Bush retention method and device

Abstract

A tubular bearing bushing 3 within a housing 1 of a linear movement system. After inserting the bush 3 into the bore 2 of the housing 1, a compressive force is applied to the area around the opening 4

Description

Field The present disclosure relates to a method and device for use in the deformation of a housing for retaining a bush, in the context of a linear movement system. More specifically, the disclosure relates to a method and a tool for swaging the housing so as to retain the bush within the housing. Background In the area of remote or isolated part manipulation solutions for use in vacuum or other clean environments, such as in manufacturing or laboratories, devices and systems may include linear sliders or mechanisms to facilitate a translation or movement of a part, initiated by a user or operator from outside a clean environment, to a corresponding movement inside the clean environment. Such mechanisms may include linear sliders to facilitate such movement. One example of such a device may be a linear actuator. A bush may be referred to as a linear bearing. Summary In some examples, there is provided a method for retaining a substantially tubular bush within a housing of a linear movement system, the housing comprising a bore into which the tubular bush is insertable. The method may comprise inserting the tubular bush through an opening into the bore, such that an outer surface of the tubular bush faces a substantially cylindrical inner wall of the bore. The method may further comprise applying a force to the housing adjacent the opening to cause deformation and reduce a size of the opening. In some examples, there is further provided a deformation tool for deforming a housing of a linear movement system. The deformation tool may comprise a first section comprising a cylindrical body and a flat end surface. The deformation tool may further comprise a second section comprising a radially-extending protrusion, which extends radially relative to the first section, at an end opposite to the flat end surface, the radially-extending protrusion comprising a surface forming an angle, relative to the flat end surface. In some examples, there is further provided a linear slider housing of a linear movement system, and a linear movement system. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a flowchart of a method for retaining a bush within a housing; Figure 2 shows another flowchart of a method for retaining a bush within a housing; Figure 3 shows an example of a deformation tool; Figure 4 shows an example of the deformation tool of figure 3, when applied to a housing with a linear bush inserted therein; and Figure 5 shows an example of a linear movement system. Detailed Description The disclosure relates to a way of retaining a bush with a housing. The housing may be used in the context of a linear movement system, such as a linear slider or actuator. Linear actuators, such as those to which the present method relates, may include a guide shaft and a housing, partially or completely surrounding the guide shaft, wherein the housing may be moved along the guide shaft by appropriate movement control means. In order to facilitate smooth and reliable movement, the housing and guide shaft may have a bush, such as a tubular-shaped bush or glacier bush, positioned inside the housing, between the housing and guide shaft. A lubricant may be applied between the guide shaft and bush to further ensure smooth operation and longevity of the respective parts. The bush may sit within a recess inside the housing, such that there is little or no movement between the housing and the bush, but the guide shaft may easily pass through the centre of the bush, and the housing. The guide shaft may typically have a cylindrical shape. The housing may thus comprise a round bore hole, through which the guide shaft may pass, and the central hole of the bush may be sized to allow controlled but smooth movement of the guide shaft therethrough. In accordance with the present disclosure, there is provided a method for retaining a substantially tubular bush within a housing of a linear movement system, as shown in figure 1. The housing in this method may comprise a bore into which the tubular bush is insertable. The method may comprise inserting S101 the tubular bush through an opening into the bore, such that an outer surface of the tubular bush faces a substantially cylindrical inner wall of the bore. The method may further comprise applying S102 a force to the housing adjacent the opening to cause deformation and reduce a size of the opening. In some examples, the force is applied to the end face of the housing, at a position near the bore opening. The contact point, through which the force or load is applied may be adjacent or at the bore opening edge. The contact point may be moved to achieve the desired deformation of the housing, for example based on the material of the housing, to ensure consistent deformation of the housing without damage to the housing, such as a split. The deformation may for example be permanent or plastic deformation, such that the bush is retained within the housing once the force is removed. In some examples, the force may be distributed around a periphery of the opening. By distributing the force around the periphery, a consistent deformation of the housing, and reduction in size of the opening, may be achieved, leading to more reliable retention of the bush within the housing. The opening may be reduced in size by 0.25mm. For example, the diameter at the opening may be reduced in size by 0.25mm or less, such as 0.1mm. The deformation may in practice not be, or may be barely, visible on the housing. The bore may be a through hole, extending through the housing. The method may further comprise, as shown in figure 2, inserting S203 a second tubular bush through a second opening, at an opposite end of the bore from the opening into which the tubular bush is inserted, such that a second outer surface of the second tubular bush faces the substantially cylindrical inner wall of the bore. The method may further comprise applying S204 a force to the housing adjacent the second opening to cause deformation and reduce a size of the second opening. In some examples, a tubular bush may be inserted at both ends of the housing bore, to further improve smooth movement of along a guide shaft. The force may be applied to the housing by applying a force to the deformation tool. The force may be applied using a hydraulic press. In some examples, the force may be applied by a hydraulic press. As an example, the amount of force may be 2.5 tons, 5 tons, 7 tons or 8.5 tons, but other amounts are envisaged. More specifically, the amount of force may be proportional to the size of the Linear Shift Mechanism (LSM) bore. In some examples, if the diameter of the LSM bore is 38mm, a force of 2.5 tons may applied. If the LSM bore diameter is 64mm, a force of 5 tons may be applied. If the LSM bore diameter is 100mm, a force of 7 tons may be applied. If the LSM bore diameter is 150mm, a force of 8.5 tons may be applied. The force applied is to ensure appropriate deformation of the housing and, consequently, the size of the opening, such that the bush is held in place, but the bush is not itself deformed. The force may be applied using a deformation tool 10. The deformation tool 10 may be any suitable tool, such as those described in detail below. The deformation tool 10 may be positioned, during application of the force, between the press, such as a hydraulic press, and the housing. The press may be used to apply the force to the housing, by pressing the deformation tool into the surface of the housing. An advantage of using such a deformation tool 10 is that the press, which can be very expensive, may be the same press for multiple different sizes of housing, and different deformation tools may be used for each different size of housing. In a specific example, there is further disclosed, as shown in figure 3, a deformation tool 10 for deforming a housing of a linear movement system. The deformation tool 10 may comprise a first section 11 comprising a cylindrical body 12 and a flat end surface 13. The deformation tool 10 may further comprise a second section 15 comprising a radially-extending protrusion 16, which extends radially relative to the first section 11, at an end opposite to the flat end surface 13, the radially-extending protrusion 16 comprising a surface 17 forming an angle, relative to the flat end surface 13. In some examples, the angle of the surface 17 relative to the flat end surface 13 may be 30 degrees. In other words, the angle may be 60 degrees relative to a side 14 of the cylindrical body 12 of the first section 11. The first section 11 may comprise a chamfer 18 between the cylindrical body 12 and the flat end surface 13. Such a chamfer 18 may help to locate the deformation tool 10 for insertion into a bore of the housing. That is to say, the diameter of the cylindrical body 12 of the first section 11 may be only slightly smaller than the diameter of the bore in the housing or a central hole of the tubular bush. Therefore, chamfering may be used to assist the user in locating the tool 10 at or near the middle of the bore / hole, such that the cylindrical body 12 and the bore / hole are substantially coaxial. The flat end surface 13 may in some examples be flat, so that the tool 10 easily rests on its end surface when not in use, but in other examples may have any suitable shape. The deformation tool 10 may comprise the first section 11 for extending into the bore and into a centre of the tubular bush, when positioned within the bore. The first section 11 may centre the deformation tool 10 relative to the housing, i.e. in the centre of the bore in the housing. The first section 11 may ensure that movement of the bush is reduced and that the force, applied to the housing, is applied at a uniform distance from the central axis of the deformation tool 10, the bush and the housing bore. This has the advantage that the opening may be reliably reduced in size by a desired amount. The deformation tool 10 may comprise the second section 15 comprising a radially extending protrusion 16 to abut the housing, adjacent the opening. The radially extending protrusion 16 may for example be a flange. The deformation tool 10 may be shaped so that, when applying the force to the housing adjacent the opening, the deformation and reduction in the size of the opening is caused. The shape of the deformation tool 10 may include an inclined surface 17 facing the opening so that, when applying the force to the housing adjacent the opening, the deformation and reduction in the size of the opening is caused. The inclined surface 17 may extend from a position over the end face of the housing, such that the end face of the housing is contacted first, with the inclined surface extending inwards (towards the central axis) and away from the end face of the housing, such that the deformation of the end face of the housing directs the housing material inwards, to retain the bush within the bore. In one example, the deformation tool 10 may including an inclined surface 17, inclined at approximately 60 degrees relative to the side 14 of the cylindrical body 12 of the first section 11. In this example, the cylindrical body 12 may have a diameter of 19.90mm. A contact point of the inclined surface 17 (i.e. where the inclined surface contacts the end face of the housing to apply force and cause deformation) may have a diameter of 24.20mm. In other words, the contact point may be 12.10mm from the central axis of the tool 10. In such an example, the inner diameter of the tubular bush 3, into which the cylindrical body 12 is inserted, may be 19.99mm. The outer diameter of the tubular bush 3 may be 22.99mm. Deformation caused by applying force using the deformation tool 10, in the manner described, reduces the size of the opening of the bore 2 to less than 22.99mm in this example. Thus, the opening and potentially the end of the bush 3 may be "pinched" and thereby retained within the bore 2 or within a seat, suitable for accommodating the bush 3, in the housing. In this example, to achieve the required deformation, a force of 4 tons may be applied to the deformation tool 10. The second section 15 may comprise a second end surface, opposite the end surface 13 of the first section 11, that may also be flat, on which the press may apply the force, or any suitable shape. In some examples the deformation tool 10 may be a swaging tool. The size and shape of the first section 11 may be dependent on the size and shape of the bush 3. In many applications, the bush 3 may be cylindrical, tubular or sleeve-shaped so as to sit in a bearing seat within a housing 1, while allowing relative linear movement of a part along the inner surface of the bush 3. The housing 1 may be any suitable housing, but may in some examples be a bearing housing, including a round through-hole into which a shaft, such as a guide shaft, may be inserted, so as to be linearly moveable along the bush 3. In some examples, the flange 16 may be a radially extending load application section, which is arranged to translate a load, applied to the tool 10, to the bearing housing 1 adjacent a hole into which the bush 3 is inserted. In this way, when a load is applied to the tool 1, the load is applied to the housing 1 so as to deform the entrance of the hole inwards and make the hole smaller, so as to retain the bush 3 within the hole. The end of the tool 1, opposite the first section 11, may be any suitable shape for receiving the applied load / force for causing the swaging of the housing 1. There is further disclosed, as shown in figure 4, a linear slider housing 1 for use in a linear movement system 5. The linear slider housing 1 may comprise a guide bore 2 into which a tubular bush 3 is inserted, such that an outer surface of the tubular bush 3 faces a substantially cylindrical inner wall of the bore 2. An area 4 of the linear slider housing 1 adjacent an opening of the guide bore 2 may be deformed such that the opening is reduced in size and the tubular bush 3 is retained within the guide bore 2. There is further disclosed, as shown in figure 5, a linear movement system 5. The linear movement system 5 may comprise the linear slider housing 1 as described above. The area of the linear slider housing 1 adjacent the opening of the guide bore 2 may be deformed by the deformation tool 10 as described above. In some examples the deformation tool 10 may comprise stainless steel. The flange may be shaped to extend radially by a distance greater than the thickness of the bush 3, so as to contact the housing 1. Between the cylindrical body 12 and the angled surface 17, the flange may comprise a flat surface, so as to avoid contact with the housing 1 or bush 3 in the space between the cylindrical body 12 and the angled surface 17. This avoids undesired deformation of the bush 3 or the housing 1. Further, with an angled surface 17 as described above, the flange may have a flat end surface parallel to the side of the cylindrical body 12, to promote deformation of the housing inwards, towards the bush 3, rather than radially outwards. In some examples, the flange may comprise bumps, ridges, mounds or a single ridge extending the circumference of the flange. As shown in figure 5, there may be provided a linear movement system 5, linear shift system or mechanism, or linear translator. Such a system 5 may be configured to allow for controllable, linear movement of parts. The linear shift system 5 may comprise a handwheel 6 connected to a leadscrew 7, configured to allow for controllable movement along the leadscrew 7, by turning the handwheel 6, in the axial direction of the leadscrew 7. An attachment may be moved along the leadscrew 7, by turning the handwheel 6. This provides one example, however further mechanical or electrically controlled movement control devices may be provided to control movement of the leadscrew 7. There may be further provided an anti-rotation shaft 8, located on one side of the leadscrew 7, wherein the attachment may be connected across the leadscrew 7 and anti-rotation shaft 8, to move along the leadscrew 7 and the anti-rotation shaft 8 in the axial direction, by turning the handwheel 6, in one example. There may further be provided a guide shaft 2, which may be located on an opposite side of the leadscrew 7 to the anti-rotation shaft 8, but other arrangements are envisaged. The attachment may be connected across the leadscrew 7, anti-rotation shaft 8 and the guide shaft 2, to move in the axial direction, by turning the handwheel 6. The axes of the leadscrew 7, anti-rotation shaft 8 and the guide shaft 2 may be oriented in parallel. There may further be a bellows assembly 9. The linear shift system 5 may be attachable to an enclosure within which it is desirable to allow for movement of parts located within the enclosure, but where the enclosure may be in a vacuum or clean state, such that there is no fluid connection between inside and outside the enclosure. Therefore, a bellows assembly 9 may include a device or attachment to carry out the movement of the part, inside the enclosure while maintaining the fluid seal to preserve the vacuum or clean environment within the enclosure. The bellows assembly 9 may, at one end, be connected to the enclosure and may, at an opposite end, be connected to the attachment, such that, when in use, the attachment, through rotation of the handwheel 6, moves axially along the anti-rotation shaft 8, leadscrew 7 and guide shaft 2 while compressing or expanding the bellows 9 and moving the device or attachment positioned inside the bellows 9 to be in fluid contact with the inside of the enclosure. As described above, there is disclosed, methods and devices used to apply a force to an end of a bearing housing, adjacent a circular bore, into which the bearing or bush is inserted, so that a part of the bearing housing, at the entrance of the circular bore, is deformed, to retain the bearing within the circular bore. The deformation tool 10 may be a linear movement system housing deformation tool or a linear shift system housing deformation tool. While the above method sets out a number of steps taken in order, it will be understood that those steps may be carried out in any suitable order. The method is not limited to the order described above as will be understood by the skilled person. Various modifications of the invention are of course possible. For example, the invention may be embodied either in a linear shift mechanism or any other suitable device. Any of the features described in the enclosed claims may be combined with any features of any other claims.

Images