JP2010207929A - Device for fastening and removing tool by induction heating of tool holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further reduce a magnetic field in an external environment of an induction coil or a device. <P>SOLUTION: The device for inductively heating a sleeve 2 of a tool holder 1 includes a central housing aperture 4 for a shank 5 of a rotary tool retaining the shank 5 of the tool to be fixed in the housing aperture 4 by press-fit, and releasing it upon heating, an induction coil layout having at least one induction coil 6 supplying current for heating the sleeve 2, and an electrically non-conductive or primarily non-conductive focusing arrangement body 11 that is magnetizable and converges a magnetic flux of the induction coil 6 to an end range on the tool side of the sleeve 2. The focusing arrangement body 11 carries an induction mounting body 14 made by an electrically conductive material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an induction heating device for a sleeve portion of a tool holder.

  It is known to shrink the shank of the tool at the sleeve portion of the tool holder, especially for tools such as milling cutters and drills that rotate at high rotational speeds. For this purpose, the sleeve part is heated, for example using an induction coil surrounding the sleeve part, so that the tool shank expands under the influence of heat, i.e. plugs into the receiving opening of the expanding sleeve part. be able to. The outer diameter of the tool shank is somewhat larger than the nominal diameter of the receiving opening, so that the tool is held in the tool holder so that it does not rotate with a press fit after cooling of the sleeve part.

  A suitable induction heating device for this is known, for example, from DE 10102710 A1. This device has an induction coil to which an alternating current is supplied, which can be mounted on the sleeve part of the tool holder and surrounds the tool holder in an annular manner at radial intervals. The magnetic field of the induction coil induces an induced current that heats the sleeve directly in the electrically conductive, magnetizable material of the tool holder. The induction coil extends in the axial direction over at least the engagement length in which the tool shank sinks into the receiving opening, and together with its winding, for example in the region of the front end on the tool side of the sleeve part, with said sleeve part in the axial direction End. The inner circumference of the induction coil is extended at a distance from the sleeve portion so that the same induction coil can be used in a tool holder having a different outer diameter of the sleeve portion in the radial direction.

  The windings of the induction coil are covered by a focusing device array which is magnetizable on its front face and its outer circumference, i.e. made of ferromagnetic or ferrimagnetic material, and the high magnetic conductivity of said material relative to air makes the magnetic flux essentially Are gathered on the mantle. The magnetizable material of the focusing device array is electrically non-conductive to prevent the focusing device jacket from being inductively heated. The region of the converging device mantle adjacent to the tool side end of the sleeve part is formed as an annular converging device body which sits axially directly on the tool side front surface of the sleeve part. The meaning and purpose of such a focusing device body is to locate and introduce a magnetic field into the sleeve part, where it acts efficiently, and at the same time, the tool shank protruding from the sleeve part is inductively heated by stray magnetic field components. The tool shank is similarly expanded and undesired. Such a focusing device body is preferably formed as a shielding collar, for example as described in DE 10102710A1. This shielding collar first captures the majority of the magnetic field lines that exit into the external space. The shielding collar thereby prevents the protruding tool shank from being heated in an efficient manner.

  Nevertheless, even in such an arrangement there is still a stray field that can be measured in the induction coil or in the external environment of the entire device. Such stray fields can also interfere with the primary function of internal and external contractions in the main number of applications.

  In recent years, an increasing interest in the theme "stray electric field" has been confirmed in addition to the area that has had a special interest in the past.

German Patent Application Publication No. 10102710

  The object of the present invention is to continue to reduce the magnetic field in the external environment of the induction coil or device.

  This problem is solved by the features of the main part of claim 1. The focusing device body carries an inductive mount made of a material which is indirectly or directly electrically conductive and preferably magnetically nonconductive. In this induction mount, the magnetic field of the induction coil or the induction coil extending in the external environment of the device overlaps and thus a magnetic field that partially attenuates is generated. In this way (usually additional) active magnetic shielding is achieved. Compared to a shield achieved by a pole piece or the like made of a material that is electrically non-conductive and magnetically conductive, such as ferrite, and can therefore also be referred to as “passive shielding”.

  According to claim 2, this is that the inductive mount is flowed by a part of the magnetic field that extends out of the focusing device body for each section so that current is induced in the inductive mount itself. In short, the magnetic field to be attenuated automatically causes a reverse magnetic field to be generated starting from the induction mount and acting while being attenuated in the external environment of the coil.

  Preferably, the guide mount is configured as a ring that is normally closed in the circumferential direction. This ring ensures a good shielding, since the magnetic field lines of the high-frequency magnetic field are actually completely captured there by the method and no possibility of disturbing the action of the inductive mounting according to the invention is found.

  The embodiment of the copper induction mount is particularly preferred. In so far, it has been found that it clearly exerts an excellent effect on any other material (eg aluminum) that seems to be equivalent at first glance in the application according to the invention.

  The guide mount is preferably formed so that the guide mount has a folded cross-section of the ring. The guiding attachment thereby extends radially outward from the focusing device body through the focusing device and from the focusing device body when the focusing device body is installed under its horizontal alignment. Stretch upward relative to the horizontal direction with a slight inclination (preferably between 10 and 20 degrees). In this way, the guiding mount forms a kind of obstruction that is effectively pierced by the magnetic field lines with respect to the essential part of the magnetic field lines that otherwise have a tendency to bypass the focusing device body first. In other words, the magnetic field lines are used very efficiently to generate a corresponding reverse magnetic field in the induction mount along with the eddy currents.

  Preferably, it is considered that the focusing device body plugs into the retaining ring on its radially outer side. This is used to position the focusing device body relative to the magnetic coil array. The retaining ring also holds the guide mounting body on the focusing device body in a position at the same time, preferably in a position where the focusing device body and the guide mounting body are in direct flat contact with each other. This allows heat to flow quickly from the induction mount to the focusing device body on a scale to be noted. In particular, with this arrangement, the focusing device body and its corresponding guiding body are always fixedly connected to each other and, if necessary, an alternative focusing device body and another matching mounting method. Since it can be exchanged with a corresponding unit consisting of a body, handling is also simplified, and the user does not have to think about which guide mounting body is assigned to which focusing device body. A very efficient magnetic cooperation between the focusing device body and the guiding mount, i.e. a fully reinforced shielding area, is guaranteed, especially when the focusing device body and the guiding mount are in direct contact with each other flat. Has been.

  Within the framework of an advantageous development, it is conceivable to construct the retaining ring as a plastic ring. The fact that the plastic ring is most simply used can take into account the fact that a relative movement constrained by thermal expansion occurs between the focusing device body and the guide mount. This is almost unavoidable because the induction mounting body is heated by the eddy current generated directly in the induction mounting body, unlike the focusing apparatus main body.

  This retaining ring may of course be configured as a ceramic ring in principle. That is, this is the case when the ceramic ring surrounds the focusing device body and the induction mounting body with some play so that the ceramic ring is not ruptured by thermal expansion of the induction mounting body or the focusing device body. However, considering this, ceramic retaining rings clearly present manufacturing and tolerance issues rather than the preferred plastic retaining ring.

  If the retaining ring is a plastic ring, the entire unit consisting of the guide mounting body, the focusing device body and the plastic ring is ideally loaded into a plastic injection molding machine where the focusing device body and the guide mounting body together correspond. And after being cured, it is manufactured by injection molding with plastic forming a retaining ring.

  The holding ring is preferably made of a heat-resistant plastic having shape stability within a range in which the holding function is guaranteed up to 150 ° C., ideally even at a temperature of 120 ° C. or higher. The production of a retaining ring made of a heat-resistant plastic allows a plurality of internal and external contractions to be carried out in sequence without pause. In addition, the unit comprising the focusing device main body and the holding ring does not malfunction because the induction mounting body is heated until at least the induction mounting body thermally damages the plastic of the holding ring. The plastics considered for the intended use include in particular PI or PTFE plastics.

  In one particularly preferred embodiment of the framework, the retaining ring plastic is entirely or partly of the guiding attachment, and especially when the user wants to remove the unit comprising the guiding attachment, the focusing device body and the retaining ring from the device. It is also included in the outer peripheral area where the user casually touches the hand. In this way, the user is not in direct contact with the superior heat conductive surface of the induction mount, thereby reducing the risk of the user being burned with a suddenly heated induction mount.

  The induction mount is ideally provided or covered with an at least partially intermittent plastic contact protector. This intermittent contact protector is a part, preferably made of a heat-resistant plastic, which has a large number of penetrations, ie "intermittent", at narrow intervals (eg plastic or nylon as described above). Air or coolant that cools (flows by blast or convection) through the penetration is required to flow directly into the metal surface of the induction mount, so that the induction mount is efficient despite contact protection Can be cooled to. Although narrowly spaced, each penetrating portion is small compared to the web between the penetrating portions, so that even when the user's skin touches the induction fitting heated to about 80 ° C., the penetrating portion is essentially Through direct contact with the metal surface of the induction mount, there is no burn due to the high thermal conductivity of the surface. Since it depends on the individual case, it is not possible to provide a concrete indication of how large and how narrow the penetrations need to be spaced in each case. However, those skilled in the art should be able to calculate this for a specific individual case with a few few experiments, and should generally prevent as little air or coolant inflow to the metal surface of the induction fitting as possible. As a result, the metal surface takes into account the condition that it is only covered as long as sufficient contact protection is required for safety. The contact protector can be configured as an integrated part of the retaining ring or as an independent member. The intermittent contact protector is ideally formed as a kind of cage that is at least partially closed. That is, it is configured as a cage that is at best locally in contact with the surface of the induction mount and whose “grid portion” is essentially spaced from the surface of the induction mount. Alternatively, the contact protector may abut directly on the surface of the induction mount, for example in the form of a mesh or grid.

  The induction fixture is ideally implemented in direct succession to the final temperature of the induction ring, in which each one cold tool holder is heated, until the tool incorporated in the tool holder can be used and removed again. The induction mount is formed so that the induction mount has a large heat capacity or mass that is 100 ° C. or less, or even 80 ° C. or less, even after multiple shrinkage cycles. This is decisive because the current induced therein in the inductive fixture generates a considerable amount of heat that can be incompletely delivered to the surrounding outside air in a short time. Nevertheless, the derivative must not be heated arbitrarily. The above method helps.

  Hereinafter, the present invention will be described in more detail with reference to the drawings in which other details of the operation and advantages of the present invention become apparent.

It is an axial direction longitudinal cross-sectional view of the apparatus which concerns on this invention for induction heating the tool holder provided with a disk-shaped pole piece in the tool side edge part of a tool holder. It is an axial direction longitudinal cross-sectional view of the unit which consists of a focusing apparatus main body, a guidance attachment body, and a holding ring. It is a half sectional view of the 2nd example of another method.

  Before describing in detail the inductive mount according to the present invention, the function of the device shown in FIG.

  A tool holder 1 is identified which is at least electrically conductive, but in this case made of a magnetically conductive material, for example steel. The tool holder has a sleeve portion 2 at the other end. The sleeve part 2 can be inserted into the receiving opening 4 together with its shank 5 concentrically with the rotating shaft 3 of the tool holder, and the receiving opening for a rotary tool not shown in detail, for example a drill, a milling cutter or a friction tool 4 is also included.

  The outer diameter of the shank 5 is somewhat larger than the free nominal diameter of the receiving opening 4, and as a result, the shank 5 is held in the sleeve part 2 with a press fit, whereby the necessary torque is transmitted to the rotary tool. be able to. In order to allow the tool shank 5 to be inserted into or removed from the tool holder 1, the sleeve portion 2 is expanded in diameter by heating. This heating is performed by using an induction coil 6 that is placed on the sleeve portion 2 and concentrically surrounds at a radial interval by using the side surface thereof. This is supplied with an alternating current or a pulsed direct current with a frequency of eg 5-20 kHz. The magnetic flux generated by the approximately cylindrical winding 7 induces eddy currents in the sleeve portion 2. This enlarges the receiving opening 4 sufficiently to heat the sleeve part 2 in a relatively short time and thereby allow the tool shank to be inserted or withdrawn.

  The induction coil 6 has a coil body 8 made of heat-resistant plastic or ceramic that is placed inside and to which a multilayer winding 7 is attached. The front surface of the winding 7 which is spaced from the tool in the outer circumference and in the axial direction is made of a magnetically conductive and electrically nonconductive material which bundles and concentrates the magnetic flux on the yoke array 9 in the circumferential region of the winding 7. The single or multi-body yoke array 9 is covered.

  The winding 7 with the yoke arrangement 9 essentially extends over the entire length of the receiving opening 4 or the sleeve part 2 designated for receiving the tool shank 5.

  The part of the tool shank 5 which projects the magnetic flux from the yoke arrangement 9 which protrudes somewhat in the axial direction through the winding 7 on the side, preferably toward the front surface 10 of the sleeve part 2 and simultaneously through the sleeve part 2 is shielded. In order to protect against induction heating, a focusing device main body 11 that influences the magnetic field emitted from the yoke array 9 is incorporated in the front surface SF of the coil. As shown in FIG. 1, the focusing device body 11 is preferably formed in the form of a shielding collar. The focusing device body consists of a magnetically conductive material that collects the magnetic flux, but in essence this material is not electrically conductive and therefore is not heated as noted under the influence of a magnetic field.

  The focusing device main body 11 formed in this way extends entirely from the yoke array 9 with an interval. The yoke array 9 does not extend over the tool-side front surface of the winding 7 in the illustrated embodiment, but merely projects slightly above the front surface, but it can also cover the coil if desired. The focusing device body has a flat mounting surface 12 on which the focusing device body is mounted in a plane on the front surface of the ring-shaped sleeve portion 2. .

  The focusing device body 11 comprises a retaining ring 13 made of a magnetically non-conductive and electrically non-conductive material, especially plastic, that is resistant to higher temperatures. The focusing device body 11 is fixed relatively to the induction coil 6 using the holding ring 13. However, the focusing device body is fixed so that it can be exchanged for one selected from a focusing device body (not shown) that is dimensioned somewhat differently as required. In this way, the focusing device body 11 causes a specific axial positioning of the sleeve part 2 (of the tool holder) used relative to the induction coil 6. Further, the same induction coil 6 can be exchanged for various sleeve portions 2 with a tool holder in order to fit the focusing device body.

  The annular gap remaining between the yoke arrangement 9 and the focusing device body 11 here configured in the form of a shielding collar increases the resistance in the magnetic circuit of the induction coil 6. The focusing device body 11 nevertheless allows the magnetic flux to be concentrated on the sleeve part 2 without stray fields in the area of the tool shank 5 due to its aspect as a shielding collar. By this method, the sleeve portion 2 can be induction-heated, and the tool shank 5 is not excessively heated.

  The focusing device body 11 now supports the induction mounting body 14 on the outside spaced from the induction coil 6 according to the invention. Unlike the focusing device body, this induction mount is made of a material that is electrically conductive but magnetically non-conductive.

  The guide attachment 14 is in direct contact with the focusing device main body 11 in a large area. The guide mount and the focusing device body now contact essentially along the entire upper plane of the focusing device body. The guide mount 14 can deliver part of the thermal energy generated in the guide mount to the focusing device body very quickly if necessary by this method, thereby preventing overheating of the guide mount that may occur. The

  The guide attachment 14 projects radially outward from the focusing device body. The guide mounting is then preferably inclined upwards (for example at an angle α of 10 to 20 degrees with respect to the horizontal direction) and is shown in FIGS. 1 and 2. Accordingly, the guide attachment body 14 can be limited to a circular ring that is folded upward together with its outer periphery. The guide mount forms a collar which projects outwardly onto the focusing device body in this way. This collar would otherwise be forced through by the essential part of the magnetic field lines that would first bypass the focusing device body and finally tend to enter the focusing device body from a region higher than one of the axes 3. Form a kind of obstruction.

  Based on this, an eddy current is inevitably generated in the induction mounting body 14 to form a magnetic field, a kind of reverse magnetic field, on the induction mounting body side. In other words, the magnetic field that is attenuated in the external environment of the coil 9 automatically generates a reverse magnetic field that starts from the induction mounting body 14 and acts while being attenuated.

  The guide attachment is here configured as a copper ring closed in the circumferential direction. In principle, for example, an embodiment as an aluminum ring is also possible. However, it has been found that the embodiment as a copper ring provides essentially more efficient action to the induction fitting for this application in this case, or essentially results in less heating of the induction fitting.

  The focusing device body and the guide mount are inserted into the common retaining ring 13 already briefly described above. The retaining ring 13 is made of a plastic that is highly heat-resistant and injection molded on the focusing device body 11 and the guide mounting body 14. The retaining ring plastic also includes an induction mount in the region of its maximum outer diameter and is in contact with the surface of the induction mount 14 where the user is directly exposed to hot and inevitably good heat transfer. To prevent.

  FIG. 3 shows a half-sectional view of another embodiment of the present invention.

  In this embodiment, the focusing device body 11 itself is not provided with a guide mounting body, but here also directly on the coil arrangement 9 or the coil housing (especially the area of the front face of the coil 6 facing the end of the sleeve part). The provision of the colored derivative 14a distinguishes it from the embodiment described with reference to FIGS. That is, the above aspect applies literally unless a three-dimensional feature that does not correspond to FIG. 3 of the guide attachment is mentioned here.

  The functional principle of the derivative 14a is also the same as that described for the derivative in the form of the induction mounting body 14 described above. The derivative 14a is flowed by the magnetic field of the coil 6, thereby inducing a current in the derivative. This current generates a reverse magnetic field that partially attenuates or deflects the main magnetic field, and as a result it can also be referred to as active shielding.

  Furthermore, the leg F holding the collar-side main part H of the derivative 14a is preferably not made of the same electrically conductive and magnetically non-conductive material as the collar-side main part H, preferably a plastic material. Note that it consists of Thereby, the thermal load of the derivative is essentially reduced compared to the case where the legs F are made from an electrically conductive material.

  The fixing or holding of the derivative independent of the focusing device body is particularly useful for systems with adjustable coils and / or adjustable focusing device bodies that do not require different sleeve diameters to modify the system against contraction. There is substantial significance in practice.

  Furthermore, it is borne in mind that an equally effective active shielding element can also be attached, for example to the circumference of the coil, for example to shield the operating button of the coil.

  Finally, it is further confirmed that a guide mount of the type described herein works in conjunction with a focusing device body which is of course formed non-exclusively as a shielding collar.

  The present invention can be advantageously used as an induction heating device for a sleeve of a tool holder.

DESCRIPTION OF SYMBOLS 1 Tool holder, 2 Sleeve part, 3 Tool holder rotating shaft, 4 Accommodating opening part, 5 Tool shank, 6 Inductive coil, 7 Inductive coil winding, 8 Coil body, 9 Yoke arrangement, 10 Sleeve front, 11 Focusing device main body, 12 mounting surface, 13 holding ring, 14 induction mounting body, 14a derivative, SF = front surface of coil, F = leg, α = tilt angle.

Claims (14)

Tool comprising a central receiving opening (4) for the rotating tool shank (5), which holds the tool shank (5) fixed in the receiving opening (4) with a press fit and is released upon heating. In a device for clamping and detaching a tool having a tool shank in which the sleeve part (2) of the holder (1) is inductively heated, at least one capable of supplying an electric current for heating the sleeve part (2) An induction coil arrangement comprising an induction coil (6) and a magnetically conductive and electrically non-conductive or essence that concentrates the magnetic flux of the induction coil (6) in the region of the end of the sleeve part (2) on the tool side A non-conductive focusing device body (11),
A device characterized in that the focusing device body (11) carries an induction mounting (14) made of an electrically conductive material.   The focusing apparatus body is configured to flow through the induction mounting body (14) so that a current is induced in the induction mounting body (14) by a part of the magnetic field extending outside the focusing apparatus body (11). A reverse magnetic field over which the magnetic field of the coil (6) is superposed so that at least a local decrease of the magnetic field of the coil (6) is provided, wherein the magnetic field of the coil (6) flows entirely through the external environment of the device. 2. The device according to claim 1, characterized in that the induction fitting (14) is positioned and spatially arranged such that is generated by an electric current induced in the induction fitting.   Device according to claim 1 or 2, characterized in that the guide mount (14) is configured as a ring which is electrically closed itself in the circumferential direction.   Device according to any of the preceding claims, characterized in that the induction mounting body (14) is made of copper.   Device according to any of the preceding claims, characterized in that the guide attachment (14) has a folded ring cross-section.   6. A device according to claim 3 or 5, characterized in that the cross section of the ring is inclined relative to the horizontal direction upwards, preferably at an angle ([alpha]) of 10 to 20 degrees.   In order for the focusing device body (11) to be positioned on the magnetic coil array radially outwardly, the guiding attachment (14) is simultaneously held in a position relative to the focusing device body (11), preferably the focusing device body ( Device according to any one of the preceding claims, characterized in that 11) and the guide fitting (14) are inserted into a retaining ring (13) which holds them in a position in direct direct contact with each other.   8. Device according to claim 7, characterized in that the retaining ring (13) is a plastic ring formed by at least partial injection molding of the converging device body and the guide mounting body in common.   The plastic of the retaining ring (13) includes the induction mount (14) in whole or in part, so that the plastic reduces the risk of a user being burned with the heated induction mount. The apparatus according to claim 8.   6 times the final temperature of the induction fixture (14), in which each one cold tool holder is heated, is carried out directly in succession to each other until the tool incorporated in the tool holder can be used or removed. 10. An apparatus according to any one of the preceding claims, characterized in that the induction mount (14) has a large heat capacity or mass such that it is on average not more than 80C even after cycling.   In a yoke arrangement (9) of magnetizable, electrically non-conductive or essentially non-conductive material, said yoke arrangement (9) is arranged in the region of the front face of the coil (6) if necessary. A magnetic circuit which is at least partially closed together with the sleeve part (2) including the focusing device body (11) is formed around the induction coil and is made of an electrically conductive material. Device according to any of the preceding claims, characterized by a yoke arrangement in which the derivative (14b) is incorporated.   12. Device according to claim 11, characterized in that the derivative (14b) is arranged in the region of the front face of the coil facing the end of the sleeve part (2).   A reverse magnetic field that superimposes the magnetic field of the coil (6) is generated by the current induced in the derivative so that the derivative (14b) produces at least a local decrease in the magnetic field of the coil that generally flows through the external environment of the device. 13. A device according to claim 11 or 12, characterized in that the derivative is positioned and spatially configured. 14. Device according to claim 1, characterized in that the derivative (14, 14b) is formed from a magnetically non-conductive material.

Images