Screw-in tool and tool holder for such a screw-in tool

Abstract

A screw-in tool and a tool holder for such a screw-in tool. The screw-in tool contains a tool head and a tool shank having an outer thread and a supporting region arranged between the tool head and the outer thread. The supporting region is formed by two conical bearing faces having different cone angles.

Claims

1. A rotary tool for coupling with a rotatable threaded holder, the tool comprising: a tool head with a work surface and a conical first bearing surface formed in the tool head and defining a first cone angle; and a tool shank having a peripheral surface defining an outer periphery of the shank, the shank including an external thread integrally formed upon the peripheral surface and threadably engageable with the holder, the tool shank and the thread thereby formed as one piece, the tool shank further having a conical second bearing surface formed in the shank and defining a second cone angle, the second bearing surface positioned along the peripheral surface; the first and second cone angles define different angles; the first and second bearing surfaces are each shaped to directly contact and mate with a respective bearing surface of the holder; and the first and second bearing surfaces are adjacent to one another.

2. The tool according to claim 1, wherein the first bearing face forms an inner angle of 80° to 89° with respect to the axis of rotation, and the second bearing face forms an inner angle of 1.5° to 7° with respect to the axis of rotation.

3. The tool according to claim 1, wherein a third bearing face is provided on an inserted end of the tool shank and which has a spherical, cylindrical, or conical shape.

4. The tool according to claim 1, wherein the outer thread contains a thread depth that declines toward the free end of the tool shank.

5. The tool according to claim 1, wherein a gripper groove for the clamping of the rotary tool is provided on the tool shank.

6. The rotary tool of claim 1, further including a plurality of key surfaces formed in a circumference of the tool head, the key surfaces shaped to matingly engage an automated tool changer to thereby enable rotation of the tool head by the automated tool changer to securely engage the rotary tool within a tool holder.

7. The rotary tool of claim 1, wherein the thread is directly adjacent one of the two conical bearing faces.

8. A rotatable tool holder for a rotary tool, comprising: a holder opening with a tapered threaded inner surface threadably mateable with a tapered external surface of the rotary tool; a supporting region situated between a front side of the tool holder and the inner thread; the supporting region formed by two conical contact surfaces with different cone angles each shaped to directly contact and mate with corresponding surfaces of the rotary tool; cones which are defined by the two conical contact surfaces have apexes which point in the same direction; and the two conical contact surfaces are directly adjacent to one another.

9. The tool holder according to claim 8, wherein the supporting region is formed by a first conical contact surface adjacent to the front side of the tool holder, with an inner angle of 80° to 89° with the axis of rotation, and a second conical contact surface, at an inner angle of 1.5° to 7° with the axis of rotation.

10. The tool holder according to claim 8, wherein an inner bearing surface is provided at an inner end of the holder opening, and the inner bearing surface is designed as a cylindrical, spherical or conical contact surface.

11. The tool holder according to claim 8, wherein the inner thread contains a thread depth that declines toward the inner end of the holder opening.

12. The tool holder according to claim 8, wherein the tool holder contains a threaded insert for fixing the rotary tool.

13. A tool assembly, comprising: a rotary tool including: a tool head having a working surface and a conical head bearing surface formed in the tool head and defining a first cone angle; and a tool shank having a peripheral surface defining an outer periphery of the shank, the tool shank including an external thread integrally formed upon the peripheral surface, the tool shank and the thread thereby formed as one piece, the tool shank further having a conical shank bearing surface formed in the shank and defining a second cone angle, the shank bearing surface positioned along the peripheral surface; the first and second cone angles define different angles; cones defined by the first and second cone angles are coaxial and have apexes which point in the same direction; and the head and shank bearing surfaces are adjacent to one another; and a tool holder including: a holder opening; an inner thread formed upon a tapered inner surface of the holder and mateable with the thread of the tool shank; a front bearing surface situated upon a front side of the tool holder mateable with the head bearing surface; an inner bearing surface situated adjacent to the inner thread, the inner bearing surface mateable with the shank bearing surface; the front and inner bearing surfaces defining relatively different cone angles, the front and inner bearing surfaces shaped to directly and matingly engage with the head and shank bearing surfaces; and cones defined by the front and inner bearing surfaces point in the same direction and are adjacent to one another.

14. The tool assembly according to claim 13, further including an additional supporting region formed by an interference fit between a leading end of the rotary tool shank and the tool holder.

15. The tool assembly according to claim 13, wherein the outer thread of the rotary tool and the inner thread of the tool holder exhibit different thread contours which adjust to one another through elastic deformation when screwed together.

16. The tool assembly according to claim 13, wherein the outer thread of the rotary tool has a smaller pitch than the inner thread of the tool holder.

17. The tool assembly according to claim 13, wherein the outer thread is arranged on a threaded stem and the outer thread comprises a thread depth which decreases towards the free end of the threaded stem.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Special features and qualities of the invention can be deduced from the following description of preferred embodiment examples with the aid of the drawings. The figures show the following:

(2) FIG. 1, a tool holder and a screw-in tool in a longitudinal section;

(3) FIG. 2, the tool holder and the screw-in tool of FIG. 1 in a perspective view;

(4) FIG. 3, a detailed view X of FIG. 1;

(5) FIG. 4, a detailed view Y of FIG. 1;

(6) FIG. 5, a detailed view Z of FIG. 1;

(7) FIG. 6, a screw-in tool with a trapezoidal thread;

(8) FIG. 7, a screw-in holder for a screw-in tool according to FIG. 6;

(9) FIG. 8, a screw-in tool with a flat thread;

(10) FIG. 9, a tool holder for a screw-in tool according to FIG. 8;

(11) FIG. 10, another embodiment example of a screw-in tool with a trapezoidal thread;

(12) FIG. 11, an enlarged partial view Y of FIG. 10;

(13) FIG. 12, another embodiment example of a tool holder and a screw-in tool in a longitudinal section; and

(14) FIG. 13, an enlarged partial view Y of FIG. 12.

DETAILED DESCRIPTION OF THE INVENTION

(15) FIGS. 1 and 2 show a tool arrangement with a screw-in tool 1 and a corresponding tool holder 2 in a longitudinal section and a perspective view. The screw-in tool 1 has a tool head 3, which is designed here as a spherical-head cutter, and a tool shank 4, which tapers conically toward the rear, with an outer winding 5. A first supporting region with a first conical bearing face 6 is provided between the tool head 3 and the outer winding 5 for the placement on a counter-conical contact surface 7 on a front side of the tool holder 2, and a second conical bearing face 8 for the placement on a second conical contact surface 9 in the interior of the tool holder. In this way, a double cone, which ensures an improved centering and an increased supporting effect, is produced on the transition between the tool head 3 and the outer winding 5. A second supporting region 11 is found on a free rear end 10 of the tool shank 4.

(16) As can be seen particularly from FIG. 2, the tool head 3 has, on its outside, several key surfaces 12 distributed over the circumference for the screwing in of the screw-in tool 1 into the tool holder 2. The key surfaces 12 can also be used for the automatic tool change in the cutter. There is also a gripper groove 13 in the rear area of the tool shank 4 for the automatic clamping of the screw-in tool 1 in the tool holder 2 between the rear end of the outer thread 5 and the second rear supporting region 11. Pincer-like gripper elements of a clamping device, for example, can grip into the gripper groove 13, so as to be able to securely grip or hold the screw-in tool 1 in the tool holder 2. A central passage opening 14, which can be seen in FIG. 1, also runs through the screw-in tool 1, and it is possible to conduct the cooling lubricant, the compressed air, or another work fluid through this passage opening to the processing area. The passage opening 14 is situated coaxial to the middle axis 15 of the screw-in tool 1, but other arrangements, for example, with genuinely parallel or angular longitudinal axes are also possible, however.

(17) The tool holder 2 belonging to the screw-in tool 1 has a holder opening 16 with an inner thread 17. An outer supporting region with the first contact surface 7 for placement on the first bearing face 6 and with the second contact surface 9 for placement on the second bearing face 8 of the screw-in tool 1 is provided on the front side of the tool holder 2. A supply opening 19, coaxial to its middle axis 18, for the supply of a work fluid to the passage opening 14 of the screw-in tool 1 is also located in the tool holder 2, wherein here also, another arrangement comparable to the passage opening 14 is possible. Radial boreholes 20 can also be located in the tool holder 2; they open into the holder opening 16 or also into the supply 19. A sleeve 22, provided with an annular groove 21 on the inside for the outer cooling agent supply can be situated on the outside of the tool holder 2. The annular groove 21 can likewise, however, also be formed on the tool holder 2.

(18) In the embodiment shown in FIGS. 1-7, the outer thread 5 of the screw-in tool 1 and the corresponding inner thread 17 of the tool holder 2 are constructed as a trapezoidal thread with a flank angle of 30°, shown in FIG. 3. The outer thread 5 of the screw-in tool 1 and the corresponding inner thread 17 of the tool holder 2 can, however, also be constructed as a trapezoidal thread with other flank angles. In contrast to the traditional threads, in which the thread turns have a constant thread depth, the outer thread 5 used here has a thread depth which declines from the tool head 3 toward the free rear end 10 of the tool shank 4. Also, with the inner thread 17 of the tool holder 2, the thread depth declines from the second contact surface 9 toward the second supporting region 11.

(19) From FIG. 4, it can be seen that the first bearing face 6 of the screw-in tool 1 and the corresponding first contact surface 7 of the tool holder 2 are inclined by 5° relative to a plane that is vertical with respect to the middle axes 15 and 18, in the direction of the front end of the tool head 3. In this way, the first conical bearing face 6 and also the first conical contact surface 7 have a cone angle of at least 140° and a maximum 179°, but preferably 170°. The diameter of the second conical bearing face 8 of the screw-in tool 1 and the diameter of the second conical contact surface 9 of the tool holder 2 taper in the screw-in direction, so that the result is a cone angle of at least 1° and a maximum of 90°, but preferably 10°, which means an angle of the cone surfaces of 5° relative to the middle axes 15 and 18.

(20) The second supporting region 11 of the screw-in tool 1 is designed with a spherical shape in accordance with FIG. 5 and is placed on a cylindrical bearing face 24 at the end of the holder opening 16. The cylindrical bearing face 24 forms another inner bearing area in the tool holder. The spherical supporting region 11 ensures an only parallel contact between the screw-in tool 1 and the tool holder 2. Appropriately, the second spherical supporting region 11 has an excess in comparison to the cylindrical bearing face 24, so that the pretension in this second supporting region is independent of the screwing depth.

(21) Another embodiment example of a screw-in tool 1 and a corresponding tool holder 2 is shown in FIGS. 8 and 9. In contrast to the embodiment of FIGS. 6 and 7, the outer thread 5 of the screw-in tool 1 and the inner thread 17 of the tool holder 2 are constructed as flat threads in this embodiment example. Otherwise, this embodiment corresponds to the previous embodiment example, so components that correspond to one another are also provided with the same reference symbols. In this embodiment also, the outer thread 5 used here has a thread depth that declines from the tool head 3 toward the free end 10 of the tool shank 4. Furthermore, here too, the thread depth declines from the second contact surface 9 toward the second supporting region 11 in the inner thread 17 of the tool holder 2.

(22) FIGS. 10 and 11 show an embodiment example in which the diameters of the conical first bearing face 6 of the screw-in tool 1 and the corresponding conical first contact surface 7 of the tool holder 2 expand in the screwing direction of the screw-in tool 1. The first bearing face 6 and the corresponding first contact surface 7 are inclined around 5°, relative to the plane, vertical to the middle axes 15 and 18, in the direction of the tool shank 4. In this way, the first conical bearing face 6 and also the first conical contact surface 7 have a cone angle of 170°, just as in the embodiment example from FIG. 4. The second conical bearing face 8 and the second conical contact surface 9 taper at an angle of 5° relative to the middle axes 15 and 18, so that a cone angle of 10° is produced. In contrast to the embodiments of FIGS. 1-9, the cones that underlie the two conical surfaces forming the double cone point in opposite directions.

(23) FIG. 12 shows an embodiment example in which a threaded insert 25, which contains the second conical contact surface 9, the inner thread 17, and the cylindrical bearing face 24, is inserted into the holder opening 16 of the tool holder 2. The radial boreholes 20 go through the tool holder 2 and the threaded insert 25 and lead into the holder opening 16 of the tool holder 2.

(24) FIG. 13 shows an enlarged representation of the sleeve 22 for the outer cooling agent supply. In the direction of the tool, the sleeve 22 has one or more outlets 26, through which the cooling agent guided outward via the radial boreholes 20 and exiting through the outer openings 23 can be conducted to the tool or to the site to be processed. The exit(s) 26 can be designed as a surrounding slot, boreholes, slits, or the like.

(25) In the tool arrangement according to a first advantageous form of embodiment, the thread and the corresponding mating thread can exhibit different thread contours which adjust to one another through elastic deformation when screwed together. This has the advantage that when they are screwed together, a preload is generated through one part of the thread by elastic deformation of the threads and when secured a uniform pattern of contact is obtained over the entire length of the thread. This allows the tensile strength of the entire thread to be utilized. The thread contour is to be understood to mean not the contour of a thread flank but the contour of the entire thread in the longitudinal section.

(26) In a second advantageous form of embodiment the thread and the mating thread exhibit a different pitch. The threaded connection can then be chosen so that the thread component embodied as the external thread exhibits a smaller pitch than the corresponding internal thread. This allows the thread flanks to be elastically stretched or compressed by the screwing process in such a way that the thread contours adapt to one another. As a result the thread turns are in contact with one another in their entirety and a uniform pattern of contact can be obtained.

(27) In a third advantageous form of embodiment the thread and the mating thread can be embodied as a tapering internal thread and external thread with different taper angles. This also allows stretching and compression of certain thread regions and hence a uniform pattern of contact for the threaded connection. In one particularly preferred form of embodiment the taper angle of the internal thread is greater than the taper angle of the external thread. The result of this specific design is that the thread turn of the external thread has a greater diameter than the corresponding turn of the internal thread. Thus, through the preferably inclined thread flanks this part of the external thread comes into contact with the internal thread first and therefore also comes under load first. When the threads are secured, this region deforms elastically and the thread contours adapt to one another. In this way a uniform pattern of contact can be obtained.

(28) The invention is not limited to the embodiment examples described in the preceding and shown in the drawing. Thus, for example, the outer cooling agent supply with the radial boreholes and the sleeve, the gripper groove for the automatic tension in a tool machine, the threaded insert, or also the embodiment of the tool holder made of fibrous composites with screw-in tools or tool holders can be used individually or in combination, in which only simple conical, cylindrical, or plane bearing or contact surfaces or other centering or guiding possibilities are used. These embodiments are not limited to screw-in tools or holders with a double cone.