WO2004091854A1

WO2004091854A1 - Device for fixing a rotational tool to a tool holder

Info

Publication number: WO2004091854A1
Application number: PCT/EP2004/004071
Authority: WO
Inventors: Franz Haimer
Original assignee: Franz Haimer Maschinenbau Kg
Priority date: 2003-04-16
Filing date: 2004-04-16
Publication date: 2004-10-28
Also published as: DE10317576B4; DE10317576A1

Abstract

A stop mandrel (25) is provided in order to preset the total length (L) of a tool unit (1), comprising a rotational tool (3) and a tool holder (5), in order to pre-fix a rotational tool (3), for example, a drill or a milling cutter, to a tool holder (5) which holds the shaft (7) of the rotational tool (3) in a press fit in a receiving opening (11) of a bushing section (13) and which releases it during heating of the bushing section (13) by means of an induction coil (17). The scaling means (35) are associated with the stop mandrel and enable the stop mandrel, when the rotational tool (3) has a known length, to be placed in a position wherein it defines the depth of insertion of the rotational tool (3) for later fixing in order to obtain the desired total length (L).

Description

Device for clamping a rotary tool in a tool holder

description

The invention relates to a device for clamping a rotary tool, in particular a drilling or milling tool in a tool holder, which holds a shaft of the rotary tool in a press fit in a receptacle opening of a sleeve section that is central to the axis of rotation and releases it when the sleeve section is heated.

From WO 01/89 758 A1 it is known to use rotary tools such as e.g. Drill or milling cutter to be held in a central receiving opening of a tool holder only in the press fit of a sleeve section of the tool holder forming the receiving opening. The sleeve section of the tool holder can be heated to such an extent by means of an inductive heating device, for example in the form of an induction coil that surrounds the sleeve section, that the shaft of the rotary tool can be inserted into or removed from the receiving opening that widens as a result. The outer diameter of the shaft is slightly larger than the nominal inner diameter of the receiving opening, so that when the sleeve section has cooled, it holds the shaft in a press fit.

Conventional tool holders of the above type have a standard coupling, for example a steep taper coupling or an HSK coupling, by means of which the tool holder is coupled to the spindle of the working machine coaxially with its axis of rotation. A reference stop surface or a reference position of the tool holder in this case allows the axial position of the rotary tool to be measured in a reproducible manner relative to the spindle or to the tool holder by means of a conventional, the distance between the reference stop surface or reference position of the tool holder and the tip of the rotary tool measuring length measuring device and thus a reproducible axial positioning of the rotary tool relative to the spindle.

It is also known to arrange an axially adjustable positioning stop surface, for example in the form of an axially projecting screw screwed into the tool holder in the receiving opening of a "shrink tool holder" of the type explained above, which adjustably limits the immersion depth of the tool shaft when shrinking.

The length of the tool unit formed from the rotary tool and the tool holder can be adjusted to the desired length value when the sleeve section is heated and thus the axially movable rotary tool. However, this procedure can lead to setting errors, since the axial thermal expansion of the tool holder must be taken into account to compensate. Adjustment errors of this type are avoided if the positioning stop surface is adjusted with the tool holder cold so that the tool unit has the desired length after the rotary tool has been shrunk in. However, it has been shown that measuring methods which allow the desired length of the tool unit to be preset when the tool holder is still cold are comparatively complex to handle and involve a comparatively high outlay on measuring apparatus.

It is an object of the invention to provide a device which is easy to use and which allows simple means to shrink a rotary tool into a desired position relative to a tool holder without this causing adjustment errors due to axial thermal expansion of the tool holder. In achieving this object, the invention is based on a device for clamping a rotary tool in a tool holder, which holds a shaft of the rotary tool in a press fit in a receiving opening of a sleeve section which is central to the axis of rotation and releases it when the sleeve section is heated, the tool holder releasing one which is coaxial with the axis of rotation Coupling section having an axial through channel extending into the receiving opening. The device in this case comprises a holder receptacle centered with the coupling section of the tool holder relative to the axis of rotation and to be coupled in a predetermined axial position, a heating device for heating the sleeve section of the tool holder coupled with the holder receptacle, a tool positioning device with a device which can be moved in the direction of the rotation axis to a selectable position relative to the

Tool holder surface adjustable for a front end of the rotary tool and is characterized in that the tool positioning device has a central stop pin, which extends into the through opening of the tool holder coupled to the holder holder and is movable in the direction of the axis of rotation, at its end located in the tool holder forms the tool stop surface for the front end of the shaft of the rotary tool and that the stop mandrel is assigned scale means by means of which the tool stop surface of the stop mandrel can be set to a predetermined axial distance from an axial reference position of the tool holder coupled to the holder receptacle.

The invention is based on the consideration that the reference position of the tool holder coupled to the holder holder is different from that for the

Shrinking process to be heated sleeve section is sufficiently thermally insulated and thus in its axial position relative to the holder receptacle not changed. Since the stop mandrel is fixed relative to the holder holder, the tool stop surface can be positioned independently of the thermal expansion of the sleeve section, so that thermal expansion errors are avoided. Since the axial length of the rotary tool is generally known or can be measured without any problems, a desired total length of the tool unit consisting of the tool holder and the rotary tool shrunk therein can be preset with sufficient accuracy if the stop mandrel is adjusted so that its tool stop surface is around the Difference of the two lengths above the reference position of the tool holder protrudes. Since the scale means are directly assigned to the stop mandrel, the position of the stop dome required for the desired total length of the tool unit can be set directly using these scale means before the heating of the sleeve section and the shrinking process is started. This simplifies handling, in particular since the length of the rotary tool can be determined in a separate measuring step and the rotary tool is not physically required when positioning the dome.

In a preferred embodiment it is provided that the stop mandrel is displaceably guided on a guide relative to the holder receptacle and the scale means comprise a scale scale for measuring the displacement distance of the stop dome. The position of the stop dome relative to the holder receptacle and thus also relative to the reference position of the tool holder coupled to the holder receptacle can be easily measured and / or adjusted in this way. The scale scale can be part of a mechanical position measuring arrangement, such as a conventional micrometer screw, on the scale of which both the position and the displacement distance of the stop dome connected to the micrometer screw can be read and adjusted exactly. In a variant it can be provided that the scale Scale is part of an electrical displacement measuring arrangement, so that the position and / or the displacement distance can be shown on a display of the displacement measuring arrangement.

The stop mandrel can be moved by hand if necessary via a gear. Particularly when using an electrical displacement measuring arrangement, however, the tool positioning device preferably comprises an electrical positioning drive for the stop mandrel which responds to the displacement measuring arrangement.

The embodiments explained above use an optically, electrically or magnetically readable scale scale for determining the position of the dome. Such a scale can be dispensed with if the tool positioning device uses a stepper motor positioning drive for the displacement movement of the stop dome, in which case the scale means for measuring the displacement distance of the stop dome have a counter which counts the steps of the stepper motor positioning drive. This makes use of the fact that electrical stepper motors which can be switched by pulses rotate in a sequence of rotary steps of constant angular width, so that the number of pulses which switch the stepper motor is at the same time a measure of the rotary path covered by the stepper motor.

In order to facilitate the position adjustment of the stop dome, it is expediently provided that the scale means set to the axial reference position of the tool holder coupled to the holder receptacle can be set to the scale value "zero". A “calibration master”, that is to say a component corresponding to the coupling section of the tool holder, is expediently used for this “zeroing”, which component forms an axial stop surface for the stop mandrel in the reference position. The position to which the tool stop surface of the stop dome is to be adjusted relative to the reference position of the tool holder can be formed from the desired total length of the tool unit consisting of the rotary tool and the tool holder minus the axial length of the rotary tool by simple subtraction. The handling of the device according to the invention can be considerably simplified if the tool positioning device comprises a positioning drive driving the stop mandrel for its adjustment movement and the positioning drive is assigned a data input device on which values for the axial length of the rotary tool and the desired total length of the tool unit can be entered. The difference between the desired total length minus the length of the rotary tool is then advantageously carried out automatically.

The tool positioning device explained above is preferably combined together with an inductive heating device to form a structural unit. A modular design is achieved if this structural unit can be expanded by a cooling station designed as a further structural unit for the tool holder heated by means of the heating device. The holder receptacle is expediently movably guided between the two structural units, so that the tool holder to be cooled, together with its holder receptacle, can be moved, for example, on a linear guide between the module comprising the heating device and the cooling station module. In practice, several of the holder receptacles of the same or different sizes can be arranged on a turntable in order to accelerate the workflow during continuous operation. In a preferred embodiment, the turntable that unites a plurality of holder receptacles can then be displaced between the modules by means of the linear guide.

Exemplary embodiments of the invention are explained below with reference to a drawing. Here shows: Figure 1 is a partially sectioned, schematic representation of a device for clamping a rotary tool in a tool holder with presetting the length of the tool unit thus formed.

Fig. 2 is a partially broken perspective view of an embodiment of the device and

3 shows a perspective representation of a variant of the device from FIG. 2.

The tool clamping device shown schematically in FIG. 1 allows the length of a tool unit 1 to be preset, which consists of a rotary tool 3, for example a drill or milling cutter and a tool holder 5. The rotary tool 3 sits with its shaft 7 in a press fit in a receptacle opening 11 of a sleeve section 13 of the tool holder 5, which is centered on the axis of rotation 9 A coupling section 15 facing away from the sleeve section 13, for example in the form of a standardized steep taper or a standardized HSK coupling.

In order to clamp the rotary tool 3 in the sleeve section 13 or to unclamp it from the sleeve section 13, the sleeve section is heated and thereby stretched to an inner diameter which releases the shaft 7 of the rotary tool 3. An induction heating device is provided for heating, as described for example in WO 01/89 758 A1. The induction heating device comprises an induction coil 17, in particular fed with high-frequency alternating current, which induces eddy currents in the metallic sleeve section 13, by means of which the sleeve section 13 is heated to temperatures of several 100 ° C. and thus stretched. For later use in the working machine, the tool unit 1 should have a predetermined total length L in the direction of the axis of rotation between a free end 19 of the rotary tool 3 remote from a tool holder and a defined reference position 21, for example a predetermined diameter of the conical coupling section 15 or a predetermined contact surface of the coupling section 15, in order to be able to reproducibly specify the distance between the free end 19 of the rotary tool 13 and the spindle of the working machine, knowing this predetermined length L. The total length L is determined in the knowledge of the length L1 of the rotary tool 3 measured between the end face 19 and the end face 23 of the shaft, by means of a stop mandrel 25 which projects through a through-channel 27 penetrating the coupling section 15 into the receiving opening 11 of the sleeve section 13 and there with a stop surface 29 formed at its end and assigned to the front end 23 limits the insertion depth of the rotary tool 3 during the clamping process.

During the clamping process, the tool holder 5 is coupled via its coupling section 15 to a holder receptacle 31, which defines the reference position 21 of the tool holder 5 in the axial direction and fixes it in a reproducible manner. The stop mandrel 25, which can be displaced centrally on a guide 33 in the direction of the axis of rotation 9, can be positioned with the aid of a scale 35 measuring the displacement path of the stop dome 25 or defining its position, knowing the length L1, such that when the rotary tool 3 shrinks, the total length L results. For this purpose, the stop mandrel 25 is shifted from a starting value of the scale 35 representing the reference position 21 by a distance L2 which corresponds to the difference L - L1. The stop surface 29 is then in a position in which when shrinking it limits the insertion depth of the rotary tool 3 in accordance with the total length L of the tool unit 1. A "calibration master" can be used to determine the scale value of the reference position 21, which is a calibration gauge with a coupling section corresponding to the coupling section 15 and a stop surface for the stop mandrel 25 in the axial position of the reference position 21. Knowing the scale value assigned to the reference position 21 and the position value L2 related to the reference position 21, the scale mandrel 35 can be used to move the stop mandrel into the position leading to the desired overall length L and lock it there. It goes without saying that the scale scale 35 can be set to "zero" in individual cases with the help of the calibration master, so that the scale enables the length L2 to be set directly.

The induction coil 17 is guided so as to be displaceable in the direction of the axis of rotation 9 on a guide 37. 1 shows the induction coil 17 in a position in which the tool holder 5 can be inserted into or removed from the holder receptacle 31. For clamping the rotary tool 3, the induction coil 17 is lowered into a position in which it concentrically surrounds the region of the receiving opening 11 of the sleeve section 5. The receiving opening 11 is accessible from above, so that the rotary tool 3 can be inserted from above up to the stop on the stop surface 29 of the stop dome 25 preset as explained above when the sleeve section 5 is heated. The rotary tool can also be inserted by gravity.

The scale scale 35 can be an optical scale, as is known, for example, from mechanical micrometer measuring devices. However, electrical displacement measuring devices with optically or magnetically coded scales are also suitable, which scan the scale preferably without contact using a sensor 39 and show the displacement on a display 41. Displacement measuring devices of this type are known and are not to be explained in more detail. However, they are preferred in the present case because they can easily zero the dome 25 to the reference position 21 and can also include computing means which, when the lengths L and L1 are entered by means of an input device 43, for example a keyboard, can directly calculate and display the value L2 to be set. In a preferred embodiment, the displacement measuring device can be supplemented by means of an additional drive motor 45 to form a positioning drive for the displacement movement of the stop dome 25, with the aid of which, after the values L and L1 have been entered, the stop mandrel 25 automatically moves into the position L2 leading to the desired overall length L.

The scale scale 35 can be omitted if the positioning drive 45 can in turn be moved through defined distances, as is the case, for example, with an electric stepper motor which, due to its design, is advanced by a defined angle of rotation for each driver pulse supplied to it. With such a positioning drive, the distance traveled can be determined by counting the driver pulses. The counter (not shown in detail) can be set to zero for the reference position 21, so that the counter content directly represents the value L2.

FIG. 2 shows details of the presetting and shrinking device schematically explained with reference to FIG. 1, here with an adapter-like, interchangeable holder receptacle 31 for a tool holder 5 with a coupling section 15 in the form of an HSK standard coupling. The positioning drive (not shown in more detail) for the stop mandrel 25 is combined with the high-frequency generator feeding the induction coil 17 to form a module 47 forming a structural unit. The connecting cable of the induction coil 17, which can be displaced along the guide 37, can be seen at 49. The module 47 also carries the display 41 and the operating elements 43. A length measuring module 51 is connected to the module 47, with the aid of which the length L1 of a rotary tool 3 ′ to be clamped in can be measured before clamping. For this purpose, the length measuring module 51 has a measuring element 55, which is displaceably guided on a guide 53. Although the measured length value L1 can be shown on the display 41, it is preferably provided that the length information is used directly to control the positioning drive.

FIG. 3 shows the modular device explained with reference to FIG. 2 supplemented by a cooling module 57. The cooling module comprises a plurality of cooling sleeves 59, each connected to a coolant circuit, of different diameters adapted to the various tool holders. As explained in detail in WO 01/89 758 A1, the cooling sleeves can be placed on the sleeve section of the tool holder after the rotary tool has been clamped or unclamped in order to cool the tool holder rapidly to room temperature.

As also described in WO 01/89 758 A1, several of the holder receptacles 31 are arranged on a turntable 61 around its axis of rotation 63. In this way, different holder receptacles 31 but also several identical holder receptacles can be provided to accelerate the workflow. The turntable 61 is arranged on a slide 67 which can be displaced linearly on longitudinal guides 65 and can thus be pushed back and forth between the clamping module 47 and the cooling module 57. The clamping module 47 has a single stop mandrel 25 aligned coaxially with the induction coil 17, over which the holder receptacles 31 of the turntable 61 can be positioned in order.

Claims

Expectations

1 . Device for clamping a rotary tool (3), in particular a drilling or milling tool in a tool holder (5), which press-fits a shaft (7) of the rotary tool (3) in a receiving opening (1 1) of a sleeve section that is central to the axis of rotation (9) (1 3) holds and releases when the sleeve section (1 3) heats up, the tool holder (5) having a coupling section (1 5) which is coaxial with the axis of rotation (9) and has an axial through channel (27) extending into the receiving opening (1 1) ) comprising a holder receptacle (31) to be coupled with the coupling section (15) of the tool holder (5) to the axis of rotation (9) centrally and in a predetermined axial position, - a heating device (17) for heating the sleeve section

(13) of the tool holder (5) coupled to the holder holder (31), a tool positioning device with a tool stop surface (29) which can be moved in the direction of the axis of rotation (9) and can be adjusted to a selectable position relative to the holder holder (31) An end face (23) of the rotary tool (3), characterized in that the tool positioning device has a central stop mandrel (25) which extends into the through opening (27) of the tool holder coupled to the holder receptacle (31) and is movable in the direction of the axis of rotation (9) ) which forms the tool stop surface (29) for the front end (23) of the shaft (7) of the rotary tool (3) at its end located in the tool holder (5) and that scale means (35) are assigned to the stop mandrel (25) by means of which the tool stop surface (29) of the stop dome (25) is at a predetermined axial distance (L2) from an axial reference position (21) of the with the Holder holder (31) coupled tool holder (5) is adjustable.

2. Device according to claim 1, characterized in that the stop mandrel (25) on a guide (33) is displaceably guided relative to the holder receptacle (31) and the scale means comprise a scale (35) for measuring the displacement distance of the stop dome (25) ,

3. Device according to claim 2, characterized in that the scale scale (35) is part of a mechanical displacement measuring arrangement.

4. The device according to claim 2, characterized in that the scale scale (35) is part of an electrical displacement measuring arrangement (39).

5. The device according to claim 4, characterized in that the tool positioning device comprise an electrical positioning drive (45) for the stop mandrel (25) which responds to the displacement measuring arrangement.

6. The device according to claim 1, characterized in that the tool positioning device comprises a stepper motor positioning drive for the displacement movement of the stop dome and that the scale means for measuring the displacement distance of the stop dome have a counter counting the steps of the stepper motor positioning drive.

7. Device according to one of claims 1 to 6, characterized in that the scale means (35) at the axial reference position (21) of the tool holder (5) coupled to the holder holder (31) on the

Scale value "zero" can be set.

8. Device according to one of claims 1 to 7, characterized in that the tool positioning device comprises a positioning drive (45) driving the stop mandrel (25) for its adjustment movement and that the positioning drive (45) is assigned a data input device (43) the values for the axial length (L1) of the rotary tool (3) and a desired total length (L) of the rotary tool (3) clamped in the tool holder measured between the free end face (19) of the rotary tool (3) and the axial reference position ( 21) of the tool holder

(5) can be entered.

9. The device according to claim 8, characterized in that the tool positioning device, the positioning drive (45) for an adjustment movement according to the difference of the desired

Total length (L) minus the length (L1) of the rotary tool (3) controls.

10. Device according to one of claims 1 to 9, characterized in that a length measuring device (51) for determining the axial length (21) of the rotary tool (3) is provided.

1 1. Device according to one of claims 1 to 10, characterized in that the heating device is designed as an inductive heating device (1 7) and is combined with the tool positioning device to form a structural unit (47).

12. The device according to claim 1 1, characterized in that the structural unit (47) around a cooling station designed as a further structural unit (57) for tools heated by means of the heating device (17). holder (5) is expandable and that the holder receptacle (31) is movably guided between the two structural units (47, 57).

13. The apparatus according to claim 12, characterized in that the holder receptacle (31) on a linear guide (65, 67) between the two units (47, 57) is displaceable.

14. The apparatus according to claim 13, characterized in that a plurality of holder receptacles (31) are combined on a turntable (61) and the turntable (61) can be displaced between the structural units (47, 57) by means of the linear guide (65, 67).