JPH0121690Y2 - - 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.

It is known that this type of chuck has a structure in which a large number of grooves are provided on the inner circumferential surface of the chuck cylinder so that the tool can be gripped in an engaged state by the opening edges of the grooves. The chuck tube has grooves extending in the axial direction of the chuck tube at intervals, and the phase of the grooves in the cross section of the chuck tube is the same over almost the entire length of the chuck tube. The thickness of the part where grooves are provided is thinner over almost the entire length of the chuck tube than the part where the grooves are not carved, and as a result, the bending and torsional rigidity of the chuck tube decreases, making it weaker in terms of strength. When cutting while holding a tool such as an end mill, there is a problem in that the chuck tube is undesirably deformed due to the cutting load.

The present invention was developed in view of the above, and aims to improve the strength by increasing the bending and torsional rigidity of a chuck tube having grooves on its inner circumferential surface. The gist of the present invention is that on the inner circumferential surface 4a of the chuck tube 4,
A plurality of grooves 7 are arranged at equal angular positions in the circumferential direction, and are arranged in a plurality of rows at equal intervals in the axial direction of the chuck cylinder. The groove groups in each row are configured such that the phases of adjacent rows are shifted from each other.

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 4 consists of a straight inner peripheral surface 4a corresponding to a straight shank portion (not shown) of the tool to be gripped, and an outer peripheral surface tapered toward the tip. It has a surface 4b. Reference numeral 5 denotes a tightening rotary tube that is fitted onto the chuck tube 4, and 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 chuck cylinder 4 and the chuck cylinder 4, and the needle rollers 6 revolve helically 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 are arranged at equal angular positions in the circumferential direction and in a plurality of rows at equal intervals in the axial direction of the chuck tube 4. They are arranged in rows like this. That is, as is clear from FIGS. 2 and 3 A and B, four grooves 7 are arranged in the circumferential direction on the inner circumferential surface 4a of the chuck tube 4 at intervals of 90 angular positions. The 7 groups of these 4 grooves are
A total of 44 across 11 rows equally spaced axially as rows.
grooves 7... are provided. Each groove 7 has a longitudinal direction extending along the circumferential direction, a rectangular cross section (see Figure 2), and an arcuate vertical cross section (see Figure 3 A and B). ) is engraved as follows. The 7 groups of 4 grooves in each row arranged in the circumferential direction exhibit the same phase with each other in every other row, and between adjacent rows, it is clear by comparing A and B in FIG. so that the mutual phases are
They are arranged so that they are offset by 45 degrees. In the chuck tube 4 having the grooves 7 arranged in this manner, each groove 7, which is a concave portion of the inner circumferential surface 4a, is discontinuous in the axial direction and the circumferential direction.
Thin wall portions A and thick wall portions B are formed alternately at a constant length in the axial direction over the entire length of the chuck tube 4, and also exist alternately in the circumferential direction.
The bending rigidity and torsional rigidity of the chuck cylinder 4 are increased, and the strength is increased, and the gripping force on the tool can be applied uniformly to the entire outer peripheral surface of the straight shank of the tool.

The needle rollers 6 are held by a retainer 8, 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 tube 4. As a result, the chuck tube 4 rotates on its axis, revolves in a spiral direction, and rides on the chuck tube 4.
It is designed to elastically deform and contract to grip and hold 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 tool inserted into the chuck tube 4 is straightened by rotating the rotary tube 5 in the tightening direction to elastically deform the chuck tube 4 via the needle rollers 6 and contracting its inner diameter. The shank portion is gripped by the opening edge of each of the grooves 7 in an engaged state.

4 and 5A and 5B show modified examples of the chuck tube, which have almost the same structure as the chuck tube 4 illustrated in FIGS. 1 to 3, but the chuck tube 4 has a groove 7. In contrast, the chuck tube 14 shown in FIG. 4 has three grooves 1 arranged in the circumferential direction on its inner peripheral surface 14a.
The difference is that grooves 7 are arranged at intervals of 120 degrees, and these three groups of grooves 17 are arranged in 11 rows in the axial direction, and each row has 3 grooves. The grooves 17 have the same phase in every other row, and have different phases between adjacent rows.
They are arranged so that they are offset by 60°.

As explained above, according to the chuck of the present invention, a plurality of grooves on the inner circumferential surface of the chuck tube are arranged at equal angular positions in the circumferential direction, and a plurality of grooves are arranged at equal intervals in the axial direction of the chuck tube. The grooves are arranged in rows, and the grooves in each row arranged in the circumferential direction are arranged so that the phases of adjacent rows are shifted from each other. The thin and thick portions of the chuck tube are not continuous in the axial direction of the chuck tube as in conventional chucks, but the thin and thick portions are constant over the entire length of the chuck tube. Since the chuck tubes are formed alternately in different lengths and also intermittently in the circumferential direction, it is possible to increase the bending rigidity and torsional rigidity of the chuck tube and improve its strength. Holding force can be applied uniformly to the entire outer peripheral surface of the tool to ensure chuck.

[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 half-longitudinal cross-sectional view showing only the chuck tube of the chuck of FIG. 1, and FIG. 3B is a sectional view taken along line A-A, FIG. 3B is a sectional view taken along line A--A in FIG. FIG. 5B is a sectional view taken along line A and FIG. 1...Chuck body, 4, 14...Chuck cylinder, 4a, 14a...Chuck cylinder inner peripheral surface, 5...
Rotating cylinder for tightening, 6...Needle roller, 7, 17
……groove.

Claims (1)

[Scope of utility model registration request] A chuck tube having a tapered outer circumferential surface is protruded from the tip side of the chuck body, and a rotary tightening tube having a tapered inner circumferential surface is fitted onto the chuck tube, and In a chuck in which a large number of needle rollers are interposed between the tightening rotary cylinder and the chuck cylinder, the needle rollers spirally revolve around the outer peripheral surface of the chuck cylinder. A plurality of grooves are arranged at equal angular positions in the circumferential direction, and are arranged in a plurality of rows at equal intervals in the axial direction of the chuck cylinder, and each row of grooves arranged in the circumferential direction A chuck characterized in that the groove groups are arranged so that the phases of adjacent rows are shifted from each other.