GB2592001A

GB2592001A - End stop

Info

Publication number: GB2592001A
Application number: GB2001619.2A
Authority: GB
Inventors: Jason Wilding Matthew
Original assignee: Wilding Tech Ltd
Current assignee: Wilding Tech Ltd
Priority date: 2020-02-06
Filing date: 2020-02-06
Publication date: 2021-08-18
Anticipated expiration: 2040-02-06
Also published as: GB202001619D0; GB2592001B

Abstract

An end stop device 130 for a chuck assembly 128 comprising a body 132 defining a bore 134 configured to receive a work piece, and a piston 136 within the bore defining an end stop 138 axially movable between a first position and a second position; the end stop device having attachment means 140 for fastening the body to a chuck 110 and aligning the bore with a chuck opening 116. The attachment means may fasten around the chuck opening and comprise at least one radially extending abutment surface. The piston may have an elongate rod 150 coupled thereto configured to move the piston with a securing means that selectively engages the rod to limit movement of the piston. The securing means may comprise a collet 152 receiving the rod and a rotatable nut 158 for axially moving the collet. An indicator scale 170 may show the end stop position.

Description

End Stop

FIELD OF THE INVENTION

The present invention relates to an end stop for a chuck assembly and to a chuck assembly including an end stop.

BACKGROUND OF THE INVENTION

A chuck is a type of radial clamp used to hold a work piece (i.e. an object to be machined) or a tool (e.g. drill bit). An example machine which uses a chuck is a lathe having a rotatable chuck to clamp a work piece. After clamping, the chuck and work piece are rotated so that machine operations (e.g. cutting, sanding, facing) can be carried out via applying tools to the work piece. This process creates an object with symmetry around the axis of rotation of the chuck.

A common type of chuck provided on a machine (e.g. a lathe) has a body with a bore for receiving a work piece, and a plurality of jaws coupled to the body. The jaws can be moved radially inwards or outwards with respect to the bore of the body, in order to engage or disengage a work piece (e.g. moving radially inwards to engage a work piece to be machined, or moving radially outwards to disengage a machined object). The jaws are often actuated hydraulically (e.g. including a hydraulic cylinder/piston), or via another means (e.g. pneumatic, electric or mechanical). For example, Figure 1 shows a chuck of this type.

In some cases, it may be desirable to machine an object held in a chuck to a high degree of precision (e.g. if an automated/CNC lathe is used to machine multiple identical objects one after another). To achieve this, an end stop may be fixed in or adjacent to the bore of the chuck. Such an end stop typically defines a fixed abutment surface which a work piece can be pushed against prior to clamping by the jaws of the chuck. This ensures that each work piece inserted into the chuck is held in the exact same position with respect to the chuck and any tools which are applied to the work piece.

The present invention seeks to overcome, or at least mitigate, one or more problems of

the prior art.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, an end stop device for a chuck is provided, the end stop device comprising: a body defining a bore configured to receive a portion of a work piece; an axial end stop positioned within the bore; and an attachment means for fastening the body to a chuck and for aligning the bore with an opening of a chuck.

By providing an attachment means for aligning the bore of the end stop device with an opening of a chuck, a work piece positioned through the opening of the chuck can be received in the bore. The axial end stop positioned within the bore defines the axially furthest extent of an end of the work piece, which prevents the work piece from moving further in this axial direction during a machining operation and ensures that different workpieces can be located to the exact same machine position.

By providing a means for fastening the body to a chuck, the end stop device can be provided as a separate device for retrofitting to a chuck, rather than as an integral part of a chuck.

Furthermore, when fastened to a chuck, the body will rotate with the chuck. This means that as the chuck rotates, a work piece attached to the chuck and positioned within the bore of the end stop device does not rotate with respect to the bore, which could cause damage to the end stop device and/or work piece.

In exemplary embodiments, the end stop device further comprises a piston positioned within the bore, wherein the piston is configured to define an axial end stop for a work piece, and wherein the piston is axially movable within the bore in order to alter the position of the axial end stop.

Having a piston which is axially movable within the bore to alter the position of the axial end stop provides a simple means of providing an adjustable axial end stop. Furthermore, since a piston can move continuously within a bore, there are an infinite number of potential axial end stop positions. This is more flexible than alternative axial end stop means (e.g. an arrangement where spacers are added to provide a number of discrete axial end stop positions).

In exemplary embodiments, the attachment means is arranged circumferentially with respect to a longitudinal axis of the body.

Arranging the attachment means circumferentially allows the body to be attached to a chuck around its circumference (and therefore supported around its circumference), which reduces the chance of the body tilting or rotating such that the bore and the opening of the chuck become misaligned.

In exemplary embodiments, the attachment means is configured for fastening around an opening of a chuck so that a longitudinal axis of the bore is coaxial with a longitudinal axis of the opening.

Arranging the longitudinal axis of the bore and the longitudinal axis of the opening coaxially ensures that a work piece inserted into the opening can also be inserted into the bore.

In exemplary embodiments, the attachment means comprises one or more abutment surfaces for contacting one or more corresponding surfaces of a chuck, and wherein the one or more abutment surfaces extend radially with respect to a longitudinal axis of the body.

The interaction between the one or more abutment surfaces and the one or more corresponding surfaces of a chuck helps to resist any forces which would tend to tilt or rotate the body of the end stop device (i.e. this interaction helps to resist any forces which would cause the bore and the opening to become misaligned).

Furthermore, the one or more abutment surfaces also provide a means of axially limiting movement of the end stop device with respect to a chuck, at least in one direction, since the one or more abutment surfaces cannot move past the one or more corresponding surfaces of the chuck.

In exemplary embodiments, the one or more abutment surfaces each define a substantially flat surface.

Chucks often have a substantially flat front and or rear face (e.g. typically there is a flat face behind the hydraulic jaws of a hydraulic chuck). Therefore, having abutment surfaces with a substantially flat surface allows the attachment means to be fastened to such a chuck.

20 25 30 In exemplary embodiments, the one or more abutment surfaces are provided at a first axial end of the body.

By providing the one or more abutment surfaces at a first axial end of the body, the abutment surfaces can be fastened to a front face of a chuck (e.g. on the face behind the hydraulic jaws on a hydraulic chuck) with the body of the end stop device being located within a bore of the chuck so that an axial end of the bore is flush with the front face of the chuck. This allows the axial end stop to be located at the axial position of the front face (e.g. to define a short axial end stop position for a short work piece) or any position within the bore further back from the front face (e.g. to define a longer axial end stop position for longer work pieces).

Alternatively, by providing the one or more abutment surfaces at a first axial end of the body, the abutment surfaces can be fastened to a rear face of a chuck with the body of the end stop device being located behind, rather than within, a bore of the chuck. This ensures that the body does not extend into the opening, which prevents any movement in the bore of the chuck (e.g. compression of the bore in the case of a collet chuck) from damaging the end stop device. This also prevents the end stop device from stopping the bore of the chuck from being sufficiently compressed in order to hold a work piece positioned therein.

In exemplary embodiments, the one or more abutment surfaces are provided at a position between a first axial end of the body and a second axial end of the body, so that a first axial end of the bore extends axially beyond the one or more abutment surfaces.

Providing the one or more abutment surfaces at a position between a first axial end of the body and a second axial end of the body, allows the abutment surfaces to be fastened to a rear face of a chuck (i.e. out of the way of any jaws or the like at a front face of the chuck) whilst the first axial end of the bore extends axially into a bore of the chuck. In this way, the axial end stop can be positioned in front of the rear face of the chuck, which may be desirable for shorter work pieces.

In exemplary embodiments, the one or more abutment surfaces comprise one or more holes for receiving a screw, bolt or the like to fasten the one or more abutment surfaces to one or more corresponding surfaces of a chuck.

Screws and bolts provide a simple means of fastening two abutting surfaces together. Furthermore, screws and bolts are releasable which would allow the end stop device to be removed from a chuck (e.g. for use on a different chuck, or for compact storage).

In exemplary embodiments, the end stop device further comprises a drive means configured to move the piston.

Having a drive means configured to move the piston provides a means for altering the position of the axial end stop within the bore.

In exemplary embodiments, the drive means comprises an elongate member in the form of a rod coupled to the piston.

Having an elongate member coupled to the piston ensures that any movement of the elongate member results in a corresponding movement of the piston. Therefore the position of the axial end stop can be easily moved via pushing or pulling the elongate member (either manually or via an actuator coupled to an end of the elongate member distal the piston).

In exemplary embodiments, the end stop device further comprises a securing means configured to selectively engage the drive means so that movement of the piston within the bore is inhibited.

Having a securing means configured to selectively engage the drive means so that movement of the piston within the bore is inhibited allows position of the axial end stop to be fixed at a desired position. In other words, this ensures that the axial end stop does not move during a machining operation of a chuck to which the end stop device is attached.

This prevents a work piece in abutment with the axial end stop from moving axially during a machining operation, which improves safety and accuracy of the machining operation (e.g. by preventing the work piece from moving in relation to a machine position).

In exemplary embodiments, the securing means comprises an annular securing member configured to surround the drive means.

By having an annular securing means surrounding the drive means, the securing means is able to engage the drive means so that movement of the piston within the bore is inhibited regardless of the relative rotational orientation of the drive means and the securing means. In other words, there is no need to align the securing means with a feature of the drive means.

In exemplary embodiments, the annular securing member is a collet.

A collet is known as an effective means for securing the position of a cylindrical object, since it provides a compressive force around the entire circumference of the cylindrical object (e.g. elongate member). This reduces the chance of movement of the elongate member over alternative securing means (e.g. tightening bolts which engage the elongate member at points rather than over the entire circumference of the elongate member).

In exemplary embodiments, the securing means comprises an actuation mechanism configured to move the annular securing member in an axial direction in order to engage the drive means.

Having an actuation mechanism configured to move the annular securing member in an axial direction in order to engage the drive means, provides a means for transitioning the annular securing member between an engaged and a disengaged state.

In exemplary embodiments, the actuation mechanism comprises a nut configured to move the annular securing member in an axial direction; wherein the nut is rotatable in a first direction to move the annular securing member in a first axial direction, in order to inhibit movement of the drive means relative to the annular securing member; and wherein the nut is rotatable in a second direction opposite the first direction to permit the annular securing member to move in a second axial direction opposite the first axial direction, in order to permit movement of the drive means relative to the annular securing member.

Having a nut configured to move the annular securing member provides a simple means of engaging or releasing the securing means (i.e. via tightening the nut via rotation in the first direction, or releasing the nut via rotation in the second direction) In exemplary embodiments, the securing means comprises a receiving formation configured to receive the annular securing member and to exert a compressive force on the annular securing member as the annular securing member is moved axially into the receiving formation.

Such a receiving formation provides a means of converting a force applied by the actuation mechanism in the axial direction to a force applied to the annular securing member in a radially inwards direction (i.e. a compressive force), so that the drive member (e.g. elongate member) is engaged by the annular securing member.

In exemplary embodiments, the annular securing member is a collet and the receiving formation comprises an angled surface configured to provide a compressive force to the collet.

Such an angled surface arrangement is known as an effective means for providing a compressive force to a collet (e.g. via interaction of the angled surface with a corresponding surface of the collet as it moves axially into the receiving formation).

In exemplary embodiments, the actuation means comprises a nut configured to be arranged on the receiving formation so that the annular securing member is positioned between the nut and the receiving formation.

By positioning the annular securing member between the nut and the receiving formation, the nut and the receiving formation provide a housing for the annular securing member, which ensures the annular securing member is suitable positioned with respect to the drive means.

In exemplary embodiments, the nut is rotatable in the first direction to move the annular securing member axially into the receiving formation.

The nut being rotatable in the first direction in order to move the annular securing member axially into the receiving formation (i.e. rotatable in the first direction to cause axial movement of the nut and annular securing member towards the receiving formation), provides a simple mechanism for actuating the securing means (e.g. using a spanner or wrench to rotate the nut).

In exemplary embodiments, the receiving formation comprises a threaded outer radial surface and the nut comprises a threaded inner radial surface configured for engagement with the threaded outer radial surface of the receiving formation.

Having a threaded arrangement between the receiving formation and the nut provides a means for axially altering the position of the nut with respect to the receiving formation (and therefore the position of the annular securing member with respect to the angled surface) via rotation of the nut. Furthermore, such a threaded arrangement axially fixes the relative positions of the nut and the receiving formation, unless the nut is rotated.

In exemplary embodiments, the drive means is coupled to the piston via a releasable engagement.

Having a releasable engagement between the piston and the drive means allows these components to be assembled/disassembled, which provides numerous advantages. For example, if one of these components becomes damaged, it can be replaced without having to replace the other. Disassembling these parts may also be desirable for cleaning/maintenance, and more compact storage for transport or shipping etc. In exemplary embodiments, the releasable engagement between the drive means and the piston comprises a threaded arrangement.

In exemplary embodiments, the piston comprises a threaded hole and the drive means comprises a threaded first end configured for engagement with the threaded hole of the piston.

Such a threaded arrangement is a reliable and simple means of coupling two components.

In exemplary embodiments, the drive means is manually actuatable.

Having a manually actuatable drive means is cheaper than other options (e.g. an automatic drive means which uses sensors, actuators and a control system). Furthermore, there is no requirement for the end stop device to be connected to a power supply to adjust the drive means, which offers a simple arrangement which is more easily retrofitted to a chuck.

In exemplary embodiments, the end stop device further comprises a handle coupled to the elongate member at an end of said elongate member distal the piston.

Having a handle coupled to the elongate member provides a simple means for manually adjusting the position of the piston within the bore.

In exemplary embodiments, the elongate member is coupled to the handle via a releasable engagement.

Having a releasable engagement between the handle and the elongate member allows these components to be assembled/disassembled, which provides numerous advantages. For example, if one of these components becomes damaged, it can be replaced without having to replace the other. Disassembling these parts may also be desirable for cleaning/maintenance, and more compact storage for transport or shipping etc. In exemplary embodiments, the releasable engagement between the elongate member and the handle comprises a threaded arrangement; optionally, wherein the handle comprises a threaded hole and the elongate member comprises a threaded second end configured for engagement with the threaded hole of the handle.

In exemplary embodiments, the end stop device further comprises an actuator configured to accurately set the position of piston within the bore.

By having an actuator (e.g. an electric, hydraulic, electrohydraulic, magnetic actuator or the like) configured to set the position of the piston within the bore, the axial end stop may be more accurately positioned than with a manual drive means.

In exemplary embodiments, the actuator is coupled to an end of the elongate member distal the piston.

In exemplary embodiments, the end stop device further comprises an indicator configured to show the position of the axial end stop within the bore.

Having an indicator configured to show the position of the axial end stop within the bore provides a means of determining whether the axial end stop is at a desired position. This provides feedback to the operator allowing them to move the piston until the axial end stop is at the desired position.

In exemplary embodiments, the indicator comprises a scale on the elongate member.

The extent to which the elongate member protrudes from the body of the end stop device is indicative of the position of the axial end stop within the bore. Therefore, providing a scale on the elongate member provides a visual means of determining the position of the axial end stop.

In exemplary embodiments, the indicator is provided on the body.

In exemplary embodiments, the indicator is in the form of a window through the body and a scale located on or adjacent the window.

By having a window through the body, it is possible to visually see the position of the piston within the bore. Furthermore, by providing a scale on or adjacent the window, it is possible to determine the position of the axial end stop by visually noting the position of the end of the piston on the scale.

In exemplary embodiments, the indicator comprises a sensor configured to determine the position of the axial end stop and a visual display configured to output the position of the axial end stop determined by the sensor.

A sensor may provide a more accurate indication of the position of the axial end stop than a manual visual indicator.

According to a second aspect of the invention, a chuck assembly is provided, the chuck assembly comprising: an opening configured to receive an end of a work piece therethrough; a bore arranged coaxially with the opening in order to receive a portion of a work piece therein; and a piston positioned within the bore, wherein the piston is configured to define an axial end stop for a work piece, and wherein the piston is axially movable within the bore in order to alter the position of the axial end stop.

In exemplary embodiments, the chuck assembly further comprises a drive means configured to move the piston.

In exemplary embodiments, the drive means comprises an elongate member coupled to the piston.

In exemplary embodiments, the chuck assembly further comprises a securing means configured to selectively engage the drive means so that movement of the piston within the bore is inhibited.

In exemplary embodiments, the annular securing member is a collet.

In exemplary embodiments, the actuation mechanism comprises a nut configured to move the annular securing member in an axial direction; wherein the nut is rotatable in a first direction to move the annular securing member in a first axial direction, in order to inhibit movement of the drive means relative to the annular securing member; and wherein the nut is rotatable in a second direction opposite the first direction to permit the annular securing member to move in a second axial direction opposite the first axial direction, in order to permit movement of the drive means relative to the annular securing 20 member.

In exemplary embodiments, the drive means is manually actuatable.

In exemplary embodiments, the chuck assembly further comprises a handle coupled to the elongate member at an end of said elongate member distal the piston.

In exemplary embodiments, the chuck assembly further comprises an actuator configured to accurately set the position of piston within the bore.

In exemplary embodiments, the chuck assembly further comprises an indicator configured to show the position of the axial end stop within the bore.

The extent to which the elongate member protrudes from an end stop body of the chuck assembly is indicative of the position of the axial end stop within the bore. Therefore, providing a scale on the elongate member provides a visual means of determining the position of the axial end stop.

In exemplary embodiments, the indicator is provided on an end stop body of the chuck assembly.

In exemplary embodiments, the indicator is in the form of a window through the end stop body and a scale located on or adjacent the window.

By having a window through the end stop body, it is possible to visually see the position of the piston within the bore. Furthermore, by providing a scale on or adjacent the window, it is possible to determine the position of the axial end stop by visually noting the position of the end of the piston on the scale.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an isometric view of a hydraulic chuck; Figure 2 is a cross-sectional view of a chuck assembly including an end stop device according to an embodiment; Figure 3 is a cross-sectional view of a chuck assembly including an end stop device according to an alternative embodiment; and Figure 4 is a cross-sectional view of a chuck assembly including an end stop device according to an alternative embodiment.

DETAILED DESCRIPTION

Referring to Figure 1, a chuck of the prior art is indicated generally at 10. The chuck includes a chuck body 12 and a chuck bore 14 defining a longitudinal axis through the chuck body 12. The chuck bore 14 has a first opening 16 at a first end 18 of the chuck body 12. The first opening 16 is configured to receive an end of a work piece therethrough.

The chuck bore 14 also has a second opening 20 at a second end 22 of the chuck body 12.

The chuck 10 has a plurality of jaws 24 for clamping a work piece therebetween. In the chuck 10 illustrated in Figure 1, the chuck body 12 has a corresponding plurality of channels 26 for receiving a portion of the jaws 24, in order to couple the jaws 24 to the chuck body 12. The jaws 24 and channels 26 include complementary formations (e.g. grooves in the jaws 24 for engaging rails in the channels 26), so that the jaws 24 may move relative to the chuck body 12 in a radial direction but not in a longitudinal direction (with respect to the chuck bore 14). In alternative chucks, the jaws 24 may be coupled to the chuck body 12 via a different means (e.g. attached to rails protruding from the first end 18 of the chuck body 12).

Referring now to Figures 2 to 4, a chuck assembly including an end stop device according to an embodiment is indicated at 128. The chuck assembly 128 includes a chuck 110 similar to the chuck 10 of Figure 1. Corresponding components between the chuck 10 and chuck 110 are labelled with the prefix "1", and only additions/differences are discussed.

The chuck assembly 128 has an end stop device 130 including an end stop body 132 defining an end stop bore 134 configured to receive a portion of a work piece. The end stop body 132 has a smaller diameter than the chuck bore 114, so that the end stop body 132 can be located within the chuck bore 114. The end stop device 130 also includes a piston 136 positioned within the end stop bore 134. The piston 136 is configured to define an axial end stop 138 for a work piece. The piston 136 is axially movable within the end stop bore 134, in order to alter the position of the axial end stop 138. The axial end stop 138 positioned within the end stop bore 134 defines the axially furthest extent of an end of the work piece, which ensures that different work pieces can be located to the exact same machine position. Having a piston 136 which is axially movable within the end stop bore 134 to alter the position of the axial end stop 138 provides a simple means of providing an adjustable axial end stop 138. Furthermore, since the piston 136 can move continuously within the end stop bore 134, there are an infinite number of potential axial end stop 138 positions. This is more flexible than alternative axial end stop means (e.g. an arrangement where spacers are added to provide a number of discrete axial end stop positions).

In the illustrated embodiments, the end stop device 130 also includes an attachment means 140 for fastening the end stop body 132 to the chuck 110 and for aligning the end stop bore 134 with the first opening 116 of the chuck 110, as will be described in more detail below. By providing an attachment means 140 for aligning the end stop bore 134 with the first opening 116 of the chuck 110, a work piece positioned in the first opening 116 can be received in the end stop bore 134. By providing a means for fastening the end stop body 132 to the chuck 110, the end stop device 130 can be provided as a separate device for retrofitting to the chuck 110, rather than as an integral part of the chuck 110. Furthermore, when fastened to the chuck 110, the end stop body 132 will rotate with the chuck 110. This means that as the chuck 110 rotates, a work piece attached to the chuck 110 and positioned within the end stop bore 134 does not rotate with respect to the end stop bore 134, which prevents damage to the end stop device 130 and/or work piece.

In alternative embodiments, the end stop device 130 may be integral to the chuck 110 (e.g. the end stop body 132 may be integrally formed with the chuck body 112).

The attachment means 140 is arranged circumferentially with respect to a longitudinal axis of the end stop body 132. Arranging the attachment means 140 circumferentially allows the end stop body 132 to be attached to the chuck 110 around its circumference (and the end stop body 132 is therefore supported around its circumference). This reduces the chance of the end stop body 132 tilting or rotating such that the end stop bore 132 and the first opening 116 of the chuck 110 become misaligned.

The attachment means 140 is configured for fastening around the first opening 116 of the chuck 110 so that a longitudinal axis of the end stop bore 134 is coaxial with a longitudinal axis of the chuck bore 114. Arranging the longitudinal axes of the end stop bore 134 and chuck bore 114 coaxially ensures that a work piece inserted through the first opening 116 can also be inserted into the end stop bore 134.

The attachment means 140 includes an abutment surface 142 for contacting a corresponding surface 144 of the chuck 110. The abutment surface 142 extends radially with respect to a longitudinal axis of the end stop body 132. The abutment surface 142 also defines a substantially flat surface. The abutment surface 142 may be in the form of a radial flange surrounding the circumference of the end stop body 132. In alternative embodiments, a plurality of abutment surfaces 142 may be provided (e.g. a plurality of radial flanges, each radial flange surrounding only a portion of the circumference of the end stop body 132).

In the embodiment illustrated in Figure 2, the corresponding surface 144 is in the form of a recessed shoulder of the chuck body 112, the shoulder 144 surrounding the first opening 116. In alternative embodiments (e.g. embodiments with a plurality of abutment surfaces 142), a corresponding plurality of recessed shoulders 144 may be provided. In alternative embodiments, the corresponding surface(s) 144 may just be the portion of the first end 118 of the chuck body 112 surrounding the first opening 116 (i.e. the shoulder may be omitted). In such cases, the jaws 24 would have to be spaced apart from the first end 118 of the chuck body 112, in order to accommodation the abutment surface 142.

In the embodiments illustrated in Figures 3 and 4, the corresponding surface(s) 144 are the portion of the second end 122 of the chuck body 112 surrounding the second opening 120. In alternative embodiments, the corresponding surface(s) 144 may be one or more recessed shoulders surrounding the second opening 120.

The interaction between the abutment surface(s) 142 of the end stop device 130 and the corresponding surface(s) 144 of the chuck 110 helps to resist any forces which would tend to tilt or rotate the end stop body 132 (i.e. this interaction helps to resist any forces which would cause the end stop bore 134 and the first opening 116 to become misaligned. Furthermore, the abutment surface(s) also provide a means of axially limiting movement of the end stop device 130 with respect to the chuck 110, at least in one direction, since the abutment surface(s) 142 cannot move past the corresponding surface(s) 144 of the chuck 110.

In the embodiment of Figure 2, the abutment surface(s) 142 are provided at a first axial end 146 of the end stop body 132. Since the abutment surface(s) 142 are configured for attaching to corresponding surface(s) 144 at or proximal the first end 118 of the chuck body 112 (as described above), providing the abutment surface(s) 142 at the first axial end 146 ensures that an axial end of the end stop bore 134 is flush with the first opening 116 of the chuck 110. This allows the axial end stop 138 to be located at the axial position of the first end 118 of the chuck body 112 (e.g. to define a short axial end stop 138 position for a short work piece) or any position within the end stop bore 134 further back from first end 118 of the chuck body 112 (e.g. to define a longer axial end stop 138 position for longer work pieces).

In the embodiment of Figure 3, the abutment surface(s) 144 are also provided at the first axial end 146 of the end stop body 132, but the abutment surface(s) 142 are configured to be fastened to the second end 122 of the chuck body 112. In other words, the end stop body 132 is located behind, rather than within, the chuck bore 114. This ensures that the end stop body 132 does not extend into the chuck bore 114, which prevents any movement in the chuck bore 114 (e.g. compression of the bore 114 in the case of a collet chuck) from damaging the end stop device 130. This also prevents the end stop device 130 from stopping the chuck bore 114 of a collet chuck from being sufficiently compressed in order to hold a work piece positioned therein.

In the embodiment of Figure 4, the one or more abutment surface(s) 142 are provided at a position between the first axial end 146 of the end stop body 132 and a second axial end 147 of the end stop body 132, so that a first axial end 146 of the end stop body 132 extends axially beyond the abutment surface(s) 142. Providing the abutment surface(s) 142 at a position between a first and second axial ends 146, 147 of the end stop body 132 allows the abutment surface(s) to be fastened to the second end 122 of the chuck body 112 (i.e. out of the way of the jaws 24 at the first end 118 of the chuck body 112) whilst the first axial end 146 extends axially into the chuck bore 114. In this way, the axial end stop 138 can be positioned in front of the second end 122 of the chuck body 112, which may be desirable for shorter work pieces.

In the embodiments illustrated in Figures 2 to 4, the abutment surface(s) 142 include holes 148 for receiving a screw, bolt or the like to fasten the abutment surface(s) 142 to the corresponding surface(s) 144 of the chuck 110. Screws and bolts provide a simple means of fastening two abutting surfaces together. Furthermore, screws and bolts are releasable which would allow the end stop device 130 to be removed from the chuck 110 (e.g. for use on a different chuck, for compact storage, or for cleaning/maintenance purposes).

As will be described in detail below, the end stop device 130 includes a drive means configured to move the piston 136. Having a drive means configured to move the piston 136 provides a means for altering the position of the axial end stop 138 within the end stop bore 134.

The drive means includes an elongate member in the form of a rod 150 coupled to the piston 136. Having a rod 150 coupled to the piston 136 ensures that any movement of the rod 150 results in a corresponding movement of the piston 136. Therefore, the position of the axial end stop 138 can be easily moved via pushing or pulling the rod 150 (either manually or via an actuator coupled to an end of the rod 150 distal the piston).

As will be described in detail below, the end stop device 130 also includes a securing means configured to selectively engage the drive means so that movement of the piston 136 within the end stop bore 134 is inhibited. Having a securing means configured to selectively engage the drive means so that movement of the piston 136 within the end stop bore 134 is inhibited allows position of the axial end stop 138 to be fixed at a desired position. In other words, this ensures that the axial end stop 138 does not move during a machining operation of the chuck assembly 128.

The securing means includes an annular securing member 152 configured to surround the drive means. By having an annular securing means surrounding the drive means, the securing means is able to engage the drive means so that movement of the piston 136 within the end stop bore 134 is inhibited regardless of the relative rotational orientation of the drive means and the securing means. In other words, there is no need to align the securing means with a feature of the drive means. In alternative embodiments, a non-annular securing means may be provided. For example, one or more bolts which engage the rod 150 at one or more points around its circumference, rather than over the entire circumference.

In the embodiments illustrated in Figures 2 to 4, the annular securing member is a collet 152 which surrounds the rod 150. A collet is known as an effective means for securing the position of a cylindrical object, since it provides a compressive force around the entire circumference of the cylindrical object (e.g. the rod 150).

As will be described in detail below, the securing means includes an actuation mechanism configured to move the annular securing member (collet 152) in an axial direction in order to engage the drive means (rod 150). Having an actuation mechanism configured to move the collet 152 in an axial direction in order to engage the rod 150, provides a means for transitioning the collet 152 between an engaged and a disengaged state.

The securing means includes a collet receiving formation 154 configured to receive the collet 152 and to exert a compressive force on the collet 152 as the collet 152 is moved axially into the collet receiving formation 154 in direction Dl. Such a collet receiving formation 154 provides a means of converting a force applied by the actuation mechanism in a first axial direction D1 to a force applied to the collet 152 in a radially inwards direction (i.e. a compressive force), so that the drive member (e.g. rod 150) is engaged by the collet 152.

The collet receiving formation 154 includes an angled surface 156 configured to provide a compressive force to the collet 152. Such an angled surface arrangement is known as an effective means for providing a compressive force to a collet 152 (e.g. via interaction of the angled surface 156 with a corresponding surface of the collet 152 as it moves axially into the receiving formation 154 in direction D1).

In the embodiments illustrated in Figures 2 to 4, the actuation mechanism includes a nut 158 configured to move the annular securing member (collet 152) in an axial direction. The nut 158 is rotatable in a first direction to move the collet 152 in the first axial direction D1, in order to inhibit movement of the drive means (rod 150) relative to the collet 152. The nut 158 is also rotatable in a second direction opposite the first direction to permit the collet 152 to move in a second axial direction D2 opposite the first axial direction D1, in order to permit movement of the rod 150 relative to the collet 152. Having a nut 158 configured to move the collet 152 provides a simple means of engaging or releasing the securing means (i.e. via tightening the nut 158 via rotation in the first direction, or releasing the nut 158 via rotation in the second direction).

The nut 158 is configured to be arranged on the collet receiving formation 154 so that the annular securing member (collet 152) is positioned between the nut 158 and the receiving formation 154. In this way, the nut 158 and the receiving formation 154 provide a housing for the collet 152, which ensures the collet 152 is suitably positioned with respect to the drive means (rod 150). Rotation of the nut 158 in the first direction moves the annular securing member (collet 152) axially into the collet receiving formation 154 in direction Dl. This provides a simple mechanism for actuating the securing means (e.g. using a spanner or wrench to rotate the nut).

The collet receiving formation 154 has a threaded outer radial surface 160 and the nut 158 has a threaded inner radial surface 162 configured for engagement with the threaded outer radial surface 160 of the collet receiving formation 154. Having a threaded arrangement between the receiving formation 154 and the nut 158 provides a means for axially altering the position of the nut 158 with respect to the receiving formation 154 (and therefore the position of the collet 152 with respect to the angled surface 156) via rotation of the nut 158. Furthermore, such a threaded arrangement axially fixes the relative positions of the nut 158 and the receiving formation 154, unless the nut 158 is rotated.

In the embodiments illustrated in Figures 2 to 4, the drive means (rod 150) is manually actuatable. Having a manually actuatable drive means is cheaper than other options (e.g. an automatic drive means which uses sensors, actuators and a control system).

Furthermore, there is no requirement for the end stop device 130 to be connected to a power supply to adjust the drive means, which offers a simple arrangement which is more easily retrofitted to a chuck 110. In more detail, the end stop device 130 includes a handle 166 coupled to the rod 150 at an end of said rod 150 distal the piston 136. Having a handle 166 coupled to the rod 150 provides a simple means for manually adjusting the position of the piston 136 within the end stop bore 134.

In the embodiments illustrated in Figures 2 to 4, the rod 150 is coupled to the piston 136 via a first releasable engagement 164. The rod 150 is also coupled to the handle 166 via a second releasable engagement 168. Having a releasable engagement between the rod 150 and the piston 136, and the rod 150 and the handle 166, allows these components to be disassembled, which provides numerous advantages. For example, if one of these components becomes damaged, it can be replaced without having to replace the other.

Disassembling these parts may also be desirable for cleaning/maintenance, and more compact storage for transport or shipping etc. In alternative embodiments, the rod 150 and piston 136 and/or handle 166 may be permanently fixed (e.g. welded together) or integrally formed.

The first and second releasable engagements 164, 168 include a threaded arrangement.

The piston 136 has a threaded hole and the rod 150 has a threaded first end configured for engagement with the threaded hole of the piston 136. Similarly, the handle 166 has a threaded hole and the rod 150 has a threaded second end configured for engagement with the threaded hole of the handle 166. Such a threaded arrangement is a reliable and simple means of coupling two components.

In alternative embodiments, the end stop device 130 may include an actuator configured to accurately set the position of piston 136 within the end stop bore 134. By having an actuator (e.g. an electric, hydraulic, electrohydraulic, magnetic actuator or the like) configured to set the position of the piston 136 within the end stop bore 134, the axial end stop 138 may be more accurately positioned than with a manual drive means. Such an actuator may be coupled to an end of the rod 150 distal the piston 136 (e.g. instead of the handle 166).

The end stop device 130 also includes an indicator configured to show the position of the axial end stop 138 within the end stop bore 134. Having an indicator configured to show the position of the axial end stop 138 provides a means of determining whether the axial end stop 138 is at a desired position. This provides feedback to the operator allowing them to move the piston 136 until the axial end stop 138 is at the desired position.

In the embodiments illustrated in Figures 2 to 4, the indicator includes a scale 170 on the rod 150. The extent to which the rod 150 protrudes from the end stop body 132 is indicative of the position of the axial end stop 138 within the end stop bore 134. Therefore, providing a scale 170 on the rod provides a visual means of determining the position of the axial end stop 138.

In alternative embodiments, the indicator is provided on the end stop body 132 in the form of a window through the end stop body 132 and a scale 170 located on the window.

In alternative embodiments, the scale 170 may be located on the end stop body 132 adjacent a window. By having a window through the end stop body 132, it is possible to visually see the position of the piston 136 within the end stop bore 134. Furthermore, by providing a scale 170 on or adjacent the window, it is possible to determine the position of the axial end stop 138 by visually noting the position of the end of the piston 136 on the scale 170. Such indicators are suitable for end stop devices configured to be attached to the second end 122 of a chuck body 112 so that the end stop body 132 does not extend into the chuck bore 114 (e.g. as in Figure 4).

In alternative embodiments, the indicator includes a sensor (not shown) configured to determine the position of the axial end stop 138 and a visual display (not shown) configured to output the position of the axial end stop 138 determined by the sensor. A sensor may provide a more accurate indication of the position of the axial end stop 138 than a manual visual indicator.

Although the invention has been described in relation to one or more embodiments, it will be appreciated that various changes or modifications can be made without departing from the scope of the invention as defined in the appended claims. For example: an alternative type of attachment means 140 may be provided; the chuck assembly 128 may include a different type of chuck (e.g. a collet chuck); an alternative adjustable axial end stop member 136 may be used instead of a piston (e.g. the end stop body 132 may include threads on its inner radial surface, and an axial end stop member 136 having a threaded outer radial surface may be engaged with the threads, so that the position of the axial end stop 138 can be altered via rotation of the end stop member 136 with respect to the end stop body 132); an alternative drive means may be provided (e.g. an automated drive means); an alternative securing means may be provided (e.g. one or more set screws); and an alternative indicator to indicate the position of the axial end stop 138 may be provided.

Claims

CLAIMS1. An end stop device for a chuck comprising: a body defining a bore configured to receive a portion of a work piece; a piston positioned within the bore, wherein the piston is configured to define an axial end stop for a work piece, and wherein the piston is axially movable within the bore in order to alter the position of the axial end stop; and an attachment means for fastening the body to a chuck and for aligning the bore with an opening of a chuck.
2. An end stop device according to claim 1, wherein the attachment means is arranged circumferentially with respect to a longitudinal axis of the body, and wherein the attachment means is configured for fastening around an opening of a chuck so that a longitudinal axis of the bore is coaxial with a longitudinal axis of the opening.
3. An end stop device according to claim 1 or 2, wherein the attachment means comprises one or more abutment surfaces for contacting one or more corresponding surfaces of a chuck, and wherein the one or more abutment surfaces extend radially with respect to a longitudinal axis of the body.
4. An end stop device according to claim 3, wherein the one or more abutment surfaces are provided at a first axial end of the body.
5. An end stop device according to claim 3, wherein the one or more abutment surfaces are provided at a position between a first axial end of the body and a second axial end of the body, so that a first axial end of the bore extends axially beyond the one or more abutment surfaces.
6. An end stop device according to any preceding claim, further comprising: an elongate member in the form of a rod coupled to the piston, wherein the elongate member is configured to move the piston; and a securing means configured to selectively engage the elongate member so that movement of the piston within the bore is inhibited.
7. An end stop device according to claim 6, wherein the securing means comprises: a collet configured to receive the elongate member; and a nut configured to move the collet in an axial direction; wherein the nut is rotatable in a first direction to move the collet in a first axial direction, in order to inhibit movement of the elongate member relative to the collet; and wherein the nut is rotatable in a second direction opposite the first direction to permit the collet to move in a second axial direction opposite the first axial direction, in order to permit movement of the elongate member relative to the collet.
8. An end stop device according to claim 7, wherein the securing means further comprises a collet receiving formation comprising an angled surface, wherein the nut is configured to be arranged on the collet receiving formation so that the collet is positioned between the nut and the collet receiving formation, and wherein the nut is rotatable in the first direction to move the collet axially into the collet receiving formation so that the angled surface provides a compressive force to the collet.
9. An end stop device according to claim 8, wherein the collet receiving formation comprises a threaded outer radial surface and the nut comprises a threaded inner radial surface configured for engagement with the threaded outer radial surface of the collet receiving formation.
10. An end stop device according to any of claims 6 to 9, wherein the elongate member is coupled to the piston via a releasable engagement.
11. An end stop device according to claim 10, wherein the releasable engagement between the elongate member and the piston comprises a threaded arrangement; optionally, wherein the piston comprises a threaded hole and the elongate member comprises a threaded first end configured for engagement with the threaded hole of the piston.
12. An end stop device according to any of claims 6 to 11, further comprising a handle coupled to the elongate member at an end of said elongate member distal the piston.
13. An end stop device according to claim 12, wherein the elongate member is coupled to the handle via a releasable engagement.
14. An end stop device according to claim 13, wherein the releasable engagement between the elongate member and the handle comprises a threaded arrangement; optionally, wherein the handle comprises a threaded hole and the elongate member comprises a threaded second end configured for engagement with the threaded hole of the handle.
15. An end stop device according to any of claims 1 to 11, further comprising an actuator configured to accurately set the position of piston within the bore.
16. An end stop device according to any preceding claim, further comprising an indicator configured to show the position of the axial end stop within the bore.
17. A chuck assembly comprising: an opening configured to receive an end of a work piece therethrough; a bore arranged coaxially with the opening in order to receive a portion of a work piece therein; a piston positioned within the bore, wherein the piston is configured to define an axial end stop for a work piece, and wherein the piston is axially movable within the bore in order to alter the position of the axial end stop.
18. A chuck assembly according to claim 17, further comprising: an elongate member coupled to the piston, wherein the elongate member is configured to move the piston; and a securing means configured to selectively engage the elongate member so that movement of the piston within the bore is inhibited.
19. A chuck assembly according to claim 18, wherein the securing means comprises: a collet configured to receive the elongate member; and a nut configured to move the collet in an axial direction; wherein the nut is rotatable in a first direction to move the collet in a first axial direction, in order to inhibit movement of the elongate member relative to the collet; and wherein the nut is rotatable in a second direction opposite the first direction to permit the collet to move in a second axial direction opposite the first axial direction, in order to permit movement of the elongate member relative to the collet.
20. A chuck assembly according to claim 19, wherein the securing means further comprises a collet receiving formation comprising an angled surface, wherein the nut is configured to be arranged on the collet receiving formation so that the collet is positioned between the nut and the collet receiving formation, and wherein the nut is rotatable in the first direction to move the collet axially into the collet receiving formation so that the angled surface provides a compressive force to the collet.
21. A chuck assembly according to claim 20, wherein the collet receiving formation comprises a threaded outer radial surface and the nut comprises a threaded inner radial surface configured for engagement with the threaded outer radial surface of the collet receiving formation.
22. A chuck assembly according to any of claims 18 to 21, further comprising a handle coupled to the elongate member at an end of said elongate member distal the piston.
23. A chuck assembly according to any of claims 18 to 21, further comprising an actuator configured to accurately set the position of piston within the bore.
24. A chuck assembly according to any of claims 17 to 23, further comprising an indicator configured to show the position of the axial end stop within the bore.