JP2003269568A - Linear motion device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] A rolling element can be circulated with good operability while reducing noise. The linear motion device has a relief groove (20b) at the bottom of a screw groove (20a), and a tongue (11) has a projection (11).
a from the rolling element passage of the thread groove 20a
0b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion device in which a guide shaft and a movable body relatively move while circulating a rolling body.

[0002]

2. Description of the Related Art FIG. 8 is a perspective view showing a tube circulation type ball screw device (hereinafter, simply referred to as a ball screw device) 50 as a linear motion device by cutting away a part thereof. As shown in FIG. 8, the ball screw device has a semi-circular cross-section on a screw shaft (guide shaft) 60 that has a semi-circular cross-section screw groove (rolling element rolling groove) 60a and extends in the axial direction. A ball nut (movable body) 70 having a thread groove (rolling element rolling groove) 70a is fitted. The thread groove 60a of the screw shaft 60 and the thread groove 70a of the ball nut 70 are opposed to each other, and through the rolling of a large number of rolling elements 80 as rolling elements filled between the thread grooves 60a, 70a. The screw shaft 60 and the ball nut 70 can be relatively moved in the axial direction (for example, the ball nut 70 is linearly moved by the axial rotation of the screw shaft 60). Along with this movement, the rolling element 80 also moves in both screw grooves 60.
Although it moves while rolling in the spiral passage formed by a and 70a, in order to continuously move the ball nut 70, these rolling elements 80 must be infinitely circulated.

Therefore, the thick portion of the ball nut 70 is tangentially communicated with the spiral passage and the screw shaft 60 is provided.
Circulation hole 7 that is a pair that straddles the nut and is opened to the outside of the nut
1, 71 are formed and the circulation holes 71, 71 are connected by a substantially U-shaped return tube 90 serving as a ball circulation member to form a ball circulation path 72 (in the figure, two ball circulation paths 72 are provided). Provided). The circulation path formed by the parts having the scooping portion is also used in the linear guide device.

[0004]

(1) Problems in a state where the tongue tip collides With FIG. 9, a return tube 90 and screw grooves 60a, 70 are shown.
The partial cross-section of a is shown. As shown in FIG. 9, a tongue-shaped projection (hereinafter referred to as a tongue portion) 91 provided at an end of the return tube 90 scoops up the rolling element 80 and guides the rolling element 80 into the return tube 90. There is. In the linear guide device, the rolling elements are guided in a circulation means such as an end cap.

As shown in FIG. 10, the tongue portion 91 and the thread groove 60a generally have an outer periphery as shown in FIG.
The positional relationship is such that there is some clearance with a. Further, in order to provide strength, the tip 91a of the tongue portion 91 has a thickness of about ¼ or more of the wall thickness of the return tube 90. That is, as shown in FIG. 11B, when the thickness of the return tube 90 is a and the thickness of the tip 91a of the tongue portion 91 is b, b / a ≧
The wall thickness is 1/4. Thereby, as compared with the case where the tip 91a of the tongue portion 91 has an acute angle as shown in FIG. 11 (A), it is possible to prevent damage due to hitting the rolling element 80.

It is ideal that the rolling element 80 and the tongue portion 91 contact with each other at the surface of the tongue portion 91 and at the point of the rolling element 80, but if the scooping angle becomes smaller, the tongue portion will come into contact. 91 and the rolling element 80 have collided at points. Here, the scooping angle is as shown in FIG.
As shown in FIG. 2, it refers to an angle α formed by the tangent line L12 of the moving track L1 at the intersection of the moving track L1 of the rolling element 80 and the center line L2 of the return tube 90 and the center line L2. For example, when the rake angle is 0 °,
The angle α formed by the tangent line L12 and the center line L2 is 0 °.
The scooping in this case is so-called tangential scooping.

When the rake angle defined as described above is small and the tongue portion 91 and the rolling element 80 hit each other at the points, the surface pressure at the hit point becomes high, which causes wear and scratches on the rolling element 80. In addition, since the rolling element 80 sunk under the tongue portion 91, a force to lift the return tube 90 upward is generated. Further, when the rolling element 80 is in the form of slipping under the tongue portion 91, the problem that the rolling phenomenon of the rolling element 80 becomes large occurs.

[0008] At present, in order to cope with the speeding up, etc., the strength of the entire tongue portion 91 is changed to a stronger material or the material thickness is increased, but the cost is increased. Often connected. Further, even if such an improvement is carried out, the contact state between the tongue portion 91 and the rolling element 80 does not change, so that the generation of friction or scratches on the rolling element 80 is not improved. (2) Issues of tangential line scooping and scooping by low scooping angle However, in the conventional art, by reducing the scooping angle, the rolling element 80 is guided to the return tube 90 in the tangential direction of the movement track and added to the entire tongue portion 91. The power is being reduced. That is, since the dynamic movement direction of the rolling element 80 is not changed, it is ideal that the scooping of the rolling element is tangential scooping.

However, the tongue portion 91 and the rolling element 80
From the relationship with, tangential line scooping is not always good. 13 (A) shows the positional relationship between the tongue portion 91 and the rolling element 80 when the scooping angle is large, and FIG. 13 (B) shows the tongue portion 91 and the rolling element 80 in the case of tangential scooping. The positional relationship is shown. As shown in FIGS. 13A and 13B, the angle change at the scooping portion at the center of the rolling element 80 is naturally advantageous in the case of tangential scooping, but the passage locus of the tongue portion 91 and the rolling element 80. Looking at the step (that is, the boundary between the tongue portion 91 and the thread groove 60a), the step becomes large in the case of tangential scooping. This is not good in terms of operability and noise.

(3) Problems when using a holding piece On the other hand, in recent years, a ball screw device or a linear guide device with a holding piece has been proposed as a means for reducing the competition between rolling elements. The holding piece 100 is shown in FIG.
As shown in FIG. 4, it is formed in an annular shape and is sandwiched between the rolling elements 80, 80 in the circulation path, and prevents the rolling elements 80, 80 from coming into contact with each other when the rolling elements 80 circulate in the device. It is a thing.

FIG. 15 shows a ball screw device in which the holding piece 100 is filled. The holding piece 100 is shown in FIG.
As shown in FIG. 5, when the rolling elements 80 located on both sides of the rolling element 80 are held without a gap, it is possible to flexibly follow the angle change according to the circulation path shape. Here, the filling clearance of the holding piece 100 becomes a problem. The filling clearance is an interval (clearance) between the rolling element 80 and the holding piece 100 when the holding piece 100 is filled in the circulation path. Normally, the filling clearance is, for example, 0 to 20% (that is, 20% at maximum) with respect to the diameter of the rolling element.

However, if this filling clearance becomes large,
Since the rolling piece 80 does not hold the holding piece 100, the holding piece 100 has to move independently in the circulation path, and there is a high possibility that it will be caught in a clearance or a step in the circulation path. Therefore, if the clearance or step between the return tube 90 and the thread groove 60a is large, the holding piece 100 will be caught by such clearance or step as shown in FIG. Such a problem becomes prominent in the case of tangential scooping with a large step and scooping with a low scooping angle.

When the holding piece 100 is caught in the circulation path, for example, the operability of the holding piece 100 including the rolling elements 80 is deteriorated, or in the worst case,
The holding piece 100 may be damaged. In order to eliminate this, the filling clearance is controlled, and its standard value (for example, as described above, the filling clearance is 0 to 20).
%I have to. ) Had to be strict. (4) Problems due to changes in angle near the tongue part From this, it is considered preferable that the scooping angle is large to some extent. However, when the scooping angle becomes large, the angle change becomes large in the vicinity of the tongue portion 91, which increases wear of the rolling elements and noise due to deterioration of operability, and problems such as clogging are more likely to occur. May cause a vicious circle in which the wear of the tongue portion 91 progresses. However, in order to prevent this, it is necessary to highly manage the dimensional accuracy of the scooped-up parts, which leads to an increase in cost.

Therefore, the present invention has been made in view of the above various problems, and an object thereof is to provide a linear motion device capable of circulating rolling elements with good operability while reducing noise.

[0015]

In order to solve the above-mentioned problems, a linear motion device according to a first aspect of the present invention is a linear motion device having a first rolling element rolling groove and an axially extending guide shaft, and the first linear motion device. Has a second rolling element rolling groove facing the rolling element rolling groove, and the guide shaft is provided through rolling of a plurality of rolling elements between the first and second rolling element rolling grooves. Between the first and second rolling element rolling grooves and a position between the movable body which is guided by the relative movement relative to the guide groove and the first and second rolling element rolling grooves. And a circulating means for returning the rolling element to another position between the first and second rolling element rolling grooves by scooping up the rolling element moving by the scooping portion. In this linear motion device, the scooping portion is located in a rolling element passage of the first rolling element rolling groove, and the scooping portion is provided at the bottom of the first rolling element rolling groove. In the above, a relief recess is formed so as to make the portion facing the bottom portion non-contact.

That is, regarding the relationship between the scooping portion and the guide shaft, the portion having the scooping portion at the bottom of the first rolling element rolling groove is not in contact with the relief recess of the first rolling element rolling groove. It has such a relationship. Here, as the portion of the scooping portion that faces the bottom of the first rolling element rolling groove, a protruding portion that projects from the scooping portion can be mentioned.
Further, a groove shape can be used as the escape recess.

According to a second aspect of the present invention, there is provided the linear movement device according to the first aspect, wherein the depth position of a portion of the scooping portion facing the bottom portion is the recessed recess from the lower end of the rolling element passage cross section. It is characterized by existing inside. That is, the linear motion device according to claim 1 includes a state in which the portion of the scoop-up portion facing the bottom of the first rolling element rolling groove is not located in the escape recess. The linear motion device according to claim 3 is the same as that according to claim 1.
In the linear motion device according to the second aspect, a holding piece interposed between the rolling elements is movably filled between the first and second rolling element rolling grooves and the circulation means, The holding piece is filled such that the distance between the rolling element and the holding piece between the first and second rolling element rolling grooves and in the circulation means is at most 200% of the maximum diameter of the rolling element. It is characterized by

Conventionally, the maximum distance is about 20% of the diameter of the rolling element. This is to prevent the holding piece from catching on the tip of the scooping portion if it exceeds 20%. In the invention according to claim 1, it is possible to prevent the holding piece from being caught on the tip of the scooping portion. Therefore, in the invention according to claim 3, the distance is maximum and 200% of the maximum diameter of the rolling element is provided. The holding piece is filled so that

The linear motion device according to claim 4 is the linear motion device according to any one of claims 1 to 3, wherein another member is attached to the scooping portion, and the other member is the above-mentioned member. A feature of the scooping portion is that a portion facing the bottom portion is formed. That is, by making the scooping part a double structure using other members,
The shape of the scooping portion is such that the tip thereof is present from the rolling element passing cross section of the rolling element rolling groove of the guide shaft to the inside of the escape recess.

The linear motion device according to claim 5 is the linear motion device according to any one of claims 1 to 4, characterized in that the circulating means is formed of a metal material or a resin material. There is.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. This embodiment is a tube circulation type ball screw device (hereinafter,
It is simply called a ball screw device. ) Is applied to the present invention. This ball screw device basically has a structure similar to that of the ball screw device 50 shown in FIG. Due to the application of the present invention, the shape of the return tube and the shape of the screw shaft are different from the conventional ones.

In the ball screw device 50 shown in FIG. 8, the screw shaft 60 has a screw groove 60a, which is a first rolling element rolling groove, and corresponds to a guide shaft extending in the axial direction. 70 has a thread groove 70a that is a second rolling element rolling groove that faces the thread groove 60a.
through the rolling of the plurality of rolling elements 80 between a.
It corresponds to a movable body which is guided by and moves relative to the screw shaft 60. The return tube 10 to which the present invention is applied has a substantially U-shape as shown in FIG.
Tongue portions 11 and 11 are provided at each end of the rolling element 80 that forms an inlet portion or an outlet portion. For example, the return tube 10 is manufactured using a metal material or a resin material. The tongues 11 and 11 are integrally formed with protrusions 11a and 11a at their ends. For example, as shown in FIG. 2, the shape of the protrusion 11a is similar to the thread groove 20a and the clearance groove 20b, and is substantially semicircular.

The return tube 10 has a thread groove 6
0a, 70a from one position to the screw grooves 60a, 70
The rolling element 80 moving between a is scooped up by the tongue portion 11 which is a scooping portion, and the rolling element 80 is screwed into the thread groove 6
It corresponds to a circulation means for returning to another position between 0a and 70a. On the other hand, as shown in FIG. 2, the screw shaft 20 is formed with a screw groove 20a having a substantially semicircular cross section, and further, a groove portion 20b is formed at the bottom of the screw groove 20a. The radius of curvature of the thread groove 20a is substantially equal to the radius of the rolling element 80.

As shown in FIG. 2, the groove portion 20b is an escape groove which is an escape recess formed so that the protrusion 11a of the tongue portion 11 can enter, and has a substantially semicircular groove shape. For example, the shape of the groove portion (hereinafter referred to as the escape groove) 20b is
It is formed along the bottom of the thread groove 20a and has a width of 50% or less of the diameter of the rolling element 80 and a depth of 50% or less of the diameter of the rolling element 80. In addition, the escape groove 20
The boundary portion (or the connecting portion) between b and the thread groove 20a may be R-shaped or chamfered.

The tongue portion 11 is provided in the clearance groove 20b.
The projection 11a of the tongue 11 allows the projection 11a to escape, but in detail, the tongue 1
As shown in FIG. 3, the clearance area of the first protrusion 11a is a non-contact area (hatched area A) with the rolling element 80 including the clearance groove 20b at the bottom of the thread groove 20a. As shown in FIG. 3, notches 11b may be formed at both ends of the outer periphery of the tongue portion 11 in order to prevent stress concentration.

As described above, in the ball screw device, the tongue portion 11 is located in the rolling element passage or the rolling element passage cross section of the thread groove 20a, and the tongue portion 11 faces the bottom portion of the thread groove 20a. A protrusion 11a is formed on the bottom of the thread groove 20a.
An escape groove 20b for making the contactless is formed.
That is, the tip end of the tongue portion 11 has a shape that exists from the lower end of the rolling element passage of the thread groove 20a to the inside of the clearance groove 11a by forming the protrusion 11a. In other words, a gap between the tongue portion 11 and the thread groove 20a (a non-contact portion between the tongue portion 11 and the thread groove 20a) is formed at a position as far as possible from the rolling element center passage path.

With the above-described structure, the tip of the tongue portion 11 escapes from the lower end of the rolling element passage of the thread groove 20a.
By making the shape so that it exists over the inside of b, the step difference in the vicinity of the scooping up of the tongue portion 11 can be reduced. Thereby, the operability of the rolling element 80 can be improved, the passing sound when the rolling element 80 passes through the tongue portion 11 can be suppressed, and low noise can be realized. Further, since the rolling element 80 is less damaged when passing through the step, the life of the rolling element 80 can be increased.

The relief groove 20b of the thread groove 20a can also function as a reservoir for lubricant such as grease. Further, since the protrusion 11a of the tongue portion 11 scoops out the grease accumulated in the escape groove 20b, the scooped-out grease has a lubricating effect on the rolling element 80 in the circulating means. . Further, since the structure has no catch, the catch of the holding piece can be prevented even when the holding piece is used. Therefore, the present invention effectively works for a ball screw device including a holding piece. Further, since the filling clearance of the holding piece in the circulation path can be made large, the filling management of the holding piece becomes easy.

For example, when the filling clearance becomes large, as shown in FIG.
As shown in FIG. 6, the play of the holding piece 100 in the circulation path becomes large, and the holding piece 100 may be caught by the tip of the tongue portion 91. Like the present invention,
By eliminating the step between the tongue portion 10 and the thread groove 20a,
Since the structure can be prevented from being caught, it is possible to prevent the holding piece 100 from being caught on the tip of the tongue portion 91 in this way.

Further, as a result, the filling clearance management value of the holding piece 100 is made larger than the present holding piece filling clearance (clearance of 0 to 20% of the maximum diameter of the rolling element) (the maximum diameter of the rolling element). It can be used with a clearance of 0 to 200%). If the filling clearance is set to about 20% of the diameter of the rolling element in the case of an ordinary design product, a locking phenomenon particularly occurs at low speed rotation, but the present invention can prevent such a holding piece from being caught. As a result, the filling management of the holding piece is simplified. In addition, the filling clearance control value of the holding piece 100 is the maximum diameter 0 of the rolling element.
~ 100% is desirable.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. That is, in the above-described embodiment, the shapes of the tongue portion 11 and the protrusion portion 11a thereof have been described by way of specific examples, but the shape is not limited thereto. As shown in FIGS. 4 and 5, parts may be attached to the tongue portion 11. As shown in FIG. 4, a member 31 having a protrusion 31 a protruding from the tip of the tongue portion 11 may be attached to the tongue portion 11 so as to be arranged on the back surface of the tongue portion 11.

Further, as shown in FIG. 5, a member 32 extending from the inner surface of the return tube 10 to the tongue portion 11 may be attached. And this member 32
In addition, a protrusion 32 a protruding from the tip of the tongue portion 11 is provided. By attaching the members 31 and 32 shown in FIGS. 4 and 5 to the tongue portion 11, as described above, the protrusions 3 of the members 31 and 32 are fitted into the clearance grooves 20b of the thread groove 20a.
Since 1a and 32a can be positioned, the same effect as the above-mentioned effect can be obtained. Further, in addition to such an effect, the portion of the tongue 11 on which the rolling element 80 abuts and the tip portion can be processed with priority on the shape, and further, regarding the member 32 of FIG. 5, the strength against the rolling element 80 hitting. Return tube 10 (tongue 1
You can take charge of it in 1). This allows
The design of the return tube 10 or the tongue portion 11 can be made flexible.

Further, in the above-described embodiment, the tongue portion 1
The case where the first protrusion 11a has a shape similar to the shape of the escape groove 20b of the screw groove 20a has been described, but the present invention is not limited to this. That is, for example, as shown in FIG. 6, the protrusion 11a of the tongue portion 11 may have a pointed shape.
In short, the shape of the tip of the tongue portion 11 may be any shape that allows the tongue portion 11 to enter the escape groove 20b. Further, in the above-described embodiment, the case where the thread groove 20a has a curved shape has been described with reference to FIG. 3, but the invention is not limited to this. For example, as shown in FIG. 7, the thread groove 20a may have a triangular groove shape. According to such a thread groove 20a, the contact between the rolling element 80 and the thread groove 20a is not a surface contact or a line contact, but two point contact.

In such a case, the clearance area of the projection 11a of the tongue portion 11 is, as shown in FIG. 7, the rolling element 80 including the clearance groove 20b at the bottom of the thread groove 20a.
Is a non-contact area (hatched area A). Further, in the above-described embodiment, the case where the escape recess has a shape along the bottom of the thread groove 20a has been described, but the present invention is not limited to this. For example, the escape recess may have a hole shape formed in a predetermined section at the bottom of the thread groove 20a.

Further, in the above-mentioned embodiment, the projection 11
The case where a is located in the escape groove 20b has been described, but the invention is not limited to this. That is, since the escape groove 20b is formed, the protrusion 11a is formed in the thread groove 20.
It suffices if contact with the bottom of a can be avoided. As a result, for example, the protrusion 11a is provided with the escape groove 20b
Although it does not enter the inside, the projection 11a has the escape groove 20b.
The case where it is located immediately before is also included.

Further, the relief recess has a function as a grinding relief. In this case, it can be said that the relief recess effectively utilizes such a grinding relief. Further, in the above-described embodiment, the case where the present invention is applied to the ball screw device has been described, but a structure in which a rolling element is scooped up from a screw groove such as a roller screw device, a linear guide device, or a ball spline or a guide groove. It can also be applied to the adopted device.

In the above embodiment, the case where the circulation means is the return tube has been described, but the present invention can be applied to other circulation means such as end caps, side caps and tops.

[0038]

As described above, according to the first aspect of the present invention, the relationship between the scooping portion and the guide shaft is such that the portion of the bottom of the first rolling element rolling groove facing the bottom portion of the scooping portion. By making the relationship such that the first rolling element rolling groove does not come into contact with the relief concave portion, it is possible to eliminate the step near the scooping portion. This improves operability, reduces noise and vibration, and reduces friction, for example.

Further, according to the second aspect of the present invention, the portion of the scooping portion facing the bottom of the first rolling element rolling groove is located in the escape recess, so that the step near the scooping portion is surely achieved. I'm losing. Further, according to the invention described in claim 3, by utilizing the fact that the holding piece is prevented from being caught at the scooping portion, the clearance between the rolling element and the holding piece in the circulation path is maximum and the maximum diameter of the rolling element is maximum. Of 2
It is set to 00%. This simplifies filling management of the holding piece, for example.

According to the invention described in claim 4, the scooping portion has a double structure, and the tip of the scooping portion extends from the lower end of the rolling element passage of the rolling element rolling groove of the guide shaft into the escape recess. By doing so, it is possible to give a degree of freedom to the design of the lifting portion that facilitates the circulation means such as the return tube. That is, for example, where the scooping portion requires precision, it can be advantageous in manufacturing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the shape of a return tube.

FIG. 2 is a sectional view showing a protrusion of a tongue portion and a clearance groove of a screw groove.

FIG. 3 is a diagram used for explaining a clearance area when the screw groove of the screw shaft has an R surface shape.

FIG. 4 is a view showing a tongue portion to which another member constituting a protrusion is attached.

FIG. 5 is a view showing a tongue portion to which another member forming a protrusion is attached.

FIG. 6 is a cross-sectional view showing a tongue portion having a protrusion of another shape.

FIG. 7 is a diagram used for explaining an escape area when the screw groove of the screw shaft has a planar shape.

FIG. 8 is a perspective view showing a configuration of a ball screw device.

FIG. 9 is a sectional view showing a partial configuration of a return tube and a thread groove in the related art.

FIG. 10 is a cross-sectional view showing a tongue portion and a thread groove in the related art.

FIG. 11 is a cross-sectional view used for explaining a case where a tip portion of a tongue portion has a predetermined thickness.

FIG. 12 is a view used for explaining a scooping angle.

FIG. 13 is a diagram used to explain the behavior of the rolling elements depending on the scooping angle.

FIG. 14 is a diagram showing a relationship between a holding piece and a rolling element.

FIG. 15 is a view showing an operating state of the ball screw device when the holding piece is filled.

FIG. 16 is a view showing a state where the holding piece is caught on the tip of the tongue portion.

[Explanation of symbols]

10,90 Return tube 11 tongue 11a protrusion 11b Notch 20 screw shaft 20a Thread groove (shaft) 20b escape groove 31, 32 Parts that form protrusions 31a, 32a Protrusions by other members 50 ball screw device 60 screw shaft 60a Thread groove (shaft) 70 ball nut 70a Thread groove (nut) 71 Circulation hole 72 Circulation path 80 rolling elements 91 Tongue 91a Tip of tongue part 100 holding piece Claim of A tongue tip position L1 Rolling center movement start L2 Return tube center line L12 L1 tangent α scooping angle

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Claims (5)

[Claims] 1. A guide shaft which has a first rolling element rolling groove and extends in the axial direction, and a second shaft which faces the first rolling element rolling groove.
A rolling element rolling groove, and is guided by the guide shaft through rolling of a plurality of rolling elements between the first and second rolling element rolling grooves to be opposed to the guide groove. From a position between the moving movable body and the first and second rolling element rolling grooves,
And circulation means for returning the rolling element to another position between the first and second rolling element rolling grooves by scooping up the rolling element moving between the second rolling element rolling grooves by the scooping portion. In the linear motion device, the scooping portion is located in a rolling element passage of the first rolling element rolling groove, and the first rolling element rolling groove has a bottom portion thereof, A direct-acting device, characterized in that an escape concave portion is formed in the scooping portion so as to make a portion facing the bottom portion non-contact. 2. The linear motion device according to claim 1, wherein a depth position of a portion of the scooping portion facing the bottom portion is present from a lower end of the rolling element passage cross section to inside the escape recess. 3. A holding piece interposed between the rolling elements is movably filled between the first and second rolling element rolling grooves and in the circulation means, and the holding piece comprises: The space between the first and second rolling element rolling grooves and the distance between the rolling element and the holding piece in the circulating means are maximum so as to be 200% of the maximum diameter of the rolling element. The linear motion device according to claim 1 or 2, characterized in that. 4. The other member is attached to the scooping portion, and the other member forms a portion of the scooping portion that faces the bottom portion. Direct acting device described in. 5. The circulating means is formed of a metal material or a resin material.
The linear motion device according to any one of 1.