1. Technical Field
The present invention relates to a telescopic cover used for covering guiding surface of machine or apparatus, such as machining tool or three-dimensional measuring instrument, while being attached to the machine or apparatus so as to protect their internal mechanical structures.
2. Related Art
Machining tool or three-dimensional measuring instrument is generally provided with a linearly-driven machining head or a measuring unit or the like, and is therefore configured to have a rail-form or shaft-form guiding surface over the range of travel of the machining head and so forth, so as to allow the machining head to travel in a reciprocating manner along the guiding surface. However, adhesion of cutting debris or dust discharged during machining onto the guiding surface may adversely affect accuracy of linear movement of the machining head, or may be causative of disorder. For the purpose of protecting the guiding surface of the machining head and so forth from the dust and so forth, there has therefore been used a telescopic cover having a plurality of protection covers which are arranged in a nested manner, and linked with each other with the aid of a linking mechanism which is composed of a plurality of linking elements. The telescopic cover stretches and shrinks in association with linear travel of the machining head or the like, typically while being fixed on the base side thereof to the main unit of the machining tool, and fixed on the end side thereof to the machining head or the like.
One known telescopic cover is proposed by the present applicant (see Japanese Utility Model Gazette No. 3133056). The telescopic cover has a plurality of protection covers, wherein a guide rail which has a guide groove is fixed to each protection cover. On the other hand, in the vicinity of the end of each linking element which configures the linking mechanism, there is fixed a connecting shaft having the top end thereof engaged in the guide groove of the guide rail. On the upper end side of the connecting shaft, there is formed a disk which slidingly contacts the inner wall of the guide groove.
Sliding resistance, however, generates when the inner wall of the guide groove and the outer circumferential surface of the disk are brought into contact with each other, or when the linking mechanism moves and thereby the connecting shaft moves in the direction normal to the direction of stretching of the telescopic cover. One idea for reducing the sliding contact may be such as providing a single rolling element to the connecting shaft. It is supposed that such provision of a single rolling element to the connecting shaft may allow smooth travel of the connecting shaft, while preventing sliding contact between the inner wall of the guide groove and the rolling element.
However, in the thus-configured telescopic cover, the protection cover disposed most closely to the based side (or end side in some cases) out of the plurality of protection covers may be fixed to an inaccurate position of machine or apparatus, such as machining tool, while being slightly inclined in the vertical direction or transverse direction, or may be applied with an external force in a distorting direction even if it should be fixed to an accurate position. If the center axis (connecting shaft) of the rolling element inclines away from the depth-wise direction of the guide groove as a consequence, a part of the outer circumferential surface of the rolling element may come into contact with both of one guiding surface and the other guiding surface opposed therewith, which compose the guide groove, enough to make the rolling element no more roll, and make it locked. As a matter of course, the locking of the rolling element makes the linking mechanism disabled as a whole, and the telescopic cover can no more stretch and shrink. The machining tool, however, keeps on generating operating force, so that either one of, or both of the machining tool and the telescopic cover may accidentally be broken. While a method of setting of a large (wide) clearance between the outer surface of the rolling element and the guide groove is supposed to be effective in view of avoiding the nonconformity, the method is not successful in accurately guiding the rolling element (connecting shaft) in the direction normal to the direction of stretching of the telescopic cover.
The present invention is proposed to solve the above-described problems in the conventional telescopic cover, wherein an object of which is to provide a novel telescopic cover capable of constantly keeping a rolling state of the rolling element without causing locking of the rolling element on the guiding surface of the guide groove, even if it is inclined away from the depth-wise direction of the guide groove while being applied with external force in a distorting direction, and consequently capable of stably repeating the stretching and shrinking motion.
According to a first aspect of the present invention (invention described in claim 1), there is provided a telescopic cover having a plurality of protection covers each having a top plate and a vertically-suspended plate vertically suspended from the top plate, and being arranged so as to cover a guiding portion of a machining tool or the like in a freely stretchable manner between every adjacent pair of the protection covers, while being linked with each other by a linking mechanism which is configured by a plurality of linking elements linked so as to be rotatable around connecting shafts. The telescopic cover has a plurality of guide rails provided to the plurality of protection covers, each having a guide groove which has one and the other guiding surfaces opposed with each other, in the direction normal to the direction of stretching of the entire portion of the protection covers; and a plurality of rolling elements arranged in the guide groove, so as to be freely rotatable around each connecting shaft which extends in the depth-wise direction of the guide groove.
According to the telescopic cover of the first aspect of the present invention, each guide groove formed in a plurality of guide rails is brought into contact with a plurality of rolling elements which are freely rotatable around each connecting shaft, so that frictional resistance, which may generate during stretching and shrinkage of the protection covers corresponded to stretching and shrinkage of the linking mechanism in association with linear travel of machine or apparatus, such as machining tool, may effectively be reduced. Even when the entire portion of, or a part of the protection covers are applied with external force in a distorting direction, and thereby the connecting shafts incline away from the depth-wise direction of the guide groove, the telescopic cover of the present invention can constantly keep a rolling state of a plurality of rolling elements without causing locking of the rolling elements on the guiding surface of each guide groove, and can consequently repeat the stretching and shrinking motion.
According to the telescopic cover of the present invention, since each guide groove has one and the other guiding surfaces opposed with each other, and since each connecting shaft extends in the depth-wise direction of the guide groove, so that even when the connecting shafts are forced to incline away from the depth-wise direction of the guide groove, a part of the plurality of rolling elements comes into contact with one guiding surface, and the other part of the rolling elements always comes into contact with the other guiding surface, so as to keep all rolling elements rotated in both directions. Of course, when all of the plurality of rolling elements rotates while being brought into contact with only either one guiding surface or the other guiding surface, all of the plurality of rolling elements rotate in the same direction. Anyway, an accidental state, in which the plurality of rolling elements are locked in each guide groove and made no more rollable therein, and thereby the linking mechanism and the protection cover as a whole are inhibited to stretch or shrink, may be avoidable in a successful manner.
The rolling element may be good enough if it can rotate around the connecting shaft, while being brought into contact with at least one and the other guiding surfaces of the guide groove, when the linking mechanism stretches or shrinks (and consequently the plurality of protection covers stretch or shrink as a whole) and thereby the connecting shaft moves in the direction normal to the direction of stretching or shrinkage. For example, the rolling element may be configured to have a disk form having the connecting shaft fixed thereto or inserted therethrough at the center thereof, or may be configured as a bearing which is composed of an outer cylinder formed into a cylindrical shape, an inner cylinder fixed at the center thereof to the connecting shaft, and a plurality of balls disposed between the outer cylinder and the inner cylinder.
According to a second aspect of the present invention (invention described in claim 2) , there is provided the telescopic cover as described in the first aspect, wherein each of the guide rails further has: an opening formed between the one and the other guiding surfaces so as to allow the connecting shafts inserted thereinto; and a closing portion opposed with the opening, the width of the inner surface of the closing portion which configures the guide groove is smaller than the diameters of the plurality of rolling elements.
According to the second aspect of the present invention, the width of the inner surface of the closing portion which configures the guide groove is set smaller than the diameters of the plurality of rolling elements, so that even if the rolling element closest to the inner surface of the closing portion, out of the plurality of rolling elements, approaches the inner surface of the closing portion while being applied with an external force, the rolling element does not contact over a wide area rolling element rolling element with the inner surface, when it moves in the longitudinal direction of the guide rail. As a consequence, according to the telescopic cover of the second aspect of the present invention, the frictional resistance between the rolling element and the inner surface of the closing portion may be reduced, and thereby smoother stretching and shrinkage of the linking mechanism, and the protection covers as a whole, may be ensured.
4A;
1 telescopic cover
2, 3, 4, 5 first to fourth protection covers
2
a,
3
a,
4
a,
5
a top plates
6 linking mechanism
8, 9, 10, 11 vertically-suspended plates
14, 15, 16, 17, 18 guide rails
15
a horizontal closing plate
15
b left vertically-suspended plate
15
c right vertically-suspended plate
19 to 24 first to sixth connecting bars
31 to 39 first to ninth connecting shafts
51 first rolling element
52 second rolling element
A telescopic cover 1 according to a best mode of embodying the present invention will be detailed below, referring to the attached drawings. The telescopic cover 1 of this embodiment is fixed to a machining tool not illustrated.
The telescopic cover 1 is composed of iron, and has, as illustrated in
At the front lower ends of the first to fourth vertically-suspended plates 8, 9, 10, 11, there are fixed first to fourth guide rails 14, 15, 16, 17, respectively, in the direction normal to the direction of stretching of the first to fourth protection covers 2, 3, 4, 5 as a whole. On the top plate 5a of the fourth protection cover 5, there is fixed a fifth guide rail 18 in the same direction with the direction of stretching and shrinkage, while placing a base plate (reference numeral not given) in between.
The first protection cover 2 herein is an element fixed to the main unit of the machining tool not illustrated. On the other hand, the fourth protection cover 5 is an element fixed to a reciprocating machining head not illustrated. The second protection cover 3 is disposed inside the first protection cover 2, the third protection cover 4 is disposed inside the second protection cover 3, and the fourth protection cover 5 is disposed inside the third protection cover 4. The first to fourth protection covers 2, 3, 4, 5 are shaped so as to be nested one after another, which are step-wisely reduced in size in this order. Note that the mode of attachment of the telescopic cover 1 to the machining tool is not limited to the above-described one, and may be such that the smallest fourth protection cover 5 is fixed to the main unit of the machining tool, and the largest first protection cover 2 is fixed to the machining head reciprocating with respect to the main unit of the machining tool.
The thus-configured first to fourth protection covers 2, 3, 4, 5 are linked by the first to fourth guide rails 14, 15, 16, 17 each having a guide groove formed in the direction normal to the direction of stretching and shrinkage of the first to fourth protection covers 2, 3, 4, 5 as a whole; the fifth guide rail 18 having a guide groove formed in the direction of stretching and shrinkage of the fourth protection cover 5; first to sixth connecting bars (linking elements of the present invention) 19 to 24 disposed between every adjacent pair of the guide rails 14 to 18 so as to configure the linking mechanism 6; seventh and eighth guide bars 25, 26; first to ninth connecting shaft 31 to 39 respectively engaged, on the upper end sides thereof, with the guide grooves of the guide rails 14 to 18 so as to be slidable in the guide grooves, and respectively supporting, on the lower end sides thereof, the connecting bars 19 to 24 and the guide bars 25, 26 in a freely rotatable manner; and first to third supporting shafts 41, 42, 43 respectively supporting the middle portions of the connecting bars 19 to 24. When the fourth protection cover 5 reciprocates together with the machining head not illustrated, the second and third protection covers 3, 4 stretch and shrink between the stretched state illustrated in
The first to fourth guide rails 14, 15, 16, 17 are fixed to the first to fourth vertically-suspended plates 8, 9, 10, 11 on the lower front side thereof (on the right side) as illustrated in
The first to fourth guide rails 14, 15, 16, 17 are configured similarly to the second guide rail 15 illustrated in
The first to ninth connecting shafts 31 to 39 are configured similarly to the third connecting shaft 33 illustrated in
Above the flange 33c (on the side opposite to the bar connecting rod 33) , there is formed a diameter-enlarged portion 33d having a diameter slightly increased from the outer diameter of the bar connecting rod 33, above which the (first and second) rolling elements 51, 52 which compose the present invention are disposed in a freely rotatable manner. More specifically, in this embodiment, two (first and second) rolling elements 51, 52 are provided to the third connecting shaft 33 (the same will apply also to the first and second connecting shafts 31, 32, and to the fourth to ninth connecting shafts 34 to 39). Both of the first and second rolling elements 51, 52 are composed of stainless steel, formed into a cylindrical geometry, and have insertion holes 51a, 52a bored at the centers thereof, so as to allow the insertion rod 33b, which configures the third connecting shaft 33, to be inserted therethrough. The outer diameters of the first and second rolling elements 51, 52 are respectively set smaller than the distance between the inner surface (rolling surface) of the left vertically-suspended plate 15b and the inner surface (rolling surface) of the right vertically-suspended plate 15c which compose the second guide rail 15 (the width of the guide groove). In other words, a slight clearance is formed between the guide groove of the second guide rail 15 and the outer circumferential surfaces of the first and second rolling elements 51, 52. On the upper end of the insertion rod 33b of the third connecting shaft 33, a bolt 54 is screwed in the threaded portion (nut portion) thereof. The bolt 54 is configured by a disk-form head 54a and a stem 54b, wherein the outer diameter of the head 54a is set smaller than the width of the lower surface of the horizontal closing plate 15a, and set smaller than the outer diameters of the first and second rolling elements 51, 52. The stem 54b is threaded on the outer circumferential surface thereof to form the other threaded portion (reference numeral not given) which is engageable with the above-described one threaded portion formed on the inner circumferential surface of the recess 33e.
The first to sixth connecting bars 19 to 24, and the seventh and eighth guide bars 25, 26 are arranged as described below. As illustrated. in
Similarly, the fifth and sixth connecting bars 23, 24 are arranged to form an X-pattern, and connect the third guide rail 16, with the aid of the fifth and sixth connecting shaft 35, 36, to the fourth guide rail 17, with the aid of the seventh and eighth connecting shafts 37, 38, while being supported at the X-form intersection with the aid of the third supporting shaft 43. The seventh and eighth guide bars 25, 26 are arranged to form a V-pattern, and connect the fourth guide rail 17, with the aid of the seventh and eighth connecting shafts 37, 38, to the fifth guide rail 18 with the aid of the ninth connecting shaft 39.
Accordingly, when the fourth protection cover 5 moves to the −X side in association with motion of the machining head not illustrated, the third protection cover 4 is moved to the −X side with the aid of the fifth and sixth connecting bars 23, 24. When the third protection cover 4 thus moves, the second protection cover 3 moves to the −X side with the aid of the third and fourth connecting bars 21, 22, while leaving the first protection cover 2 which is fixed to the main unit of the unillustrated machining tool unmoved, so that the first connecting shaft 31 moves to the +Y side, and the ninth connecting shaft 32 moves to the −Y side.
At the same time, the third, fifth and seventh connecting shafts 33, 35, 37 move to the +Y side, the fourth, sixth and eighth connecting shafts 34, 36, 38 move to the −Y side, and the ninth connecting shaft 39 moves to the −X side. As a consequence, upon movement of the fourth protection cover 5 to the −X side, the distance between every adjacent pair of the protection covers 2, 3, 4, 5 reduces to give a state more similar to that illustrated in
Positional relation of the first and second rolling elements 51, 52 with respect to the first to fourth guide rails 14, 15, 16, 17 will further be detailed below. When the telescopic cover 1 as a whole shrinks from the stretched state illustrated in
Unlike the case where the telescopic cover 1 normally stretches or shrinks, while keeping both of the first rolling element 51 and the second rolling element 52 rolled on the one guiding surface or the other guiding surface composing the guide groove, any of the first to fourth protection covers 2, 3, 4, 5 composing the telescopic cover 1 may be applied with external force, so that the connecting shaft 33, having been vertically positioned in the depth-wise direction of the guide groove as illustrated in
In the telescopic cover 1 of this embodiment, the guide groove of each of the first to fourth guide rails 14, 15, 16, 17 has first to fourth stoppers (bolts) 57, 58, 59, 60 provided thereto, as illustrated in
Although the (for example, second) guide rail (15) and the (third) connecting shaft (33) of the telescopic cover 1 of this embodiment have been explained referring to those configured as illustrated in
A guide rail 70 illustrated in
In the guide rail 70, one end of a connecting shaft 71 is inserted. The connecting shaft 71 is positioned so as to connect the individual connecting bars 20,21 in a freely rotatable manner, similarly to the first to ninth connecting shafts 31 to 39, and has a bar connecting rod 71a which connects the individual connecting bars, and an insertion rod 71b which is integratedly formed with the bar connecting rod 71a, inserted into the guide rail 70, and provided therearound with the rolling elements described later. The connecting shaft 71 has a disk-form outer flange 71c which is formed between the bar connecting rod 71a and the insertion rod 71b, has a diameter larger than the diameters of the bar connecting rod 71a and the insertion rod 71b, and is positioned outside the guide rail 70, and a disk-form inner flange 71d which is formed above the outer flange 71c, has a diameter slightly smaller than the outer diameter of the outer flange 71c, and is positioned in the guide groove. Around the outer periphery of the insertion rod 71b and above the inner flange 71d, there are disposed the first and second rolling elements 51, 52 in a freely rotatable manner. A snap ring 73 is fixed to a middle position of the upper end of the insertion rod 71b, and a flat washer 74 is disposed below the snap ring 73 and on the first rolling element 51, and also between the first rolling element 51 and the second rolling element 52. The outer diameters of the first and second rolling elements 51, 52 are set slightly smaller than the distance between the left vertically-suspended plate 70b and the right vertically-suspended plate 70c, so as to ensure a clearance between the guide groove and the first and second rolling elements 51, 52.
Also for the case having the guide rail 70, the connecting shaft 71 and the first and second rolling elements 51, 52 configured as described in the above, if the connecting shaft 71 having been vertically positioned in the depth-wise direction of the guide groove inclines as illustrated in
Number | Date | Country | Kind |
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2009-170401 | Jul 2009 | JP | national |