WO2005097382A1

WO2005097382A1 - Tool spindle

Info

Publication number: WO2005097382A1
Application number: PCT/IT2004/000178
Authority: WO
Inventors: Cornelio Molteni
Original assignee: Cornelio Molteni
Priority date: 2004-04-06
Filing date: 2004-04-06
Publication date: 2005-10-20

Abstract

The present invention relates to a quick blocking and unblocking tool spindle (1), comprising a body (3) having a machine tool end (7) and a tool end (5), the body (3) being provided with an axial hole (9), which is opened at the tool end (5)and which is able to receive the tang (31) of a tool, and tool blocking means placed in said axial hole (9) comprising a plurality of rollers (11), whose axis of rotation is coaxial with the axis (Z) of the spindle (1), for which the rotation around their axis in one direction is allowed and the rotation around their axis in the opposite direction is prevented, having the function of blocking in a stable way the tang (31) of the tool. The tool spindle (1) further comprises means for centering and supporting the tang (31) of the tool in said axial hole (9).

Description

"TOOL SPINDLE"

The present invention is about a quick blocking and unblocking tool spindle. It is known that a spindle comprises a metallic body of substantially cylindrical shape, having one end suitable for being connected to a machine tool and the opposite end provided with an axial hole for the insertion of a tool. Means for blocking in position the tool are provided inside the axial hole. The blocking means usually comprise a collet, or a similar device, able to be partially expanded and clasped in order to block firmly the extremity, or tang, of a tool inserted in the axial hole of the spindle. To use such kind of spindle, the operator inserts the tang of the tool in the axial hole, and subsequently clasps the collet from the outside, with the aid of a proper implement, to block the tang inside the hole. When the working which requires this particular kind of tool is finished, the operator unblocks the collet using the same implement to remove said tool. It is evident from the preceding description that, if different kinds of working using different tools must be performed, the operator should repeat several times the aforesaid collet blocking and unblocking operations for changing the tool, with considerable increase of working times, especially when complex workings are required. It is thus an object of the present invention to provide for a quick blocking and unblocking tool spindle which overcomes the disadvantages of the prior art, allowing to assemble and disassemble the tool without requesting any effort from the operator. It is a further object of the invention to provide for a quick blocking and unblocking tool spindle which allows a better precision in the insertion of the tool and a greater clamping strength for said tool. These and other objects, which will be better highlighted in the following detailed description, are reached by tool a spindle according to the contents of the main claim. In a preferred embodiment of the tool spindle according to the present invention, cylindrical contact bodies able to rotate in a single direction are provided on the internal wall of the axial hole, having the function of blocking in a stable and precise way the tang of the tool inside the spindle. In this or another preferred embodiment of the invention, at least a bearing or a centering ring is provided, so that the axis of the tool is coaxial with the axis of the spindle. Also in this or another preferred embodiment of the invention, support means for the tool are provided in the axial hole, comprising a collet or a magnet. In this or another preferred embodiment of the invention, a bush keyed inside the spindle is furthermore provided, whose function is to hold a spring inside which the tang of the tool is inserted. These and other characteristics, and advantages of the present invention will be better highlighted in the following description of a preferred embodiment of the same invention, given just as an example, with reference to the annexed drawings wherein: Figure 1 is a longitudinal sectional view of the spindle according to the invention; Figure 2 is a cross sectional view showing the working of the cylindrical contact bodies in a first operative configuration; and Figure 3 is a cross sectional view showing the working of the cylindrical contact bodies in a second operative configuration. With reference to Figure 1 the spindle, generally indicated with numeral 1 , comprises a steel body 3 of elongated shape, having a tool end 5 and a machine tool end 7, also known as shank. The shank 7 has a preferably conical shape, but it can also have a cylindrical shape. The shank 7 is connected to a machine tool (not shown), for example a milling machine, which gives a clockwise or anticlockwise rotating movement to the spindle 1 around its axis Z. The body 3 is provided with an axial hole 9 which is opened at the tool end 5. The axial hole 9 is of cylindrical shape, with its axis of symmetry coincident with the axis 2. On the bottom of the axial hole 9 a support of antimagnetic material, preferably brass, can be fixed. In this support, a seat in which a magnet (not shown) can be keyed is provided. Advantageously, the magnet will be of permanent type. More advantageously, the permanent magnet can be made of rare earth elements. According to a preferred embodiment of the invention, cylindrical contact bodies or rollers 11 are provided on the internal wall of the axial hole 9, whose axis of rotation is coaxial with the axis Z of the spindle 1 , for which the rotation around their axis in one direction is allowed and the rotation around their axis in the opposite direction is prevented, having the function of blocking in a stable way the tang 31 of a tool. With combined reference to the Figures 2 and 3, a possible operation mode of the rollers 11 according to a preferred embodiment is disclosed. Each roller 11 is inserted in a proper seat 37 and it is maintained in position by a spring 35. When the roller 11 is forced to move in the movement direction Di of the tool tang 31 in contact therewith (see Figure 2), said roller 11 is able to rotate freely inside its seat 37. If the roller 11 is forced to rotate in the opposite direction D₂, as shown in Figure 3, it is wedged between the seat 37 and the surface of the tool tang 31 , being instantaneously blocked. The rollers 11 can be directly fixed inside the axial hole 9 of the tool end 5 of the spindle 1, or they can be provided inside one or more freewheels 13 and 15, coaxially fitted in sequence in the wall of the axial hole 9, said freewheels 13 and 15 defining therein a passage for the tool tang 31. The number of the freewheels can change according to the needs. So, for example, instead of one of the freewheels, in particular instead of the freewheel 13 nearer to the mouth of the axial hole 9, a bearing or a centering ring (not shown) can be provided, so that the axis of the tool is coaxial with the axis of the spindle 1. With reference to the above description and the Figure 1 , the working of the tool spindle according to the present invention will be explained. The spindle 1 is connected at first to the machine tool (not shown). The tang 31 of a tool is then inserted in the axial hole 9. The internal end of the tang 31 has a plane surface 33 so that, when the tool is inserted in the axial hole 9, said plane surface 33 abuts against a spacer element 17. In this way, the spacer element 17, comprising a spring 19, will hold the tang 31 of the tool inside the axial hole 9, avoiding its fall outside when the spindle 1 is for instance in a vertical position, as shown in Figure ;1. For holding the tang 31 of the tool inside the axial hole 9 it is also possible to use a double bush 23, in which one bush slides inside the other by a plurality of spheres 25, also sliding in a single direction inside a conical cavity 27, which block the tang 31 of the tool avoiding its vertical fall. To remove the tool from the axial hole 9 of the spindle 1 it is sufficient to use a proper implement, suitable for being inserted in the holes 29 obtained at each sphere 25, for unblocking said spheres 25 and releasing the tool. The spring 19 system and the bush 23 system can be used either in a separate way or in mutual combination, according to the operative requirements of the spindle 1. Obviously, instead of the aforesaid supports, any other support means for the tool can be used, for example a collet. One or more centering rings 21 are furthermore provided for obtaining that the axis of the tool is coincident with the axis Z of the spindle 1, to avoid dangerous vibrations during the rotation of said spindle 1. It is important to note that the rings 22 and 23, disposed at the extremities of the axial hole 9 to obtain a greater precision, can also be positioned in a different way. At this point, the machine tool is operated to rotate the spindle 1 around its axis Z and said spindle 1 is brought near and put in contact with a workpiece (not shown). The contact between the rotating tool and the workpiece causes a frictional torque, opposed to the motive power which generates the rotation of the tool. This torque will try to rotate the tool inside the axial hole 9. However, the rollers 11 provided inside the axial hole 9 or in the freewheels 13 and 15 will oppose this rotation, being configured to be blocked in the previously described manner when they are put in rotation in the opposite direction to the expected one, that is the direction D₂ shown in Figure 3. In this way, the tang 31 of the tool will be firmly blocked inside the axial hole 9, so that the tool will be rotated by the machine tool only, to perform the operation. Once the operation is performed, the spindle 1 together with the tool will be moved away from the workpiece. The tool could be removed from the axial hole 9 by simply rotating it with a hand or with proper implements, according to the particular embodiment of the spindle 1 , in the rotation direction of the rollers 11. Thus, the tool spindle according to the present invention fully achieves the intended purposes and objects. In fact, a spindle 1 which allows to assemble and to block any kind of tool quickly and without needing other implements is provided. The tool spindle according to the invention is furthermore made of few simple elements, easily available on the market at a low cost. In this connection, it is important to note that the magnet or any other support means may even be dispensed with. In fact, it is sufficient that the operator holds the tool with a hand, so that it does not fall outside the axial hole 9 of the spindle 1 until its drill bit is put in contact with the surface of the workpiece. It is evident that alterations, additions and variations could be resorted to the embodiment previously described in an illustrative way, without falling outside the scope of protection of the invention, as it is also defined in the appended claims.

Claims

1. A quick blocking and unblocking tool spindle (1 ) comprising: • a body (3) having a machine tool end (7) and a tool end (5), said body (3) being provided with an axial hole (9), which is opened at said tool end (5), able to receive the tang (31 ) of a tool, • tool blocking means placed in said axial hole (9), wherein said blocking means comprise a plurality of rollers (11), whose axis of rotation is coaxial with the axis (Z) of said spindle (1), for which the rotation around their axis in one direction is allowed and the rotation around their axis in the opposite direction is prevented, having the function of blocking in a stable way said tang (31 ) of a tool.

2. The tool spindle (1) according to claim 1, wherein said rollers (11) are provided on the internal wall of said axial hole (9).

3. The tool spindle (1) according to claim 1 , wherein said rollers (11) are provided inside at least a freewheel (13) disposed in said axial hole (9), said freewheel (13) defining therein a passage for said tang (31) of a tool.

4. The tool spindle (1) according to claim 1 , wherein said axial hole (9) is provided with at least a centering means for said tang (31) of a tool.

5. The tool spindle (1) according to claim 4, wherein said at least a centering means comprises one or more centering rings (21) so that the axis of the tool is coaxial with the axis (Z) of the spindle (1).

6. The tool spindle (1) according to claim 1 , wherein said axial hole (9) is provided with at least a support means for said tang (31 ) of a tool.

7. The tool spindle (1) according to claim 6, wherein said at least a support means is provided with a spacer element (17), comprising at least a spring (19) able to hold said tang (31) of a tool in said axial hole (9).

8. The tool spindle (1) according to claim 6, wherein said at least a support means comprises at least a double bush (23), in which one bush slides inside the other by a plurality of spheres (25), each of said spheres (25) sliding in a single direction inside a conical cavity (27) to block in position said tang (31) of a tool in said axial hole (9).

9. The tool spindle (1) according to claim 6, wherein said at least a support means comprises a collet.

10. The tool spindle (1) according to claim 6, wherein said at least a support means comprises a magnet.