly below where the rotary cylinder 7 contacts, but also the hollow part near the proximal end of the chuck cylinder (the first
The effect also acts uniformly on the hollow portion in contact with the vicinity of the flange portion 3 in the figure), and as a result, the thin portion b contracts uniformly over the entire area from its tip to its base, and the gripping length in the axial direction increases accordingly. (chuck length) can be increased, and the cutting tool can be gripped more reliably.

Figures 3 and 4 show other embodiments of the present invention, which are completely the same as the embodiments shown in Figures 1 and 2, except that the structure of the cavity is partially different. It is. That is, the chuck main body 11 has a taper shank 12 and a chuck positioning flange portion 13.
It consists of a thick-walled chuck tube 14, and a rotating tightening tube 17 is fitted onto the chuck tube 14 via a needle roller 18.
Further, a plurality of hollow sections 15 each having a circular cross section extending in the axial direction from the distal end to the proximal end are arranged in a plurality of rows in the circumferential direction. It is formed to open at the tip end, and a plastic or metal stopper 15 is liquid-tightly screwed into this open end to close it, and each cavity 15 is filled with oil or the like. liquid 16
is hermetically sealed. The action of this chuck tube 14 is the same as that in the embodiment shown in FIG. 1, so a description thereof will be omitted.

In all of the above-described embodiments, the hollow portion of the chuck tube has a circular cross-section, but the cross-sectional shape of the hollow portion is not limited to circular, but may be any shape such as an ellipse, a polygon, or a rectangle.

As explained above, the chuck of the present invention has a plurality of circumferential rows of cavities extending in the axial direction from the distal end to the proximal end of the chuck tube, and each cavity Since the chuck tube is hermetically filled with an incompressible fluid such as oil, even if the wall thickness of the chuck tube is considerably thick, there is a cavity, and thin-walled parts are formed on both the inside and outside of the cavity. Furthermore, the pressing force applied to the outer thin walled portion by the incompressible fluid within the cavity can be transmitted to the inner thin walled portion through the fluid, and therefore the gripping force, that is, the chuck force, can be easily increased. Since the chuck tube can be made sufficiently thick, the rigidity of the chuck tube can be increased and the oscillating motion during cutting can be eliminated and supported. It is possible to improve cutting accuracy.

In particular, the present invention is characterized in that the cavity is filled with an incompressible fluid that does not cause a change in volume.
It is conceivable to fill the cavity with an elastic body such as rubber other than an incompressible fluid, but such an elastic body changes volume when subjected to external force, and the pressing force applied to the chuck tube is It is difficult to absorb it into the elastic body and provide sufficient gripping force.

However, according to the present invention, since the incompressible fluid filled in the cavity does not change in volume due to external force, the pressing force applied to the chuck tube is applied through the fluid to ensure a sufficient grip. You can demonstrate your power.

Not only that, but the repulsive force of the incompressible fluid in the cavity due to external force acts uniformly over the entire cavity due to Pascal's principle, so that the direct pressing force of the rotating tightening cylinder does not act. By providing the hollow portions up to both ends of the chuck cylinder, the gripping length (chuck length) can be increased, and the cutting tool can be gripped more reliably.

Furthermore, according to the present invention, the chuck tube is formed to have a sufficiently thick wall, and the hollow portions formed in the thick chuck tube are formed at sufficient intervals in the circumferential direction. Because the body itself has sufficient rigidity and strong gripping power,
Even heavy cutting such as milling can be performed safely and accurately.

[Brief explanation of the drawing]

FIG. 1 is a half-longitudinal cross-sectional view showing one embodiment of the chuck according to the present invention, FIG. 2 is a cross-sectional view of the chuck tube in the chuck shown in FIG. 1, and FIG. 3 is another embodiment of the present invention. A longitudinal sectional view similar to FIG. 1 showing
FIG. 4 is a partial end view of the chuck tube as seen from the arrow in FIG. 3. 1...chuck body, 4...chuck tube, 5...
...Cavity portion, 6...Liquid such as oil, 7...Rotary cylinder for tightening, 8...Needle roller.

Claims (1)

[Scope of utility model registration request] A chuck tube with a tapered outer circumferential surface is protruded from the tip side of the chuck body, and a rotating tightening tube having a tapered inner circumferential surface is fitted onto the chuck tube. In a chuck in which a large number of needle rollers are interposed between the tightening rotary cylinder and the chuck cylinder, the chuck cylinder is formed to have a sufficiently thick wall, and the chuck cylinder is formed to have a sufficiently thick wall. A plurality of cavities extending in the axial direction from the distal end to the proximal end of the thick-walled chuck tube are arranged in plural rows in the circumferential direction with a sufficient thickness between the cavities, and each cavity has a sufficient thickness. A chuck characterized by being hermetically filled with an incompressible fluid such as oil.