Quick-change chuck for a hole saw and hole saw arrangement with a quick-change chuck and a hole saw

Description

[0001] The invention relates to a quick-change chuck for connecting a hole saw to a drive, e.g., a drill. State of the art

[0002] In particular, the invention relates to a quick-change chuck rotatable about a rotation axis for releasably holding a hole saw, which extends along the rotation axis from a rear or proximal drive end, designed for releasable connection to a drive, to a front or distal connection end, designed for releasable connection to the hole saw.

[0003] In this description, the directional terms distal and proximal refer to a drive that can be connected to the drive end of the hole saw assembly. Proximal is oriented toward this drive at the drive end, and distal is oriented away from this drive.

[0004] The quick-change chuck comprises a base body which is designed to accommodate at least one clamping jaw so as to be relatively movable and adjustable in relation to the axis of rotation. At the connecting end, thread segments are provided around the axis of rotation to form an external thread, of which at least one thread segment is formed on the relatively movable clamping jaw. A spring is arranged between the clamping jaw and the base body such that the at least one thread segment can be moved against a spring force of the spring from an engaged position located radially further outwards into a release position located radially further inwards in relation to this engaged position. In the engaged position, the external thread engages in a corresponding central threaded opening in a saw base of the hole saw and thus connects the quick-change chuck to the hole saw in a rotationally fixed manner.Furthermore, drive pins can be formed between the connecting end and the hole saw, which, when installed, engage in correspondingly shaped holes in a saw base of the hole saw. A center drill extending along the rotation axis can also be removably inserted into the chuck, preferably via a grub screw that can be screwed in from the side.

[0005] Abstractly, the invention relates to a device for easily coupling and changing a hole saw with a drive. Such quick-change couplings are available in numerous different designs for industrial and professional applications, with hole saws of different sizes and diameters being used on the hole saw. Hole saws are typically box-like or cup-shaped, with a circular-cylindrical saw rim that has a sawing structure at the free front end and can be connected to a support or has a holder or support plate at a rear end.

[0006] Furthermore, the invention relates to a hole saw arrangement comprising a quick-change chuck, a hole saw which can be connected to the chuck in a detachable but non-rotatable manner, and a center drill which can be connected to the chuck in a detachable but non-rotatable manner.

[0007] A generic quick-change chuck and a hole saw arrangement of the type mentioned are known, for example, from EP 3 429 789 B1 or WO 2019 / 090123 A1.

[0008] DE 20 2013 006 690 U1 discloses a different type of chuck, in which the hole saw is screwed to a connecting piece that can be inserted into a shank and secured therein via a ball catch. By axially displacing a locking sleeve that surrounds the ball catch on the outside, the ball catch can be released, allowing the connecting piece with the hole saw to be removed from the shank. Disadvantages of the state of the art

[0009] Pressing the clamping jaw together to release the hole saw, i.e. to move the clamping jaw from the engagement position to the release position, requires a lot of force from the user and is therefore not always easy for the user to perform.

[0010] Furthermore, various problems can arise due to the non-rotationally symmetrical design and the resulting uneven weight distribution of the quick-change chuck around the rotation axis. These problems are related to the fact that the clamping jaw moves out of the center, particularly at higher speeds, due to the imbalance, i.e. is offset from the center to the outside, whereby the clamping jaw can break off and cause injuries.

[0011] These problems occur particularly during the drilling process of a so-called "interrupted cut", in which two holes are drilled whose bore diameters interlock. The hole saw does not always engage with material when drilling the second hole, so that an imbalance occurs, which causes the hole saw to lose its rotational movement and is therefore dangerous.

[0012] Similar problems occur when drilling at an angle in a surface, where one section of the hole saw also penetrates the material earlier than another.

[0013] Here too, the resulting imbalance can cause the clamping jaw and thus the hole saw to come loose unintentionally.

[0014] A further problem with the prior art is that the two thread segments are only pressed together in one longitudinal direction, and the thread diameter is therefore only reduced in the longitudinal direction. The side surfaces of the threads are flattened perpendicular to the direction in which the thread segments are pressed together, so that when pressed together longitudinally, the external thread no longer engages the internal thread in the transverse direction. This means that the hole saw only contacts the two longitudinally adjustable internal thread segments within an angular range of approximately 30 to 40 degrees, meaning that a large portion of the thread segment cannot be used to attach the hole saw to the base body, which reduces durability. Task

[0015] Based on the aforementioned prior art, the invention is based on the object of at least partially avoiding the disadvantages indicated and, in particular, of providing a quick-change chuck in which changing the hole saw is special. invention

[0016] This problem is already solved by the features of independent claim 1. Advantageous further developments are described in the subclaims.

[0017] According to the invention, this object is achieved in a quick-change chuck of the type mentioned at the outset by means of a clamping ring which is rotatable about the axis of rotation and is further designed to move the at least one clamping jaw from the engaged position into the release position upon rotation. This clamping ring thus forms a linear gear, converting a rotational movement into a translational movement of the clamping jaw. The user therefore only has to turn the clamping ring to release the at least one clamping jaw and move it into the release position, which is considerably simpler than the pressing together required in the prior art. For this purpose, a link drive is also provided between the clamping ring and at least one clamping jaw, by which means that the components each comprise one from the group of the guide curve and guide pins engaging in and guided by the guide cam.The guide curve thus guides the guide pin along one or both longitudinal sides of the guide curves when the clamping ring rotates around the rotation axis. The guide curve is geometrically designed such that when the clamping ring rotates, the at least one clamping jaw is adjusted by the desired amount, which is preferably only 1 to 5 mm, in particular 1 to 3 mm, and particularly preferably 1.4 to 1.5 mm. The guide curve is preferably designed as a curved section, which is in particular shaped like a circular segment.

[0018] For this purpose, guide curves are provided in the clamping ring or in the main clamping ring plane of the clamping ring, which extends transversely to the rotation axis in the installed position, with a front curve end and a rear curve end, into which a complementarily designed guide pin, i.e. in particular a pin connected to the distal front side of the clamping jaw, in particular a pin inserted into the front side of the chip jaw, engages on the other joining partner and is guided relatively movably in the guide curve when the clamping ring is opened and closed. The center of the front curve end lies on a center circle of the guide curve, an imaginary circle which extends around the rotation axis through the center of the guide curve.The rear end of the curve, however, is offset radially inwards or outwards in relation to this center circle, so that the jaw or guide pin guided in the guide curve is moved radially outwards or inwards along the outer edge of the guide curve when the clamping ring rotates.

[0019] The guide curve thus forms a guide slot, i.e. a surface enclosing it, defined in particular by the clamping ring, in which a groove-like guide is provided for the guide pin, which at the rear end is further away from the central axis of rotation than at the front end, i.e. deviates from the circular path.

[0020] Preferably, the guide slot is designed in such a way that the clamping jaw is moved into the radially outward engagement position by the force of the spring.

[0021] Preferably, the link drive is designed in such a way that when a relative movement is carried out between the guide curve and the guide pin, the guide pin is guided along the radial outer edge, whereby the clamping jaw is displaced radially in the base body because the radial distance of the curve start of the guide curve to the axis of rotation is different than the distance of the curve end, whereby the guide curve moves in the direction of rotation either towards the axis of rotation or away from it.

[0022] According to the invention, the design of the guide curve on the clamping ring and according to the invention the design of the guide pin on the clamping jaw.

[0023] The guide pin can either be provided in one piece on the clamping jaw, i.e. be molded onto it, or be designed to be insertable into it, e.g. as a pin that can be inserted into a corresponding receiving opening.

[0024] In the particularly preferred embodiment, the guide curve is designed as an arcuate curve segment, which extends as a curved section on an imaginary circle that encloses the axis of rotation and runs centrally through the guide curve. However, to achieve the necessary offset, the front and rear ends of the curve are radially offset from this imaginary circle, thus resulting in a radial displacement of the guide pin guided in the guide curve upon rotation of the clamping ring.

[0025] The at least one clamping jaw is seated radially movable in a geometrically complementary clamping jaw receptacle on the base body, which is designed to be as rotationally symmetrical as possible, in particular designed as a recess or the like, in which the clamping jaw is seated and guided radially movable, i.e. can be moved back and forth radially in relation to the axis of rotation.

[0026] The clamping jaw can comprise an insert section facing the base body in the installed position, which insert section sits relatively movably in the corresponding clamping jaw receptacle of the base body. A clamping section is formed on this insert section, preferably integrally formed, which, in the installed position, extends parallel to the axis of rotation, preferably partially enclosing it in the proximal direction, i.e., upwards. The hole saw, with the hole saw base and the central threaded opening provided therein with an internal thread, can be placed onto this clamping section.

[0027] Preferably, the insert and clamping sections extend at a right angle to each other, i.e. they enclose a right angle between them.

[0028] In the preferred embodiment, which is designed for fastening hole saws with different outer diameters and thus different inner diameters of the central threaded openings provided in the saw base, the clamping section has a distally extending hollow cylinder section adjacent to the insert section, which preferably has no external thread and has a slightly larger outer diameter than a threaded section adjoining this hollow cylinder section further distally. A radially outwardly projecting separating flange is preferably formed between the hollow cylinder section thus formed, which is lower in the installed position, and the upper threaded section with a smaller outer diameter.

[0029] For smaller hole saws, an adapter ring acting as a spacer element can be placed on the hollow cylinder or clamping section of the clamping jaw on which the saw base of the hole saw sits, so that the hole saws with a central thread diameter of 9 / 16 inch can be connected to the upper thread segment.

[0030] For larger hole saws with correspondingly larger central threaded openings, however, this adapter ring can be removed so that these hole saws, which preferably have an inner diameter of the central threaded opening of 5 / 8 inch, are clamped with the lower hollow cylinder section of the clamping section of the clamping jaw.

[0031] Preferably, a spring is arranged on the radial inside between the clamping jaw and a central region of the base body, which spring presses the clamping jaw radially outwards into the engaged position.

[0032] The clamping ring, which can be rotated about the axis of rotation, is thus arranged on the base body, preferably on the distal end, which is referred to here as the end facing away from the drive, whereby the end facing the drive, i.e. the drive end, represents the proximal end of the chuck. A simple rotation of the clamping ring about the axis of rotation thus brings about a linear adjustment of the at least one clamping jaw from the engaged position located further outwards in relation to the axis of rotation into the released position located further radially inwards in relation to the engaged position, whereby the threaded segments connected to the clamping jaws or formed on them move towards the axis of rotation and towards one another when loosening and away from the axis of rotation and from one another when tightening.

[0033] The clamping ring is preferably arranged at the front distal end of the base body, e.g., placed on the front side of the chuck. To guide the clamping ring on the chuck, clamping ring positioning means acting as alignment means are formed between the two joining partners (clamping ring, chuck). These clamping ring positioning means realize a coaxial arrangement of the clamping ring on the chuck, but at the same time also enable easy rotation of the clamping ring relative to the then stationary chuck. These clamping ring positioning means can, for example, comprise an outer edge or flange that encompasses the outer edge of the preferably circular base body, so that the clamping ring sits on the base body like a cover with an outer flange or shoulder.Preferably, these clamping ring positioning means comprise a flange extending in particular transversely to the plane defined by the clamping ring (main clamping ring plane) or a flange which, when placed radially on the outside of the clamping chuck, encompasses the outer peripheral edge of the clamping chuck.

[0034] Particularly preferably, the linear gear is designed such that during rotation the movement of the at least one clamping jaw and the thread segments formed on it move from the engagement position to the release position and vice versa, i.e. the at least one clamping jaw is pulled radially towards the axis of rotation or pushed away from it when the clamping ring is rotated, in particular guided in the clamping jaw receptacle in the base body which is designed correspondingly to receive the clamping jaw.

[0035] The quick-change chuck can have a locking mechanism to prevent accidental release of the clamping jaws.

[0036] Preferably, this locking device has a radially outwardly projecting extension, projection, or the like at the front end of the jaw retraction curve, which implements a locking force that must first be overcome for release, into which the guide pin thus engages in the engaged position. Preferably, after overcoming this initial locking force, the spring force automatically opens the at least one clamping jaw, so that the latter is designed to then automatically move into the engaged or locked position. Due to the spring force, the corresponding guide pin only has to be moved slightly radially inward, so that after overcoming this locking force, the clamping ring even moves automatically into the engaged position due to the spring force.

[0037] A particularly precise arrangement of the clamping ring in relation to the base body can be achieved in that the clamping ring positioning means comprise a lid or a cover which is placed on the distal end of the clamping ring and thus surrounds or encloses the clamping ring on both sides in the installed position with the base body.

[0038] Additional clamping ring positioning means can be formed between the cover and the clamping ring, e.g., in the form of complementary pins that engage corresponding rotary cams or guide cams. Preferably, curved sections or curved segments are formed in a clamping ring main plane of the clamping ring on an imaginary circle around the rotation axis. These curved sections or curved segments form one or more rotary cams in which fastening screws are guided. These screws connect the cover to the chuck and penetrate the clamping ring main plane of the clamping ring, thus acting as rotary cams.

[0039] The fastening screws are preferably designed as countersunk head screws which are screwed into the top of the cover.

[0040] Particularly preferably, three countersunk screws are screwed onto the surface of the cover, offset by approximately 120 degrees to each other, through the clamping ring into the base body, which accommodates the clamping jaws in a relatively movable manner.

[0041] To prevent the cover from being screwed too tightly onto the clamping ring, spacer bushings can be provided between the base body with the clamping jaw accommodated therein and the cover. These spacer bushings are preferably made of steel and enclose the screws or are penetrated by the screws and are guided in the directors of the clamping ring. Preferably, three screws are provided, which engage in corresponding rotary cams of the clamping ring in the installed position and are particularly preferably provided with corresponding spacer bushings.

[0042] A particularly harmonious and easily adjustable embodiment, which thus avoids imbalances and the disadvantages outlined at the beginning particularly well, three clamping jaws are provided in the base body, in particular three are accommodated in the chuck at 120 degrees to each other with the central longitudinal axis radially extending from the central axis of rotation, for which purpose three corresponding clamping jaw receptacles are formed in the base body, extending in a star shape from a central area of ​​the base body, in which the clamping jaws are accommodated or seated in a radially displaceable manner.

[0043] Each clamping jaw has a circular thread segment on its distal upper side, so that the three thread segments together form the circular-cylindrical threaded stud with the external thread for fastening the complementary internal thread in a central threaded opening, i.e., an opening with an internal thread in the center of the saw base. Each thread segment is thus provided with a threaded section, so that the three clamping jaws, arranged 120 degrees apart from each other, form the circumferential surface of the external thread with interruptions, on which the hole saw with the internal thread can be fastened in the saw base.

[0044] Preferably, a guide pin is provided on the distally oriented upper side of each of the clamping jaws, in particular inserted into the clamping jaw, which engages in the complementary guide curve on the clamping ring and is guided by the guide curve during rotation of the clamping ring.

[0045] Since the three clamping jaws are adjusted synchronously, the clamping ring can also be called a synchronous ring in this case.

[0046] The quick-change chuck, sometimes simply referred to as a "collet chuck," is designed at its rear end for a rotationally fixed and preferably detachable connection to a drive, e.g., a drill chuck of a drill or cordless screwdriver, for which purpose the chuck preferably has a hexagon extending along the rotation axis. At the front end, which faces away from the drive end, the chuck can be detachably connected to a hole saw.

[0047] The hole saw comprises a circular saw rim with a saw blade at the front end and a saw base extending perpendicular to the saw blade at the rear end, giving the hole saw a quasi-cup-shaped design. A threaded opening is provided in the center of this saw base, which can be removably connected to the external thread of the chuck.

[0048] To better avoid a relative movement between the hole saw and the quick-change chuck, two or four driving pins extending parallel and offset from the rotation axis are preferably provided on the distal front side of the quick-change chuck, which engage in correspondingly designed pin openings in the saw base of the hole saw.

[0049] The detachable fastening of the centering drill within the base body along the central axis of rotation is preferably carried out via a grub screw that can be screwed into the base body at the side.

[0050] To adapt to different sized hole saws with different sized central threaded openings, preferably ½ and 5 / 8 inch, an adapter ring can be placed on the keyless chuck distal to the cover. This adapter ring allows smaller hole saws, which usually have a 9 / 16 inch internal thread, to sit on and be held in place by the upper threaded section of the clamping jaws, i.e. the upper section of the clamping section of a clamping jaw, which has the external thread or thread segment on the radial outside. The adapter ring therefore encloses the lower hollow cylinder section of the hollow cylinder section of one or more clamping jaws up to the limit flange, which separates the lower and somewhat wider hollow cylinder section from the upper threaded segment, which has a smaller external diameter and the external thread segment than the hollow cylinder section.

[0051] However, if larger hole saws with an outer diameter of 32 mm or more are used, they typically have a 5 / 8-inch internal thread, which sits on the slightly wider lower hollow cylinder section of the clamping jaws and can be clamped to them. Therefore, no intermediate adapter ring is required, allowing the larger hole saws with an outer diameter greater than 32 mm to sit directly on the distal connection end of the quick-change chuck or the drive pin.

[0052] In the following detailed description of the figures, reference is made to the accompanying drawings, which form a part of this specification, and in which, by way of illustration, specific embodiments are shown with which the invention may be practiced. In this regard, directional terminology such as "top," "bottom," "front," "back," "forward," "rearward," etc., is used with reference to the orientations of the described figure(s). Since components of embodiments can be positioned in a number of different orientations, the directional terminology is for illustrative purposes and is in no way limiting.

[0053] It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention as defined by the claims. The following detailed description is not to be taken in a limiting sense. Throughout this description, the terms "connected," "attached," and "integrated" are used to describe both direct and indirect connection, direct or indirect connection, and direct or indirect integration.

[0054] Unless otherwise stated, the indefinite article and the definite article do not refer solely to a single component, but should be understood as "at least one." The terminology includes the aforementioned words, variations thereof, and similar meanings. Furthermore, it should be understood that the terms "about," "substantially," and similar terms in connection with the dimensions and a characteristic of a component of the invention do not describe the described dimension and characteristic as a strict limit or parameter and do not exclude minor variations thereof that are functionally similar. At a minimum, descriptions containing numerical parameters also include variations of these parameters according to mathematical and manufacturing principles in the prior art, e.g., rounding, deviations, and other systematic errors, manufacturing tolerances, etc.

[0055] In the figures, identical or similar elements are provided with identical reference symbols where appropriate. Reference symbol lines are lines that connect the reference symbol to the respective part.

[0056] An arrow, on the other hand, that does not touch any part refers to the entire entity at which it is aimed.

[0057] The representations in the figures are not necessarily to scale. Certain areas may be exaggerated to illustrate details. Furthermore, the drawings may be simplistic and may not include every detail that may be present in the actual design.

[0058] Identical reference numerals in the figures refer to identical components or features. All features of the respective embodiments are disclosed independently and independently of other features of the respective embodiment. The embodiments shown and described are not to be understood as an exhaustive list, but rather are exemplary in nature for describing the invention.

[0059] They show: Figure 1 is an isometric top view of the quick-change chuck according to the invention; Figure 2 is an exploded view of an isometric front view of the quick-change chuck according to Figure 1 ; Figure 3 a side view of the hole saw arrangement according to the invention; Figure 4 a front view of the hole saw arrangement according to Figure 3 from the front; Figure 5 a longitudinal section of the hole saw arrangement according to Figure 4 in side view along lines AA according to Figure 4; Figure 6 a longitudinal section of the hole saw arrangement according to Figure 4 along line BB according to Figure 4 ; Figure 7 a rear view of the hole saw assembly according to Figure 3 to the drive end; Figure 8 an enlarged side view of the clamping ring; Figure 9 a top view of the clamping ring according to Figure 8 ; Figure 10 an enlarged section of the central area of ​​the clamping ring according to Figure 9 (Detail A); Figure 11 an isometric front view of a clamping jaw; Figure 12 a front view of the clamping jaw according to Figure 11 ; Figure 13 a front view of the clamping jaw according to Figure 11 from the front; Figure 14 a side view of the clamping jaw according to Figure 11 ; Figure 15 a top view of the clamping jaw according to Figure 11 ; Figure 16 is a front view of the quick-change chuck with the hole saw removed.; and Figure 17 is an enlarged plan view of three clamping jaws in the preferred arrangement in the base body.

[0060] Figure 1shows an isometric side view of the hole saw arrangement 1 according to the invention comprising a quick-change chuck 2 with its, to which a hole saw 32 is fastened at the front connection end and in which a center drill 28 is further inserted along the central axis of rotation D at the front or distal side.

[0061] Figure 2 shows an isometric exploded view of the hole saw assembly according to Figure 1 .

[0062] Accordingly, the base body 4 is designed as a substantially rotationally symmetrical, cylindrical rotary part, which extends along a rotational axis D from a rear - proximal - drive end to a front - distal - connection end. At the drive end, the base body is designed for connection to a drive, in particular a drill chuck, for which purpose, in the present embodiment, a hexagon 5 extending along the rotational axis D at the drive end is inserted into the base body 4. This hexagon 5 is preferably detachably connected to the base body 4, but can also be formed integrally with the base body 4.

[0063] At the distal connection end, the base body 4 has three radially extending clamping jaw receptacles 4.1 which are offset from one another by 120 degrees with their central longitudinal axes, which are sized to accommodate three correspondingly designed clamping jaws 14, each of which is radially displaceable in the clamping jaw receptacles 4.1 of the base body 4.

[0064] The clamping jaws 14 each comprise a clamping jaw base 14.1, which in this case is designed similarly to a step, i.e., has a radially outwardly projecting vertical section 4.2, to which a horizontal section 4.3 extending radially inward from this vertical section adjoins at a right angle. The clamping jaw base functions as the insertion section of the clamping jaw 14, i.e., is designed to be inserted in a relatively movable manner into one of the three clamping jaw receptacles of the base body 4, which are offset by 120 degrees from one another. The vertical section does not have a straight front side on the outer edge, but rather an outer cylindrical curvature. On the distal upper side of the horizontal section 14.3, a pin hole 14.4 is provided, into which a guide pin 20 can be inserted.

[0065] On the upper side of the horizontal section 14.3, a hollow cylinder section 14.5 is provided, offset from the axis of rotation D, here formed in one piece, which extends distally upwards and has, on the upper half, a threaded segment section 14.6 with a threaded segment on the outer surface of the hollow cylinder section 14.5. This forms the clamping section of the clamping jaw 14. The proximal hollow cylinder section 14.5 is somewhat wider than the distal threaded segment section, so that a hole saw with smaller central threaded openings with an inner diameter of preferably 9 / 16 inch can be placed on the threaded segment section 14.6 with an adapter ring 36 interposed.

[0066] Larger hole saws with a correspondingly larger central thread opening of usually 5 / 8 inch, on the other hand, are clamped without use of this adapter ring 36 with the proximal hollow cylinder section 14.5 of the clamping jaws 14, which has a correspondingly larger outer diameter than the threaded section 14.6.

[0067] A radially widened collar 14.7 can be formed at the transition between the proximal hollow cylinder section 14.5 and the distal threaded section 14.6.

[0068] A relative movement between the base body 4, which accommodates the clamping jaws 14 in a relatively movable manner and is preferably designed to be as rotationally symmetrical as possible, and the hole saw 32 is partially effected by the spring-loaded clamping jaws 14 and also by the driving pins 38, which, in the installed position, engage in correspondingly designed pin openings 32.4 in the saw base 32.2 of the hole saw 32. These driving pins 38 are inserted into corresponding retaining holes in the cover 8 on both sides of the rotation axis D or are connected to it.

[0069] As can be seen particularly well from the enlarged front view of the keyless chuck in Figure 16 or the clamping jaws outside the keyless chuck in Figure 17As can be seen, three such clamping jaws 14 with the hollow cylinder sections 14.5 and with external thread segment sections 14.6 in the radially external engagement position form the external thread, onto which a hole saw with a corresponding internal thread in the saw base 32.2 of the hole saw 32 (central thread opening) can be placed.

[0070] The clamping ring 4, which together with the guide pins 20 forms the linear gear, is closer to the Figures 3 to 5shown. The clamping ring 4 consists of a circular metal body which forms or extends in a clamping ring main plane E extending transversely to the rotation axis D. In this clamping ring main plane E of the clamping ring 4, three guide curves 6.2 are provided, corresponding to the clamping jaws 14 or the guide pins 20 inserted therein, radially offset outwards from a central through-opening 6.1, each of which extends from a curve front end 6.2.1 to a curve rear end 6.2.2.

[0071] The curvature and the geometric design of the guide curves 6.2 thus determine the adjustment path of the clamping jaws 14 when the clamping ring 4 rotates about the rotation axis D.

[0072] A radially outwardly projecting projection 6.2.3 is formed on the outside of the front end of the curve 6.2.1, which acts as a locking device for the clamping ring 6 in the retracted release position. Only after the locking force created by this locking device has been overcome does the clamping ring automatically move into the engaged position by rotating clockwise due to the spring force.

[0073] Typically, this adjustment range of the clamping jaws 14 is only a few millimeters, preferably 1.4 to 3 mm, which is why the guide curve 6.2 is designed to be almost linear and has only a slight curvature. Specifically, the guide curve 6.2 extends with the front end 6.2.1 of the curve, with its radial outer side, almost adjacent to the center circle 22, whereas the rear end 6.2.2 of the curve is designed in the main plane E of the clamping ring such that the center circle 22 runs almost centrally in the rear end 6.2.2 of the curve. Therefore, the guide curve 6.2 does not run along a circular path around the rotational axis D, but rather runs slightly radially outward in a clockwise direction.

[0074] By means of the compression springs 24 inserted into spring openings 14.7 of the clamping jaws on the inside of each clamping jaw base 14.1, which press against a central area of ​​the base body 4, the guide pin 20 inserted in the horizontal section 14.3 of the clamping jaw 14 is pressed against the outer edge of the guide curve 6.2 and is guided by this outer edge upon rotation of the clamping ring 6. After overcoming the release force generated by the projection 6.3, the clamping jaws 14 are automatically pressed outwards into the engaged position by the spring force of the compression springs 24 upon rotation of the clamping ring 6 clockwise. Conversely, the clamping jaws 14 are pulled radially inwards against the spring force into the release position upon rotation of the clamping ring 6 counterclockwise.

[0075] In particular from Figures 16 and 17It can be seen that the thread segments 14.6 of the clamping jaws 14 at the distal end of the hollow cylinder sections 14.5 each extend over a range of approximately 120 degrees, so that three thread segments together - with an interruption - form an external thread onto which a hole saw 32 can be placed and fixed.

[0076] The clamping ring 6 comprises an outer flange 6.5 which extends distally and proximally, preferably by the same amount, on the outer peripheral edge of the clamping ring main plane E which is defined by the clamping ring and extends transversely to the axis of rotation and in which a clamping ring plate preferably extends, and which is designed to sit on the base body 4 on the distal side and to encompass it and to receive the cover 8 on the distal side.

[0077] The cover 8 is screwed to the front section of the base body 4 between the clamping jaw receptacles 4.1 via the three countersunk head screws 10, in which threaded holes are provided for receiving the countersunk head screws.

[0078] In order to avoid over-tightening of the cover 8 and thus jamming of the clamping ring 6, metal rings acting as spacer bushes are inserted into rotary openings 6.4 on the clamping ring 6, which are formed on an outer circle outside the guide slots 6.2.

[0079] A centering drill 28 can be fixed centrally in the base body 4 by means of a grub screw 26 screwed into a thread at the side.

[0080] In summary, the invention relates to a quick-change chuck for connecting a hole saw to a drive, e.g., a drill. The quick-change chuck, which can be rotated about a rotational axis, has threaded segments arranged around the rotational axis for detachable connection to a hole saw to form an external thread. At least one threaded segment is arranged on an adjustable clamping jaw preloaded by a spring, and the at least one threaded segment can be moved against a spring force from a radially outward engagement position into a release position located further radially inward relative to this engagement position. To simplify the release of the at least one clamping jaw, a clamping ring is provided which can be rotated about the rotational axis and is designed to move the at least one clamping jaw from the engagement position into the release position upon rotation. Preferably, three clamping jaws are provided. List of reference symbols

[0081] DRotation axis EMain plane 1Hole saw arrangement 2Quick-change chuck 4Base body 4.1 4.2Clamping jaw receptacle Threaded hole 5Hexagon 6Clamping ring 6.1Through opening 6.2Guide curve 6.2.1Curve front end 6.2.2Curve rear end 6.3Protrusion 6.4Rotary opening 6.5Outer flange 8Cover 10Countersunk head screw 12Hexagon 14Clamping jaw 14.1Clamping jaw base 14.2Vertical section 14.3Horizontal section 14.4Pin hole 14.5Hollow cylinder section 14.6Threaded segment section 14.7Spring opening 14.8Collar 20Guide pin 22Center circle 24Compression spring 26Set screw 28Center drill 30Spacer bush 32Hole saw 32.1Saw ring 32.2Saw base 32.3Central threaded opening 32.4Bolt opening 36Adapter ring 38Driver bolt

Claims

1. A quick-change chuck for a hole saw (32) that can be rotated about an axis of rotation (D), which extends along the axis of rotation (D) from a rear drive end designed for detachable connection to a drive to a front connection end for detachable connection to the hole saw (32), comprising a base body (4) having at least one clamping jaw receptacle and at least one clamping jaw (14) arranged therein and radially adjustable in relation to the axis of rotation (D), wherein thread segments (14.6) arranged around the axis of rotation are provided at the connecting end to form an external thread, wherein at least one thread segment (14.6) is formed on the clamping jaw (14), wherein a spring (24) is arranged between the clamping jaw (14) and the base body (4), CHARACTERIZED IN that a clamping ring (6) rotatable about the axis of rotation (D) is provided, which is designed, upon rotation, to move the at least one clamping jaw (14) with the threaded segment (14.6) against the spring force from an engagement position located further radially outwards into a release position located further radially inwards in relation to this engagement position, that the clamping ring comprises at least one guide cam (6.2) for forming a guide slot in a clamping ring main plane extending transversely to the axis of rotation, with a cam front end (6.2.1) and a cam rear end (6.2.2), that the front end of the curve (6.2.1) is located radially closer to the axis of rotation (D) than the rear end of the curve (6.2.2) and that a guide pin (20) cooperating with and guided by that one guide cam is provided on the at least one clamping jaw.

2. Quick-change clamping chuck according to one of the preceding claims, CHARACTERIZED IN THAT the clamping ring (6) can be connected to a base body (4) via a preferably plate-shaped cover (8).

3. Quick-change clamping chuck according to claim 2, CHARACTERIZED IN THAT in that the cover (8) is connected to the base body by screws which pass through rotary openings (6.4) in the clamping ring (6) acting as guides.

4. Quick-change clamping chuck according to claim 3, CHARACTERIZED IN THAT the screws are enclosed by spacer bushes (30).

5. Quick-change chuck according to one of the preceding claims, CHARACTERIZED IN THAT it has three clamping jaw mounts (4.1) for movably holding three clamping jaws (14), each with a threaded segment (14.6).

6. Quick-change chuck according to claim 5, CHARACTERIZED IN THAT the clamping ring (6) has a separate guide curve (6.2) for each clamping jaw (14).

7. Quick-change clamping chuck according to one of the preceding claims, CHARACTERIZED IN THAT the clamping ring (6) has a clamping ring main plane (E) extending transversely to the axis of rotation in the installed position and in that clamping ring positioning means are provided between the clamping ring (6) and the base body (4), which realize a coaxial and rotationally movable arrangement of the clamping ring (6).

8. Quick-change clamping chuck according to claim 7, CHARACTERIZED IN THAT the clamping ring positioning means comprise a flange formed radially on the outside of the clamping ring (6), which flange overreaches at least the base body (4) in the installed position.

9. Quick-change chuck according to one of the preceding claims, CHARACTERIZED IN THAT in that the rotating ring comprises a locking device.

10. Quick-change chuck according to claim 9, CHARACTERIZED IN THAT the locking device has a radially outwardly extending projection (6.3).

11. Quick-change chuck according to one of the preceding claims, CHARACTERIZED IN THAT the at least one clamping jaw comprises an insert section designed for relatively movable insertion into a complementarily designed clamping jaw receptacle of the base body (4) and a clamping section adjoining the latter, which is designed for clamping with a central threaded opening in the saw base of the hole saw (32).

12. Quick-change chuck according to claim 11, CHARACTERIZED IN THAT the clamping section comprises a hollow cylinder section (14.5) adjoining to the insert section in the installed position displaced in parallel to the axis of rotation (D) from the insert section and changing into a distally extending threaded section with an outside external thread segment (14.6).