JPH04105806A - Collet chuck - Google Patents

Abstract

PURPOSE:To restrain a holder from deforming by the radial stress exerted on the holder tip, also to restrain the deflection of the holder and to make the holder length longer, by making the Young's modulus of the material of the holder larger than that of the material of a collet. CONSTITUTION:In the case of a sintered hard alloy being used for the material of a holder 1 and steel for the material of a collet 2, and the Young's moduli of the both being taken as E1, E2, for example, E1 becomes about three times E2. The deformation of the holder 1 tip by the radial stress exerted as the reaction of the pressing force onto the taper face 4 of the holder 1 from the conical part 5 of the collet 2 is thus prevented, and the holder 1 can be formed in the same outer diameter at its barrel and tip parts. Also the deflection of the holder 1 is in inverse proportion to the Young' s modulus E1, it is restrained to 1/3 in case of being in the same shape, and the length of the holder can be made longer in the case of the deflection being made constant with the holder 1 in the same sectional shape.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention has a proximal end that is pivotally supported by the main shaft of a machine tool, and a rotary tool or workpiece that is calibrated at the distal end, so that these can be attached to the main shaft of a machine tool. This relates to a collet chuck that rotates together with the collet chuck.

[Conventional technology] A chuck is used to pivot a workpiece that cannot be supported by the center of a machine tool, but a collet chuck is especially used when continuously processing thin and long rod-shaped feed. is often used.

This collet chuck generally consists of a cylindrical holder made of steel that serves as the chuck body, a cylindrical collet also made of steel that is inserted into the tip of the inner diameter of this holder, and this collet is pressed toward the proximal end of the holder. It consists of a fixing means for fixing in a tightened state. As this fixing means, for example, a method of drawing the collet with a drawer inserted from the base end of the holder, or a method of pushing the collet with a cap screwed onto the tip of the holder is used.

The tip of the inner diameter of the holder is provided with a taper that increases in diameter toward the tip of the holder, and the tip of the collet also has a circular taper that increases in diameter toward the tip in response to the taper of the inner diameter of the holder. A section has been established. Further, from the distal end of the collet, a sulin I. formed in the radial direction of the collet extends toward the proximal end side.

In such a collet chuck, the end of a bar-shaped workpiece or the proximal end of a rotary tool is inserted into the inner diameter of the collet with a cholera) loaded at the tip of the holder, and the collet is held by the fixing means. When pressed against the proximal end of the holder, the conical portion of the collet tip is pressed against the tapered surface of the inner diameter portion of the holder, causing the collet tip to contract in diameter. As a result, the end of the workpiece inserted into the collet tip and the base end of the rotary tool are calibrated, so the collet is fixed in this state, the base end of the holder is attached to the machine tool spindle, and machining is performed.

[Problems to be Solved by the Invention] However, in such a collet chuck, as a reaction when the conical portion at the tip of the collet is pressed by the inner diameter portion of the holder, the tip portion of the holder is subjected to radially outward stress, that is, It is subject to radial stress. If the holder and the rod are both made of steel as in the conventional example, they have the same rigidity, so if such radial stress acts on the holder over a long period of use, the holder will There is a risk of deformation of the tip or cracking of the tip of the holder. Therefore, in such cholera jacks, the outer diameter of the tip of the holder is generally set larger than the outer diameter of the base and body of the holder to reduce the rigidity of the tip and prevent deformation and cracks. was prevented.

On the other hand, in machining using such a collet chuck, there is also a limit on the length of the chuck. this is,
This is because when machining is carried out with a rotary tool attached to the tip of the jack, the contact resistance between the rotary tool and the workpiece causes the holder to bend around the attachment point of the jack to the machine tool main shaft as a fulcrum. If such a slight deflection occurs, not only will processing accuracy be reduced, but if the deflection exceeds the elastic limit of the holder, the holder may be deformed or damaged.

However, in the cholera 1-type tool, where the outside diameter of the tip is set large and the length is limited, it is difficult to attach a rotary tool to the tip of the shank to process inside holes or grooves. , a problem arises in that the diameter of the hole, the width of the hole, and the depth of the hole or groove that can be machined are limited. In other words, if the hole or groove is smaller than the outer diameter of the holder tip, it is impossible to insert the jack part into the hole or groove and process it, and the depth of the hole or groove is the length of the holder and tool. ”―
Otherwise, the tool will not be able to reach the part to be machined. For this reason, it has been necessary to use other machining means for machining relatively small and deep holes and grooves.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a cylindrical holder, a cylindrical collet inserted into the tip side of the inner diameter part of the holder, In a collet chuck comprising a fixing means for fixing the collet in a pressed state toward the proximal end of the holder, the Young's modulus of the material constituting the holder is El, and the Young's modulus of the material constituting the collet is It is characterized in that when E2 is set, El>E2.

Here, as a combination of the materials constituting the holder and the materials constituting the collet, it is conceivable to use cemented carbide for the holder when steel is conventionally used for the collet.

[Function] In the collet jack having such a configuration, even when the holder is subjected to the above-mentioned radial stress by the collet, the Young's modulus E1 of the material constituting the holder is equal to the Young's modulus E1 of the material constituting the collet.

larger, so that the collet will deform before the holder tip deforms. That is, even if the outer diameter of the tip of the holder is made small, deformation due to radial stress can be suppressed, and the shape of the holder can be formed into a straight shape in which the outer diameter of the body and the tip are the same.

Further, it is known that the deflection of the holder with the proximal end of the holder as the fulcrum is inversely proportional to Young's modulus E when this is approximated as the deflection when a concentrated load is applied to one end of a cantilever. In other words, the Young's modulus E of the material that makes up the polder
The larger the value, the more it is possible to suppress the deflection of the holder even if the outer diameter of the holder is made smaller.

[Embodiment] FIGS. 1 to 4 show an embodiment of the present invention.

In FIGS. 1 and 2, the collet chuck consists of a cylindrical holder 1 that becomes the chuck body, and a cylindrical holder 1 that becomes the chuck body.
The holder 1 is composed of a cylindrical collet 2 that is inserted into the inner diameter end of the holder 1, and a drawbar 3 that fixes the collet 2 in a drawn state toward the base end of the holder 1.

A tapered surface 4 whose diameter increases toward the tip is provided on the tip side of the inner diameter portion of the holder 1 into which the collet 2 is inserted. A conical portion 5 whose diameter increases toward the tip.
is formed.

Furthermore, from the tip of the collet 2, three slits 6 are formed at equal intervals in the circumferential direction of the collet 2 and extend toward the base end. A female threaded portion 7 is provided on the side, and a male threaded portion 8 is provided at the tip of the drawbar 3 to be screwed into the female threaded portion 7 of the collet 2.

In this embodiment, when the Young's modulus of the material constituting the holder l is El, and the Young's modulus of the material constituting the collet 2 is E2, the relationship E>E2 holds between the two.

In this embodiment, the holder 1 is made of cemented carbide, and the collet 2 is made of steel. Note that steel is also used as the material for the drawbar 3.

In order to clamp a workpiece or a rotary tool with a fret chuck having such a configuration, first, as shown in FIG. do. When the drawbar 3 is rotated and the collet 2 is pulled into the proximal end of the holder 1 and fixed, the conical portion 5 at the distal end of the collet 2 is pressed by the tapered surface 4 provided at the distal end of the inner diameter of the holder 1. The tip of the collet 2 divided by the slit 6 is reduced in diameter and engages the base end 9 of a workpiece or rotary tool.

In this way, the collet chuck, which has a workpiece or a rotary tool held at its tip, is attached at its base end to the main shaft of a machine tool, and subjected to rotation about the main shaft for machining.

Here, in the collet chuck of this embodiment, the holder
Cemented carbide is used as the material of collet 2, and steel is used as the material of collet 2, and the Young's moduli of both are El and E, respectively.
Then, the relationship E, > E2 holds true, and more specifically, it is known that El is approximately three times as large as E.

This can prevent the tip of the holder 1 from deforming due to radial stress acting as a reaction to the pressing force from the conical portion 5 of the collet 2 to the tapered surface 4 of the holder 1. This is because, as described above, since the rigidity of the holder 1 is higher than that of the collet 2, the collet 2 itself is deformed by the pressing force before the tip of the holder I is deformed. Therefore, it is possible to make the outer diameter of the tip of the holder l smaller than in the past, and the holder 1 can be made into a holder whose body and tip have the same outer diameter.
It can be molded into a so-called straight shape.

On the other hand, as mentioned above, it is known that the deflection of the holder I is inversely proportional to the Young's modulus E of the Luder 1. In the collet chuck of this embodiment, the cemented carbide forming the holder I has a Young's modulus of approximately 3 compared to conventional steel materials.
Since it is twice as large, if the shape is the same, the holder will bend by 1/3.
can be suppressed to

Conversely, if the amount of deflection is constant with holders having the same cross-sectional shape, the length of the holder can be made longer in this embodiment.

As described above, according to the present invention, even if the outer diameter of the holder is made small, the deformation of the holder tip due to the reaction when suppressing the collet can be suppressed, and even if the length of the holder is made longer, the deformation of the holder tip can be suppressed. Deflection of the holder can be suppressed. These make it possible to form the holder into a thinner and longer straight shape, and it becomes possible to easily process deep holes and grooves with small diameters and widths.

Incidentally, although the cemented carbide that constitutes the holder 1 in this embodiment generally has extremely high rigidity against compressive stress and the like, it tends to lack toughness against bending stress and the like.

However, in the collet chuck in which the collet 2 is drawn in and fixed by the drawbar 3 as in this embodiment, compressive stress is applied to the holder 1 as the axial component of the chuck's pressing force by the collet 2 during calibration. As a result, the holder 1 is compressed in the axial direction. If bending stress is applied in such a state, the holder 1 will be bent after the compressed portion has been restored, and as a result, the toughness against bending will be improved by this compressed amount. .

On the other hand, the drawbar 3 that pulls in the collet 2 is always subjected to tensile and bending stress, but in this embodiment, the drawbar 3 is made of a steel material that is more tough than cemented carbide. It does not deform due to stress.

In this way, in this embodiment, the holder 1 is larger than the holder 1. Even when constructed from an alloy, the holder l can be given sufficient toughness against the bending stress that acts on the collet chuck, and the advantage is that it is possible to prevent the holder l from deforming or breaking due to such stress. have

Next, FIG. 5 and FIG. 6 show another embodiment of the collet portion of the collet chuck of the present invention, and the same parts as in the previous embodiment are given the same reference numerals and the explanation thereof will be omitted.

This embodiment is characterized in that the tip of the inner diameter portion of the collet 11 is set smaller than the collet 2 of the previous embodiment.

With a collet chuck equipped with such a collet II, relatively small-diameter workpieces and the ends of rotary tools can be calibrated more efficiently. Furthermore, by reducing the inner diameter of the collet 11, the wall thickness at the tip of the collet increases.
The rigidity of the collet is increased and the pressing force is increased during calibration.
This has the advantage that deformation of the collet can be suppressed.

Further, FIG. 7 shows another embodiment of the fixing means in the present invention.

In this embodiment, a male threaded portion 22 is threaded on the outer periphery of the tip of the holder 21, and the male threaded portion 22 has a nut provided with an inner edge portion 24 on one end surface that abuts the tip of the collet 23. 25 is screwed into the hole.

According to the collet chuck having such a configuration, when the end portion 26 of the workpiece or rotating tool is loosely inserted into the inner diameter portion of the collet 23 and the nut 25 is screwed, the inner edge portion 24 of the nut 25 comes into contact with the tip portion of the collet 23. When the nut 25 is screwed in, the collet 23 is attached to the holder 21 by the nut 25.
into the proximal end of the Then, the conical portion 28 of the collet 23 is pressed by the tapered surface 27 provided at the tip of the inner diameter portion of the holder 21, and the diameter of the tip of the collet 23 is reduced to calibrate the workpiece or tool.

According to this embodiment, in addition to the advantages of the previous embodiments, the tip of the holder 21 is reinforced in the radial direction by the nut 25, making it possible to further increase the rigidity of the tip of the holder 21. In addition, in this example, the calibration by the collet can be solved simply by operating the tip of the collet chuck, and the workpiece or tool can be replaced while the base end of the collet chuck is attached to the main shaft of the machine tool. It is possible to simplify the process and improve work efficiency.

[Effects of the Invention] As described above, according to the present invention, deformation of the holder tip due to radial stress applied to the holder tip during collet calibration can be suppressed. Furthermore, the holder base can be made larger while keeping the holder from bending.

These make it possible to provide a collet chuck with a thinner and longer straight shape, making it possible to easily process deep holes and grooves with small openings.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, FIG. 1 is a partially cutaway side view of this embodiment, FIG. 2 is a front view of the tip of FIG. 1, FIG. 3 is a partially cutaway side view of the collet of this embodiment, and FIG. 4 is an enlarged view of the tip when a workpiece is calibrated according to this embodiment. 5 and 6 are a partially cutaway side view and a front view of the tip of another embodiment of the collet of the present invention,
FIG. 7 is a partially cutaway side view showing another embodiment of the fixing means of the present invention. 12 Topolder 4.27 Tapered surface, 22...Male thread part, 2 11 2
3 Collet, 5.28 Conical part, 6 Slit, 7 - Female thread part, 3... Drawbar 8 - Male thread part, 25 - Nut. Applicant: Nissin Tool Manufacturing Co., Ltd.

Claims (1)

[Scope of Claims] A cylindrical holder, a cylindrical collet inserted into the distal end of the inner diameter portion of the holder, and a fixing means for fixing the collet in a pressed state toward the proximal end of the holder. In the collet chuck, the Young's modulus of the material constituting the holder is E_1,
A collet chuck characterized in that when the Young's modulus of the material constituting the collet is E_2, E_1>E_2.