Collet-type tool holder

Abstract

To provide a collet-type tool holder configured so that a cutting tool can be replaced, not from a front side of the tool holder where a cutting edge exists but from a rear side of the tool holder.SOLUTION: A collet-type tool holder, which holds a tool of a machine tool, is provided with: a tool holder main body having a cylindrical sliding part extending in an axial direction of the tool; a collet having a rear taper surface at a rear end part in the axial direction and a front contact surface at a front end part in the axial direction; a sleeve, slidably inserted into the cylindrical sliding part, which has a pressing surface contacting the rear taper surface of the collet; a cap, mounted on the front side of the tool holder main body, which has a pressing surface contacting the front contact surface and has a guide surface to which an outer peripheral surface of the sleeve slidably fits; and sleeve sliding means that makes the sleeve move back and forth in the axial direction, from a rear side of the tool holder main body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a collet-type tool holder used in a machine tool for turning operations such as a lathe, and mainly grips the shank of a cutting tool such as an end mill.

Background Art

[0002] Generally, a machine tool used for turning operations such as a lathe attaches a workpiece via a chuck to the tip of a spindle capable of rotational movement, attaches a cutting tool via a tool holder to a tool post capable of feed movement, and presses the cutting tool against the rotating workpiece to mainly perform machining for cutting out a cylindrical shape.

[0003] Conventionally, as a tool holder that is fixed to a tool post and holds a cutting tool, a collet-type tool holder 100 as shown in FIG. 7 is known.

[0004] Further, Patent Document 1 describes a collet chuck used when attaching a cutting tool such as an end mill to the spindle of a machine tool.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] For a tool holder such as the conventional collet-type tool holder 100 shown in Patent Document 1 and FIG. 7, when performing replacement of a cutting tool, first, the tightening nut 101 is loosened to expand the inner diameter of the collet 102, and a cutting tool (not shown) is extracted. Next, a new cutting tool to be replaced is inserted into the inner diameter of the collet 102, and then the tightening nut 101 is tightened using a working tool such as a wrench. Thereby, the inner diameter of the collet 102 is reduced to grip the shank of the cutting tool and fix the cutting tool. In the tightening operation of this tightening nut 101, it is necessary to apply a strong force to the handle of the working tool.

Summary of the Invention

[0007] Thus, conventional collet-type tool holders are designed to secure cutting tools by tightening a tightening nut near the cutting edge of the cutting tool. Therefore, in lathes and the like equipped with multiple cutting tools as shown in Figure 1, the tightening work must be performed in an area where many cutting edges are present, raising safety concerns such as the risk of touching the cutting edges of other cutting tools. In particular, as shown in Figure 1, when the operator's position is behind the tool post, the operator must reach over the top of the tool post to change cutting tools, making it difficult to tighten the tightening nut using a hand tool.

[0008] Therefore, the present invention has been made in view of the above matters, and aims to provide a collet-type tool holder that allows the tightening of a fastening nut, which requires strong force, to be performed from the rear of the tool holder rather than from the front of the tool holder where the cutting edge of the cutting tool is located, even when changing the cutting tool of a machine tool. [Means for solving the problem]

[0009] This invention was made to achieve the above-mentioned objectives and is characterized by the following:

[0010] The collet-type tool holder according to the present invention is a collet-type tool holder for gripping a tool of a machine tool, comprising: a tool holder body having a cylindrical sliding portion extending in the axial direction of the tool; a collet having a rear tapered surface at its rear end in the axial direction and a front contact surface at its front end in the axial direction; a sleeve slidably inserted into the cylindrical sliding portion and having a pressing surface that contacts the rear tapered surface of the collet; a cap attached to the front of the tool holder body and having a pressing surface that contacts the front contact surface and a guide surface into which the outer circumferential surface of the sleeve slidably fits; and a sleeve sliding means for moving the sleeve back and forth in the axial direction from the rear of the tool holder body. The sleeve sliding means comprises an external threaded portion formed on the sleeve and a clamp nut that screws into the external threaded portion. It is characterized by the following.

[0011] In the collet-type tool holder according to the present invention, it is preferable to provide a cap locking mechanism that tightly secures the cap to the front end surface of the tool holder body.

[0012] In the collet-type tool holder according to the present invention, the cap locking means preferably comprises a locking portion formed on the periphery of the cap and a cap holder that presses against the locking portion.

[0013] In the collet-type tool holder according to the present invention, the cap holder preferably has at least one plunger.

[0014] In the collet-type tool holder according to the present invention, it is preferable that the tool holder body is detachably attached to a body fixing component.

[0015] In the collet-type tool holder according to the present invention, it is preferable that the cap is fixed to the tool holder body by a threaded portion formed on the cap.

[0016] In the collet-type tool holder according to the present invention, a stopper portion is formed on the tool holder body, and it is preferable that the stopper portion abuts against the rear end face of the body fixing component.

[0017] In the collet-type tool holder according to the present invention, it is preferable to provide a rotation-preventing means for preventing rotation of the cylindrical sliding portion of the sleeve around its axis.

[0019] The above summary of the invention does not enumerate all the features necessary for the present invention, and subcombinations of these features may also constitute an invention. [Effects of the Invention]

[0020] According to the collet-type tool holder of the present invention, when replacing the cutting tool, the tightening operation that requires a strong force can be performed from the rear of the safe tool holder instead of in front of the tool holder where the cutting edge of the cutting tool is present. Further, compared with the structure in which the conventional tightening nut is located in front of the tool holder, the distance from the front end face of the tool holder body to the front end face of the cap that holds the collet can be shortened, so that a wider machining range of the workpiece can be secured.

Brief Description of the Drawings

[0021] [Figure 1] A perspective view showing an example of a machine tool to which the collet-type tool holder according to an embodiment of the present invention is attached. [Figure 2] A collet-type tool holder according to a first embodiment of the present invention, where range (a) is a cross-sectional view showing a state where the sleeve is located in the front and the collet is reduced in diameter, and range (b) is a cross-sectional view showing a state where the sleeve is located in the rear and the collet is expanded in diameter. [Figure 3] A collet-type tool holder according to a first embodiment of the present invention, where (a) is a front view showing an unlocked state of the cap, and (b) is a front view showing a locked state of the cap. [Figure 4] A modified example of the collet-type tool holder according to a first embodiment of the present invention, where (a) is a cross-sectional view and (b) is a front view. [Figure 5] A collet-type tool holder according to a second embodiment of the present invention, where range (a) is a cross-sectional view showing a state where the sleeve is located in the front and the collet is reduced in diameter, and range (b) is a cross-sectional view showing a state where the sleeve is located in the rear and the collet is expanded in diameter. [Figure 6] A collet-type tool holder according to a third embodiment of the present invention, where range (a) is a cross-sectional view showing a state where the sleeve is located in the front and the collet is reduced in diameter, and range (b) is a cross-sectional view showing a state where the sleeve is located in the rear and the collet is expanded in diameter. [Figure 7] A cross-sectional view showing a conventional collet-type tool holder.

Modes for Carrying Out the Invention

[0022] Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. Note that the following embodiments are not intended to limit the invention as described in each claim, and not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention.

[0023] Figure 1 is a perspective view showing an example of a machine tool to which a collet-type tool holder according to an embodiment of the present invention is attached. In this specification, "front-rear direction" and "width direction" are defined as the directions and orientations indicated by the arrows in Figure 1.

[0024] The collet-type tool holder 1 according to the present invention grips a cutting tool (a tool in the claims) such as an end mill and is mounted on a tool post 5 provided in a machine tool such as a lathe 2, for example a comb-type lathe, as shown in Figure 1.

[0025] The lathe 2 shown in Figure 1 is equipped with a headstock 3 for rotating the workpiece, and a spindle chuck 4 for fixing the workpiece is attached to the tip of the headstock 3. Opposite the headstock 3 is a tool post 5 equipped with multiple collet-type tool holders 1.

[0026] Such a lathe 2 uses the rotation of the headstock 3 to which the workpiece is mounted as the main motion for cutting or grinding, and the linear motion in the front-rear and width directions of the tool post 5 to which the collet-type tool holder 1 according to the present invention is mounted as the feed motion, and is mainly used to machine cylindrical products.

[0027] Furthermore, the position from which the operator operates the lathe 2 or performs tasks such as changing cutting tools is located behind the tool post 5.

[0028] In this embodiment, the collet-type tool holder 1 has been described in the case where it is attached to a comb-type lathe capable of mounting multiple cutting tools. However, the machine tool in which the collet-type tool holder 1 according to the present invention is used is not limited to this, and may be other machine tools such as general-purpose lathes.

[0029] [First Embodiment] Figure 2 shows a collet-type tool holder according to the first embodiment of the present invention, where range (a) is a cross-sectional view showing the state in which the sleeve is positioned forward and the collet is reduced in diameter, and range (b) is a cross-sectional view showing the state in which the sleeve is positioned rearward and the collet is expanded in diameter. Figure 3 shows a collet-type tool holder according to the first embodiment of the present invention, where (a) is a front view showing the unlocked state of the cap, and (b) is a front view showing the locked state of the cap. In this embodiment, "front-rear direction" is defined as the direction and orientation shown in Figure 1. Also, "width direction" is defined as the direction shown by the arrows in Figures 3(a) and (b).

[0030] As shown in Figure 2, the collet-type tool holder 1 according to this embodiment comprises a tool holder body 10 attached to a tool post 5, a sleeve 20 inserted into the tool holder body 10, and a collet 30 inserted into the front end of the sleeve 20 and gripping a cutting tool (not shown). The collet-type tool holder 1 also comprises a cap 40 that abuts against the front end of the collet 30 and prevents the collet 30 from moving forward, and a cap holder 50 that serves as a cap locking means for fixing the cap 40. The collet-type tool holder 1 also comprises a clamp nut 60 located behind the sleeve 20 and serving as a sleeve sliding means for moving the sleeve 20 in the front-rear direction.

[0031] As shown in Figures 2 and 3(a), the tool holder body 10 is a rectangular parallelepiped component and includes a cylindrical sliding portion 11 that allows the sleeve 20 to be inserted at a position that matches the height of the spindle of the headstock 3. A guide portion 12 that fits into a groove formed in the tool post 5 is attached to the bottom surface of the tool holder body 10. The guide portion 12 is a component with a substantially rectangular cross-section and is attached so as to extend in the width direction of the tool holder body 10. The mounting position of the tool holder body 10 in the front-rear direction relative to the tool post 5 is determined by the guide portion 12. In addition, the tool holder body 10 is fixed to the tool post 5 by bolts that pass through the tool holder body 10 vertically, as shown in Figure 3(b) as an example.

[0032] As shown in Figure 2, the cylindrical sliding portion 11 consists of a through hole extending in the axial direction of the cutting tool. The cylindrical sliding portion 11 is formed to provide a predetermined clearance with the outer circumferential surface 21 of the sleeve 20 so that the sleeve 20 can slide properly. Furthermore, since the clearance between the cylindrical inner surface of the cylindrical sliding portion 11 and the outer circumferential surface 21 of the sleeve 20 affects the positional accuracy of the cutting tool attached to the collet-type tool holder 1, it is preferable to set it to be appropriately small. In addition, it is preferable that the cylindrical inner surface of the cylindrical sliding portion 11 be finished to a smooth surface so that the sleeve 20 can slide smoothly.

[0033] Furthermore, it is preferable that the cylindrical sliding portion 11 is provided with a rotation-preventing mechanism to prevent rotation of the sleeve 20 around its axis. As an example, the rotation-preventing mechanism consists of a key 13 and a key groove formed on the cylindrical sliding portion 11 and the outer circumferential surface 21 of the sleeve 20, respectively, corresponding to the key 13, as shown in Figure 2.

[0034] As shown in Figure 2, the sleeve 20 is a substantially cylindrical component, and as described above, its outer circumferential surface 21 abuts against the cylindrical inner surface of the cylindrical sliding portion 11 and slides in the front-rear direction within the cylindrical sliding portion 11. Therefore, it is preferable that the outer circumferential surface 21 be finished to a smooth surface so that the sleeve 20 can slide smoothly. Behind the outer circumferential surface 21, as shown in Figure 2, an outer diameter threaded portion 22 is formed that screws into the inner diameter threaded portion 61 of the clamp nut 60. The shank of a cutting tool (not shown) is inserted inside the sleeve 20. Therefore, the inner diameter of the sleeve 20 is formed to be larger than the outer diameter of the shank so as not to interfere with the shank of the cutting tool. A pressing surface 23 that abuts against the collet 30 is formed on the cylindrical inner surface of the front end of the sleeve 20. The pressing surface 23 is formed as a tapered surface that widens toward the front end face of the sleeve 20.

[0035] As shown in Figure 2, the collet 30 is a substantially cylindrical part, with a rear tapered surface 31 that tapers toward the rear end face on the outer circumferential surface of the rear end, a front contact surface 32 that tapers toward the front end face on the outer circumferential surface of the front end, and an annular groove 33 formed between the rear tapered surface 31 and the front contact surface 32. The rear tapered surface 31 contacts the pressing surface 23 of the sleeve 20 and is formed as a tapered surface at an angle corresponding to the pressing surface 23. Inside the collet 30, a tool insertion hole 34 is formed for inserting the shank of a cutting tool (not shown). The tool insertion hole 34 is normally in an expanded state, allowing for easy insertion of the shank of a cutting tool. In addition, the collet 30 has multiple slits (not shown) that extend in the axial direction. Although the front contact surface 32 has been described as a so-called tapered surface that tapers toward the front end face, the shape of the front contact surface 32 is not limited to this, and for example, it may be formed as a plane perpendicular to the axial direction of the collet 30.

[0036] As shown in Figure 2, the cap 40 is a substantially cylindrical component. The inner surface of the rear end of the cap 40 has a guide surface 41 that slides against the outer circumferential surface 21 of the sleeve 20, and the inner surface of the front end has a retaining surface 42 that tapers toward the front end surface. Between the guide surface 41 and the retaining surface 42, an engaging rib 43 is formed that engages with the annular groove 33 of the collet 30. As shown in Figure 3(a), a pair of locking portions 44 are formed on the outer circumferential surface of the cap 40, extending radially outward and spaced apart from each other. At least one engaging rib 43 is formed, but multiple ribs may be formed.

[0037] The guide surface 41 determines the radial position of the cap 40 when the sleeve 20 is inserted. The guide surface 41 is formed to have a predetermined clearance with the outer circumferential surface 21 of the sleeve 20 so that it can slide properly against the outer circumferential surface 21 of the sleeve 20. Furthermore, the clearance between the guide surface 41 and the outer circumferential surface 21 of the sleeve 20 determines the coaxiality between the pressing surface 23 of the sleeve 20 and the retaining surface 42 of the cap 40, and therefore affects the positional accuracy of the cutting tool attached to the collet 30. For this reason, it is preferable that the clearance between the guide surface 41 and the outer circumferential surface 21 of the sleeve 20 be set to be appropriately small. In addition, it is preferable that the guide surface 41 be finished to a smooth surface so that it can slide smoothly against the outer circumferential surface 21 of the sleeve 20.

[0038] The retaining surface 42 contacts the front contact surface 32 of the collet 30 and is formed as a tapered surface that decreases in diameter towards the front end face, corresponding to the shape of the front contact surface 32. The retaining surface 42, together with the pressing surface 23 of the sleeve 20, affects the positional accuracy of the cutting tool attached to the collet 30. Therefore, it is preferable that the coaxiality between the retaining surface 42 and the guide surface 41 that slides on the outer peripheral surface 21 of the sleeve 20 be set appropriately and strictly.

[0039] Although the pressing surface 42 was described as a tapered surface that narrows in diameter towards the front end face, the shape of the pressing surface 42 is not limited to this. For example, if the front contact surface 32 of the collet 30 is formed on a plane perpendicular to the axial direction of the collet 30, the pressing surface 42 may also be formed on a plane perpendicular to the axial direction of the cap 40 to match.

[0040] As shown in Figure 3(a), the locking portion 44 is formed as a pair of pieces having a predetermined width and spaced apart from each other radially outward. As shown in Figure 3(b), when the cap 40 is locked, the locking portion 44 receives a rearward load from the plunger 53, which will be described later. When the cap 40 is locked and the sleeve 20 is positioned rearward and the collet 30 is expanded in diameter, as shown in area (b) of Figure 2, the rear end face of the locking portion 44 contacts the front end face of the tool holder body 10. Also, when the cap 40 is locked and the sleeve 20 is positioned forward and the collet 30 is contracted in diameter, as shown in area (a) of Figure 2, the front end face of the locking portion 44 contacts the stepped portion 52 of the cap holder 50, which will be described later. Therefore, the surface accuracy of the front and rear end faces of the locking portion 44 affects the gripping accuracy of the cutting tool. Therefore, it is preferable that the front and rear end faces of the locking portion 44 are formed with good perpendicularity to the axis of the guide surface 41, and with good perpendicularity to the axis of the tapered pressing surface 42 or parallelism to the planar pressing surface 42.

[0041] As shown in Figure 3(a), the cap holder 50 is a pair of parts that are located above and below the cap 40 and are attached separately. As shown in Figure 2, the cap holder 50 has a stepped portion 52 that forms a gap 51 between it and the front end face of the tool holder body 10. As shown in Figure 3(b), the locking portion 44 of the cap 40 is inserted into the gap 51 when the cap 40 is locked. In addition, at least one plunger 53 is attached to each of the upper and lower cap holders 50 in the stepped portion 52.

[0042] The plunger 53, for example, has a ball or pin at its tip and a spring inside its body. When a load is applied to the tip of the plunger 53, the ball or pin is pushed into the body, and when the load is removed, the ball or pin returns to its original position due to the spring.

[0043] To fix the cap 40 using such a cap holder 50, first, as shown in Figure 3(a), the cap holder 50 is positioned so that the locking portion 44 of the cap 40 is located between the upper and lower sections of the cap holder 50, and the rear end face of the locking portion 44 is brought into contact with the front end face of the tool holder body 10. Next, as shown in Figure 3(b), the cap 40 is rotated to insert the locking portion 44 into the gap 51. At this time, the tip of the plunger 53 is pushed into the plunger 53 by the front end face of the locking portion 44, and the spring of the plunger 53 exerts elastic force. A spring load is applied to the locking portion 44 via the tip of the plunger 53, and the cap 40 is pressed against the tool holder body 10, fixing its position in the rotational direction. With a cap holder 50 having such a cap locking mechanism, the cap 40 can be easily fixed to the tool holder body 10. Furthermore, when fixing the cap 40, a recess may be provided on the end face of the locking portion 44, which corresponds to the tip of the plunger 53. Such a recess on the end face of the locking portion 44 ensures that the cap 40 is securely fixed in the rotational direction.

[0044] Furthermore, with this type of cap holder 50, the structure that holds the collet 30 can be made shorter in the longitudinal direction compared to a conventional tool holder 100 having a tightening nut 101 as shown in Figure 7. As a result, the distance from the front end face of the tool holder body 10 to the front end face of the cap 40 is shortened, making it possible to secure a wider space for machining the workpiece.

[0045] In this embodiment, the cap holder 50 has been described as a pair of parts that are attached separately, one above the other. However, the configuration of the cap holder 50 is not limited to this; it may be a single, integrated part, or a part that is divided into two or more parts. Similarly, the locking portion 44 has been described as a pair of pieces that are spaced apart from each other radially outward. However, it is not limited to this and may be set appropriately according to the configuration of the cap holder 50. Furthermore, in this embodiment, the plunger 53 has been described as being attached to the stepped portion 52 of the cap holder 50. However, the position of the plunger 53 is not limited to this; it may also be attached to the front end face of the tool holder body 10 with its tip facing forward. In this case, the cap 40 is pressed against the cap holder 50, fixing its position in the rotational direction.

[0046] As shown in Figure 2, the clamp nut 60 is a substantially cylindrical component that is rotatably attached to the rear of the tool holder body 10 via a clamp nut retaining component 62. The sleeve 20 passes through the inside of the clamp nut 60, and an internal threaded portion 61 is formed on the inner circumferential surface of the front end, which engages with the external threaded portion 22 of the sleeve 20. The outer circumferential surface of the rear end of the clamp nut 60 has a hexagonal surface (not shown) that can be gripped by a work tool such as a wrench, and a groove (not shown) for hooking a work tool.

[0047] The clamp nut retaining component 62 is attached to the rear end face of the tool holder body 10 by a bolt or the like (not shown). The clamp nut retaining component 62 rotatably supports the clamp nut 60 and prevents the clamp nut 60 from retracting from the tool holder body 10. As shown in Figure 2, the clamp nut retaining component 62 is attached so as to form a gap between it and the rear end face of the tool holder body 10. However, the method of attaching the clamp nut retaining component 62 is not limited to this; it may also be attached so as to abut against the rear end face of the tool holder body 10 and form a gap between it and the clamp nut 60.

[0048] Next, we will explain how to attach a cutting tool to such a collet-type tool holder 1.

[0049] Figure 2 shows the collet-type tool holder 1 before the cutting tool is attached, within area (b) of the cross-sectional view, and Figure 2 shows the collet-type tool holder 1 after a cutting tool (not shown) has been attached and fixed, within area (a) of the cross-sectional view.

[0050] First, when the clamp nut 60 is loosened, the sleeve 20 moves backward, and the pressing surface 23 of the sleeve 20 and the rear tapered surface 31 of the collet 30 are separated. At this time, no external load is applied to the collet 30, and the tool insertion hole 34 expands in diameter. Also, because the annular groove 33 of the collet 30 and the engaging rib 43 of the cap 40 are engaged, the collet 30 can reliably separate the pressing surface 23 of the sleeve 20 and the rear tapered surface 31 of the collet 30 without changing its position in the front-rear direction. With the tool insertion hole 34 expanded in this way, the cutting tool is inserted into the tool insertion hole 34 to a predetermined axial position.

[0051] Next, when the clamp nut 60 is tightened with a wrench or other tool, the sleeve 20 moves forward, and the pressing surface 23 of the sleeve 20 comes into contact with the rear tapered surface 31 of the collet 30. At this time, the guide surface 41 of the cap 40 slides against the outer circumferential surface 21 of the sleeve 20, and since the clearance between the two is set to be appropriately small, the axis of the pressing surface 23 of the sleeve 20 and the axis of the retaining surface 42 of the cap 40 are aligned on the same straight line.

[0052] When further force is applied to the work tool and the clamp nut 60 is tightened, a forward load is applied to the rear tapered surface 31 of the collet 30 via the pressing surface 23 of the sleeve 20. At this time, the front contact surface 32 of the collet 30 is in contact with the retaining surface 42 of the cap 40. Therefore, the front contact surface 32 receives a reaction force from the retaining surface 42. When an axial load is applied to the collet 30 in this way, the tool insertion hole 34 of the collet 30 is reduced in diameter, and the cutting tool is firmly gripped and fixed. Also, since the axis of the pressing surface 23 of the sleeve 20 and the axis of the retaining surface 42 of the cap 40 are located on the same straight line, the pressing surface 23 of the sleeve 20 is in proper contact with the rear tapered surface 31 of the collet 30, and the front contact surface 32 of the collet 30 is in proper contact with the retaining surface 42 of the cap 40. As a result, a uniform front-to-back load can be applied to the collet 30 in the circumferential direction.

[0053] Thus, with the collet-type tool holder 1 of this embodiment, the tightening operation required for changing cutting tools, which requires strong force, can be performed safely behind the tool holder body 10, rather than in front of the tool holder body 10 where the cutting edge of the cutting tool is located.

[0054] [Second Embodiment] The collet-type tool holder 1 according to the first embodiment described above has been described in the case where the tool holder body 10 is directly attached to the tool post 5. Next, a collet-type tool holder 1a according to the second embodiment, which has a structure different from the first embodiment, will be described. In addition, components that are the same as or similar to those in the first embodiment described above are denoted by the same reference numerals and their description is omitted.

[0055] Figure 5 shows a collet-type tool holder according to a second embodiment, where range (a) is a cross-sectional view showing the state in which the sleeve is positioned forward and the collet is reduced in diameter, and range (b) is a cross-sectional view showing the state in which the sleeve is positioned rearward and the collet is expanded in diameter. In this embodiment, "front-rear direction" is defined as the direction indicated by the arrow in Figure 5.

[0056] The second embodiment, as shown in Figure 5, has a structure in which the tool holder body 10a is integrated with the cap 40a and clamp nut 60, etc., and is removablely attached to the main body fixing part 70.

[0057] The main body fixing part 70 is a rectangular parallelepiped part and includes a cylindrical portion 71 into which the tool holder body 10a can be inserted at a position that matches the height of the spindle of the headstock 3. A guide portion 12 that fits into a groove formed in the tool post 5 is attached to the bottom surface of the main body fixing part 70. The guide portion 12 is a part with a substantially rectangular cross-section and is attached so as to extend in the width direction of the main body fixing part 70. The mounting position of the main body fixing part 70 in the front-rear direction relative to the tool post 5 is determined by the guide portion 12. Furthermore, it is preferable that a screw hole into which a set screw can be screwed is formed on the top surface of the main body fixing part 70 as a fixing means to prevent rotation and movement in the front-rear direction of the tool holder body 10a.

[0058] The tool holder body 10a is a substantially cylindrical component and has a cylindrical sliding part 11 inside into which a sleeve 20 can be inserted. A cap 40a is screwed onto the front end face of the tool holder body 10a. A clamp nut 60 is rotatably attached to the rear end face of the tool holder body 10a via a clamp nut retaining part 62a. Preferably, a flat surface is formed on a part of the outer circumferential surface of the tool holder body 10a, forming a flat surface that contacts a set screw attached to the top surface of the main body fixing part 70. Note that the fixing means for preventing rotational movement of the tool holder body 10a is not limited to the flat surface, but may be constructed using well-known techniques such as keys or pins. Furthermore, the tool holder body 10a may have a flat surface at a position radially opposite to the flat surface formed on its outer circumferential surface, forming two parallel flat surfaces. By providing two planes parallel to the tool holder body 10a in this way, when attaching the cap 40a with the tool holder body 10a removed from the main body fixing part 70, the tool holder body 10a can be gripped with a wrench or the like, and the cap 40a can be easily tightened onto the tool holder body 10a.

[0059] The cap 40a is a substantially cylindrical component, with a guide surface 41 formed on the inner surface of the rear end for sliding against the outer surface 21 of the sleeve 20, and a retaining surface 42 formed on the inner surface of the front end which tapers toward the front end. Between the guide surface 41 and the retaining surface 42, an engaging rib 43 is formed that engages with the annular groove 33 of the collet 30. At least one engaging rib 43 is formed, but multiple ribs may be formed. A threaded portion is formed on the outer surface of the rear end of the cap 40a so that it can be attached to the front end face of the tool holder body 10a. The outer diameter of the cap 40a is set to be smaller than the outer diameter of the tool holder body 10a.

[0060] The clamp nut retaining part 62a has a threaded portion that allows it to be attached to the rear end face of the tool holder body 10a. The clamp nut retaining part 62a rotatably supports the clamp nut 60 and prevents the clamp nut 60 from retracting from the tool holder body 10a. As shown in Figure 5, the clamp nut retaining part 62a may be attached so as to abut the clamp nut 60, or it may be attached so as to form a gap between it and the clamp nut 60. In addition, the outer diameter of the clamp nut retaining part 62a is set to be smaller than the outer diameter of the tool holder body 10a.

[0061] According to this second embodiment of the collet-type tool holder 1a, the cutting tool and collet 30 can be replaced while the tool holder body 10a, which is integrated with the cap 40a and clamp nut 60, is pulled out from the main body fixing part 70. Therefore, when changing cutting tools, the operator does not need to reach in front of the collet-type tool holder 1a where the cutting edge of the cutting tool is located, not only for the tightening work which requires strong force, but also throughout the entire process, making the cutting tool replacement work safer. In addition, since the tool holder body 10a is movable in the front-to-back direction relative to the main body fixing part 70, the front-to-back position of the cutting tool can be easily adjusted.

[0062] [Third Embodiment] The collet-type tool holder 1a according to the second embodiment described above has been described in a case where the tool holder body 10a is attached to the tool post 5 via a body fixing component 70, and the tool holder body 10a is removably attached to the body fixing component 70. Next, the collet-type tool holder 1b according to the third embodiment described below differs from the second embodiment in the shape of the tool holder body and the attachment structure of the tool holder body to the body fixing component 70. Note that components that are the same or similar as those in the first and second embodiments described above are denoted by the same reference numerals and their description is omitted.

[0063] Figure 6 shows a collet-type tool holder according to the third embodiment, where range (a) is a cross-sectional view showing the state in which the sleeve is positioned forward and the collet is reduced in diameter, and range (b) is a cross-sectional view showing the state in which the sleeve is positioned rearward and the collet is expanded in diameter. In this embodiment, "front-rear direction" is defined as the direction indicated by the arrow in Figure 6.

[0064] The tool holder body 10b is a substantially cylindrical component and includes a cylindrical sliding portion 11 into which the sleeve 20 can be inserted. The cylindrical sliding portion 11 is provided with an anti-rotation mechanism to prevent rotation of the sleeve 20 around its axis. For example, as shown in Figure 6, this mechanism consists of a pin 13b inserted into a pin hole in the tool holder body 10b and a keyway formed on a part of the outer circumferential surface 21 of the sleeve 20 corresponding to the diameter of the pin 13b. A cap 40a is screwed onto the front end face of the tool holder body 10b. A clamp nut 60 is rotatably attached to the rear end face of the tool holder body 10b via a retaining device. An expanding stepped stopper portion 14b is formed on the outer circumferential surface of the rear end of the tool holder body 10b. Preferably, a flat surface is formed on a part of the outer circumferential surface of the tool holder body 10b, which contacts a set screw attached to the main body fixing component 70. Furthermore, the fixing means for preventing rotational movement of the tool holder body 10b is not limited to a flat surface, but may also be constructed using well-known technologies such as keys or pins. In addition, the tool holder body 10b may have a flat surface on the radially opposite side of the flat surface formed on its outer circumferential surface, forming two parallel flat surfaces. By providing two parallel flat surfaces on the tool holder body 10b in this way, when attaching the cap 40a with the tool holder body 10b removed from the main body fixing part 70, the tool holder body 10a can be gripped with a wrench or the like, and the cap 40a can be easily tightened onto the tool holder body 10b.

[0065] According to the collet-type tool holder 1b of this third embodiment, when inserting the tool holder body 10b into the main body fixing component 70, the stopper portion 14b of the tool holder body 10b abuts against the rear end face of the main body fixing component 70, making it easy and reliable to determine the front-rear position of the tool holder body 10b relative to the main body fixing component 70. Therefore, according to the collet-type tool holder 1b of the third embodiment, the time required for changing the cutting tool and collet 30 can be reduced, and the cutting tool can be fixed with high precision.

[0066] In the above description, the method of attaching the tool holder body 10 and the main body fixing part 70 to the tool post 5 was explained in the case where it is done by the guide part 12 and the groove formed in the tool post 5. However, the attachment of the tool holder body 10 and the main body fixing part 70 to the tool post 5 is not limited to this, and for example, as shown in Figure 4(a), they may be attached to a tool post 5' which has an engaging part formed in a substantially V-shape in cross-section, so-called dovetail shape. In such a case, the tool holder body 10 and the main body fixing part 70 are fixed to the tool post 5' by clamping the engaging part of the tool post 5' from the front and rear directions. With this attachment method, as shown in Figure 4(b), bolts that pass through the tool holder body 10 and the main body fixing part 70 vertically become unnecessary, and it becomes possible to set the overall size of the collet-type tool holders 1, 1a, and 1b to be smaller in the width direction. It is clear from the description of the claims that such modified or improved forms may also be included in the technical scope of the present invention. [Explanation of Symbols]

[0067] 1 1a 1b Collet-type tool holder, 2 Lathe, 3 Headstock, 4 Spindle chuck, 5 Tool post, 10 10a 10b Tool holder body, 11 Cylindrical sliding part, 12 Guide part, 13 Key, 13b Pin, 14b Stopper part, 20 Sleeve, 21 Outer circumference, 22 Outer diameter thread part, 23 Pressing surface, 30 Collet, 31 Rear tapered surface, 32 Front contact surface, 33 Annular groove, 34 Tool insertion hole, 40 40a Cap, 41 Guide surface, 42 Retaining surface, 43 Engagement rib, 44 Locking part, 50 Cap holder, 51 Gap, 52 Stepped part, 53 Plunger, 60 Clamp nut, 61 Internal threaded section, 62 62a Clamp nut retaining part, 70 Main body fixing part, 71 Cylindrical section.

Claims

1. A collet-type tool holder for gripping a tool in a machine tool, A tool holder body having a cylindrical sliding portion extending in the axial direction of the tool, A collet having a rear tapered surface at its rear end in the axial direction and a front contact surface at its front end in the axial direction, A sleeve is slidably inserted into the cylindrical sliding portion and has a pressing surface that contacts the rear tapered surface of the collet, A cap is attached to the front of the tool holder body and has a pressing surface that contacts the front contact surface, and a guide surface into which the outer circumferential surface of the sleeve slidably fits, The tool holder body is provided with a sleeve sliding means for moving the sleeve back and forth in the axial direction from the rear of the tool holder body, The sleeve sliding means is characterized by comprising an external threaded portion formed on the sleeve and a clamp nut that screws into the external threaded portion, making it a collet-type tool holder.

2. In the collet-type tool holder according to claim 1, A collet-type tool holder characterized by comprising a cap locking mechanism for bringing the cap into close contact with the front end surface of the tool holder body.

3. In the collet-type tool holder according to claim 2, The collet-type tool holder is characterized in that the cap locking means comprises a locking portion formed on the periphery of the cap and a cap holder that presses against the locking portion.

4. In the collet-type tool holder according to claim 3, The cap holder is a collet-type tool holder characterized by having at least one plunger.

5. In the collet-type tool holder according to claim 1, The tool holder body is a collet-type tool holder characterized by being removablely attached to a main body fixing component.

6. In the collet-type tool holder according to claim 5, The collet-type tool holder is characterized in that the cap is fixed to the tool holder body by a threaded portion formed on the cap.

7. In the collet-type tool holder according to claim 6, The tool holder body has a stopper portion formed therein. The collet-type tool holder is characterized in that the stopper portion abuts against the rear end face of the main body fixing component.

8. In the collet-type tool holder according to claim 1, A collet-type tool holder characterized by comprising a rotation-preventing means for preventing rotation of the cylindrical sliding portion of the sleeve around its axis.

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