JP3893832B2 - Feed unit device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a feed unit device that can be suitably used by being incorporated in, for example, an operating arm of a robot or an XY table, and more particularly to a seal structure that prevents foreign matter from entering the inside of a guide rail that houses a slider.
[0002]
[Prior art]
As a conventional feed unit device, for example, there is one described in Japanese Utility Model Publication No. 7-28444. This feed unit device is a combination of a so-called ball screw and a linear motion guide device, which has two side walls and a bottom plate, that is, a slider is housed inside a guide rail having a U-shaped cross section, and on the outer surface. A screw shaft having a ball screw groove is inserted into the slider, and is arranged inside the guide rail so that its axial direction is parallel to the longitudinal direction of the guide rail, and the ball screw groove of the screw shaft, A large number of rolling balls are interposed between the opposing ball screw grooves of the slider, and the axial ball rolling grooves formed on the inner surface of each side wall of the guide rail are opposed to the ball rolling grooves. When a large number of rolling balls are interposed between the ball rolling grooves of the slider and the screw shaft is rotated, the numerous balls are formed between the ball screw groove of the screw shaft and the ball screw shaft of the slider. Rolling and said plan The large number of balls roll between the ball rolling groove of the rail and the ball rolling groove of the slider so that the slider is moved in the longitudinal direction of the guide rail inside the guide rail. is there. The slider is provided with a projecting portion that projects above the two side walls, and a flexible thin plate sealing member is placed on the inner upper surface of the projecting portion, and the inside of the guide rail, that is, the slider is covered with the thin plate sealing member. Is covered in the longitudinal direction between the two side walls. A rubber magnet projecting inward from each side wall protrudes below the thin plate seal member, and adsorbs metal foreign matters that are about to enter the inside of the guide rail from between the thin plate seal member and both side walls. Like to do. Incidentally, the rubber magnet has a thin plate shape that is long in the longitudinal direction of the guide rail, and is inserted into and fixed to a slit formed on the side wall of the guide rail. With the above configuration, high sealing performance can be obtained.
[0003]
On the other hand, as another example of the feed unit device, there has been proposed one in which a seal structure is simplified and a thin plate-like seal portion is provided to protrude from the side surface of the slider to the upper end surface of each side wall.
[0004]
[Problems to be solved by the invention]
However, the seal structure of the feed unit described in the above publication has a problem that the configuration is complicated, the number of parts is large, and the cost is high. In addition, the slit on the side wall of the guide rail into which the thin rubber magnet is inserted has to be machined at least at the present stage, and there is a problem that the cost increases accordingly.
[0005]
Further, as described above, a thin plate-like seal portion projecting from the side surface of the slider to the end surface of each side surface of the guide rail has a low sealing effect and substantially prevents foreign matter from entering the inside of the guide rail. I can't.
The present invention has been developed to solve these various problems, and is a feed unit device that is easy to configure, has a small number of parts, can reduce costs, and can ensure sufficient sealing performance. Is intended to provide.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the feed unit device of the present invention accommodates a slider inside a guide rail having two side walls and a bottom plate, and a screw shaft having a ball screw groove on the outer surface. And is arranged inside the guide rail so that its axial direction is parallel to the longitudinal direction of the guide rail, and the ball screw groove of the screw shaft and the ball screw groove of the slider facing the screw shaft In between, a large number of rolling balls are interposed, between the axial ball rolling groove formed on the inner surface of each side wall of the guide rail, and the ball rolling groove of the slider facing it, When a number of rolling balls are interposed and the screw shaft is rotated, the number of balls roll between the ball screw groove of the screw shaft and the ball screw shaft of the slider, and the ball rolling of the guide rail Groove and slider In the feed unit device in which the slider is moved in the longitudinal direction of the guide rail by rolling the numerous balls between the guide rail and the guide rail, the guide is guided from the slider. A seal portion that protrudes on the end surface of each side wall of the rail opposite to the bottom plate and that is long in the longitudinal direction of the guide rail is provided. , characterized in that located in the bottom plate opposite the Ri by the inner end surface side of the end face of each side wall of the guide rail the guide rail longitudinal tip of and the bending portion is provided a curved portion of the outwardly convex Is.
[0007]
When the slider is composed of a combination of a slider main body and end caps attached to both ends in the longitudinal direction, the sealing portion is separated from the slider, and a locking claw is formed on the sealing portion. When an engagement groove is formed in the cap, the seal portion is applied to the side surface of the slider body, and end caps are attached to both end surfaces in the longitudinal direction of the slider body, the locking claws of the seal portion are formed in the engagement groove of the end cap. The seal portion may be fixed to the slider by engaging.
[0008]
Further, at least the protruding tip portion of the seal portion may be made of a flexible material.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a feed unit device of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of a feed unit device according to the present embodiment. FIG. 1a is a plan view, FIG. 1b is a longitudinal sectional view, and FIG. 1c is a ZZ sectional view of FIG. The guide rail 1 is substantially U-shaped in cross section, and is extended on the inner surface of both side walls 1a raised from the bottom plate 1c with one ball rolling groove 2 extending in the longitudinal direction at the opposing position. Bearing plates 3 and 4 are screwed to both ends of the guide rail 1 in the longitudinal direction. A ball bearing 31 is attached to the bearing plate 3, and a ball bearing 32 is attached to the bearing plate 4 in a double manner. Supported by these bearings 31, 32, the screw shaft 7 of the ball screw is arranged parallel to the ball rolling groove 2 at the center of the width of the guide rail 1, that is, parallel to the longitudinal direction of the guide rail 1. . One shaft end 7a of the screw shaft 7 protrudes outward from the bearing plate 4 and can be connected to an output shaft of a drive motor (not shown). In the figure, reference numeral 33 denotes an outer ring presser of the bearing 32, and reference numeral 34 denotes an inner ring fixing nut of the bearing 32. In FIG. 1, the ball screw grooves 7b and 12 are shown in a simplified form.
[0010]
A slider (nut) 8 of a tube circulation type ball screw is screwed onto the screw shaft 7 via a steel ball (not shown) and is housed inside the guide rail 1 having a substantially U-shaped cross section. . The slider 8 includes a square slider main body 9 and end caps 10 fixed to the front and rear sides thereof, that is, at both ends in the longitudinal direction of the guide rail 1 with bolts. As clearly shown in FIG. 2, a ball screw groove 12 corresponding to the ball screw groove 7 b of the screw shaft 7 is formed on the inner peripheral surface of the screw hole 11 formed at the center of the slider body 9. . The ball is inserted into a ball rolling path composed of both ball screw grooves 7b and 12. In addition, a U-shaped ball circulation tube 13 is inserted into the tube mounting hole 9a (FIG. 2) at the lower part of the slider body 9 so that the scooping portions provided at both ends face the ball rolling path. The ball is lifted up from the ball rolling path through the tube mounting hole 9a (FIG. 2) to the ball circulation tube 13, and then returns from the ball circulation tube 13 to the ball rolling path and circulates internally. It has a well-known tube circulation structure.
[0011]
The width of the slider body 9 is slightly smaller than the inner dimension between the both side walls 1a of the guide rail 1, and the balls opposed to the ball rolling grooves 2 of the guide rail 1 are formed at the lower portions of the left and right side surfaces. A rolling groove 14 is formed. Further, a linear ball return passage 15 parallel to the ball rolling groove 14 is formed in the slider thickness. A screw hole 30 with a guide hole for determining the position of an end cap 10 to be described later and attaching it is formed on the longitudinal end face of the slider body 9.
[0012]
As shown in FIGS. 3 and 4, a semi-doughnut-shaped curved path 20 that connects the ball rolling groove 14 and the ball return path 15 is formed on the joining end face of the end cap 10 joined to the slider body 9. Is formed. The semi-doughnut-shaped configuration of the curved path 20 will be described. A large-diameter semicircular recess 20a is formed on the joining end face of the end cap 10, and the center of the opening of the semicircular recess 20a is orthogonal to the opening. This is a known configuration in which a small-diameter semi-cylindrical recess 20b is formed and a semi-cylindrical return guide 19 is fitted into the semi-cylindrical recess 20b.
[0013]
In this way, at the lower part of the slider 8, a straight line comprising the ball rolling groove 2 of the guide rail 1 and the ball rolling groove 14 opposed thereto, the ball return passage 15, and the curved paths 20, 20 at both ends. A ball infinite circulation path of a guide system is configured, and a large number of balls (not shown) are rotatably mounted in the ball infinite circulation path. One end of the curved path 20 is formed as a scooping protrusion 22 for scooping up the ball 21 from the ball rolling groove 2 of the guide rail and guiding it smoothly to the curved path 20.
[0014]
A through hole 21 for inserting the screw shaft 7 is formed at the center of the end cap 10. Further, a guide projection 23 to be inserted into the guide hole of the screw hole 30 with the guide hole of the slider body 9 is projected from the end surface where the curved path 20 is formed, and the screw hole is formed at the center thereof. An insertion hole 24 for a bolt to be screwed onto 30 is formed.
[0015]
Engaging grooves 25 are formed at both ends in the width direction of the upper surface of the joint surface of the end cap 10 to the slider main body 9 to engage locking claws 37 of a seal member 35 to be described later. As shown in FIG. 5, the engaging groove 25 is a rectangular slit having a narrow width, and an engaging convex portion 25a is projected from the inner end portion thereof, and has a hook shape as a whole. .
[0016]
As shown in FIG. 6, the seal member 35 is formed of a long thin plate. Specifically, it is formed of a flexible material such as polyester elastomer represented by “Hytrel” (registered trademark, Toray DuPont Co., Ltd.). At both ends in the longitudinal direction of one end in the width direction of the seal member 35, hook-like locking claws 37 that fit into the engaging grooves 25 of the end cap 10 are projected. An engaging convex portion 38 that slightly protrudes is formed at the central portion of the locking claw 37 to increase the height of the locking claw 37. As a result, the thickness of the entire locking claw 37 is equal to or slightly thicker than the width of the engaging groove 25, and the locking claw 37 is tightly fitted into the engaging groove 25. Therefore, the end surface between the locking claws 37 of the seal member 35 is applied to the side surface of the slider main body 9, and the end cap 10 is fitted into the engagement groove 25 of the end cap 10 so that the end cap 10 is moved to the slider. When attached to the main body 9, the seal member 35 can be fixed to the slider 8 without an individual fastening member. The seal member 35 projects from the slider 8 onto the upper surface of the side wall 1a of the guide rail 1.
[0017]
As shown in each cross-sectional view of FIG. 7, the longitudinal cross section of the seal member 25 is a trapezoidal cross section in which the lower part of the end opposite to the side on which the locking claw 37 is formed widens. An arcuate groove 39 is formed, and the lower tip is sharpened. As will be described later, this lower tip portion contacts the upper surface of the side wall 1a of the guide rail 1 to form a seal, and therefore this lower tip portion is also referred to as a lip. Then, both end portions in the longitudinal direction of the seal member 35 are curved so that the width is gradually narrowed, and a curved portion 36 is formed here. The tip of the curved portion 36, that is, the narrowest portion of the seal member 35, when the seal member 35 is attached to the slider 8, as shown in FIG. It is located slightly inside the inner end face of the upper surface. That is, the curved portions 36 provided at both ends in the longitudinal direction of the seal member 35 are convex outward from the inside to the outside of the upper surface of the side wall 1a of the guide rail 1, strictly speaking, near the center.
[0018]
Next, the operation will be described.
When the screw shaft 7 is rotated forward (reverse) by the operation of a drive motor (not shown), the rotation of the screw shaft is interposed between the ball screw groove 7b of the screw shaft and the ball screw groove 12 of the slider. Is transmitted to the slider 8, and the slider 8 responds and moves forward (backward) in the axial direction. The rotation of the slider 8 itself is blocked by a linear guide system ball 21 interposed between the ball rolling groove 14 of the slider and the ball rolling groove 2 of the guide rail. Each ball 21 of both systems moves while rolling as the slider 8 moves, and circulates through the infinite circulation path of each system.
[0019]
As the slider 8 moves, the seal member 35, particularly the lip, moves along the upper surface of the side wall 1 a of the guide rail 1, and the curved portions 36 provided at both ends in the longitudinal direction are the side walls. Since it protrudes outward from the inner side to the outer side of the upper surface of 1a, for example, if there is a foreign object on the upper surface of the side wall 1a, it is paid out along the curved portion 36. Such foreign matters can be effectively removed from the fact that there are many such foreign matters in the inner portion of the upper surface of the side wall 1a, particularly near the slider 8. Further, since the curved portion 36 is located inside the upper surface of the side wall 1 a of the guide rail 1, foreign matter on the upper surface of the side wall 1 a does not enter the inside of the guide rail 1. Further, since the lip of the sealing member 35 is formed of a flexible polyester elastomer, the upper surface of the side wall 1a of the guide rail 1 is not rubbed and worn or damaged. In particular, the structure is such that the seal member 35 is sandwiched between the end caps 10 and fixed to the slider 8, so that the configuration is extremely easy and the cost can be reduced. Further, it is not necessary to change the structure for supporting the slider 8 in particular, and the support rigidity can be ensured.
[0020]
In addition, when the said sealing member 35 is made by injection molding, there may be a problem of the curvature after shaping | molding. In order to cope with this warp by correcting the shape of the entire mold, it is necessary to accurately predict how the warp is deformed, and it is difficult to eliminate warp after molding by this method. Further, the reinforcement of the ribs or the like makes the warpage uneven and makes it impossible to bring the entire lip into contact with the upper surface of the side wall 1 a of the guide rail 1. Although the magnitude of the warp is difficult to predict, the warp itself is due to the difference in residual stress between the front and back surfaces of the seal member 35 and has only a simple arc shape. Therefore, since the warpage tends to protrude downward as a whole in FIG. 6B, for example, the entire locking claw 37 is inclined so as to incline toward both ends, or contact with the engagement groove 25 of the end cap 10. By making one side to be inclined, a uniform deformation force is exerted over the entire area in the longitudinal direction of the seal member 35 from the attachment portion of the locking claw 37, that is, the seal member 35, thereby correcting the warp. Is desirable. According to this method, since the adjustment of the mold is performed only by the angle of the locking claw 37, a delicate adjustment can be easily realized.
[0021]
Polyester elastomers are originally made of the same material, but have various hardness grades. Therefore, for example, a soft material close to rubber can be used in the vicinity of the tip of the lip that requires a sealing function, and a hard material close to plastic can be used in the vicinity of the locking claw that requires support rigidity. In order to achieve this by injection molding, for example, a plurality of gates are formed for each material having different hardness, or a hard material is injected first, and then a soft material is injected (or conversely, a soft material is applied). After molding, a hard material may be molded). Since the hardness of the polyester elastomer is merely the difference in the ratio between the crystalline phase and the amorphous phase of the material, the bond at the boundary between the hard material and the soft material is extremely strong and there is no risk of separation.
[0022]
【The invention's effect】
As described above, according to the feed unit device of the present invention, a seal portion that protrudes from the slider on the end surface opposite to the bottom plate of each side wall of the guide rail and that is long in the longitudinal direction of the guide rail is provided. Protruding curved portions are provided on both ends in the longitudinal direction of the portion from the inside to the outside of the end surface, and the guide rail longitudinal ends of the curved portion are arranged on the opposite side of the bottom plate of each side wall of the guide rail . since located within Ri by the inner end face of the end face side, when the slider is moved in the longitudinal direction of the guide rail, the curved portion of the seal portion, the foreign matter on the end surface of the side wall of the guide rail from the inside to the outside of the end face In order to dispense, foreign matter close to the inside of the guide rail can be effectively eliminated, particularly at the end surface of the side wall of the guide rail, and it can be prevented from entering the inside of the guide rail. It is possible to achieve a cost reduction of the strike. In addition, the shape of the slider is simple, and the support rigidity of the slider does not decrease.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an embodiment of a feed unit device of the present invention, where (a) is a plan view, (b) is a longitudinal sectional view, and (c) is a ZZ sectional view.
FIG. 2 is a side view showing the slider main body of FIG.
3 is an explanatory view of the end cap of FIG. 1, wherein (a) is a plan view and (b) is a side view. FIG.
4 is an EE cross-sectional view of the end cap of FIG. 3;
5 is an explanatory view of an engagement groove of the end cap of FIG. 3, (a) is a detailed view, (b) is a GG sectional view, and (c) is a FF sectional view.
6 is an explanatory diagram of the seal member of FIG. 1, in which (a) is a plan view, (b) is a front view, and (c) is a right side view. FIG.
7 is a detailed explanatory view of the seal member of FIG. 6, in which (a) is a left side detailed view, (b) is an AA sectional view, and (c) is a BB sectional view.
[Explanation of symbols]
1 is a guide rail 1a, a side wall 1c, a bottom plate 2 is a ball rolling groove (of the guide rail)
7 is a screw shaft 7b is a ball screw groove (screw shaft)
8 is a slider 9 is a slider body 10 is an end cap 12 is a ball screw groove (slider)
14 is a ball rolling groove (slider)
15 is a ball return path (straight guide system)
21 is a ball (ball screw type)
25, the engaging groove 35, the sealing member 36, the curved portion 37, the locking claw

Claims (1)

A slider is housed inside a guide rail having two side walls and a bottom plate, a screw shaft having a ball screw groove on the outer surface is inserted into the slider, and its axial direction is parallel to the longitudinal direction of the guide rail. In this way, a large number of rolling balls are interposed between the ball screw groove of the screw shaft and the ball screw groove of the slider facing the screw shaft. When a large number of rolling balls are interposed between the axial ball rolling groove formed on the inner surface of each side wall and the ball rolling groove of the slider facing the axial rolling roller, The numerous balls roll between the ball screw groove of the screw shaft and the ball screw shaft of the slider, and the multiple balls also roll between the ball rolling groove of the guide rail and the ball rolling groove of the slider. By moving In the feed unit device in which the rider is moved in the longitudinal direction of the guide rail inside the guide rail, the rider projects from the slider onto the end surface of each side wall of the guide rail opposite to the bottom plate and A longitudinally long seal portion is provided, and at both ends in the longitudinal direction of the seal portion, a convex curved portion is provided outward from the inner side to the outer side of the end surface, and the guide rail longitudinal end portion of the curved portion is provided. feed unit apparatus being characterized in that located in the bottom plate opposite the inner end surface by Ri in the side of the end face of each side wall of the guide rail.

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