Patent Description:
A stretching machine configured to stretch a sheet, a film, or the like in a longitudinal direction and a transverse direction while conveying it has been known. For example, Patent Document <NUM> (<CIT>) discloses a simultaneous biaxial stretching machine in which longitudinal stretching and transverse stretching of a sheet-like object are performed simultaneously. The simultaneous biaxial stretching machine disclosed in Patent Document <NUM> includes endless link devices, and the endless link device includes equal-length link units formed like a folding scale.

The equal-length link unit disclosed in Patent Document <NUM> includes a plurality of rollers that are rotatably supported by bearings and move on the rails while rotating.

<CIT> relates to a drawing machine for sheet material.

<CIT> relates to an apparatus for biaxially stretching a film material.

In order to lengthen the maintenance interval of the stretching machine and reduce the maintenance frequency, it is desired to extend the life of the bearings used in the stretching machine.

Other problems and novel features will be apparent from the descriptions of this specification and accompanying drawings.

According to the present invention, a linkage mechanism is provided as defined in claim <NUM>.

Preferable features of the invention are defined in the dependent claims.

According to one embodiment, it is possible to extend the life of the bearings used in the stretching machine.

Hereinafter, an embodiment will be described in detail with reference to drawings. Note that the members having the same or substantially the same function are denoted by the same reference characters throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

<FIG> is a schematic diagram showing a configuration of a thin film manufacturing system including a stretching machine. A thin film manufacturing system <NUM> shown in <FIG> includes an extrusion apparatus (extruder, kneading extruder) <NUM>, a T-die <NUM>, a raw sheet cooling apparatus <NUM>, a stretching machine <NUM>, a take-off apparatus <NUM>, and a winder apparatus <NUM>.

In the thin film manufacturing system <NUM>, a thin film is manufactured through the following process. First, a raw material is supplied to a material supply unit (material supply port, hopper) 2a of the extrusion apparatus <NUM>. The raw material to be supplied to the extrusion apparatus <NUM> contains a resin material (for example, thermoplastic resin material in pellet shape), additives, and others. The raw material supplied to the extrusion apparatus <NUM> is conveyed (transported) while being kneaded (mixed). Specifically, the raw material supplied to the extrusion apparatus <NUM> is melt and kneaded while being sent forward by the rotation of a screw in the extrusion apparatus <NUM>. The raw material kneaded by the extrusion apparatus <NUM> (kneaded material) is supplied to the T-die <NUM>. The kneaded material supplied to the T-die <NUM> is extruded toward the raw sheet cooling apparatus <NUM> through a slit of the T-die <NUM>. The kneaded material supplied from the extrusion apparatus <NUM> to the T-die <NUM> is formed into a predetermined shape (in this case, film-like shape) by passing through the T-die <NUM>.

The kneaded material extruded from the T-die <NUM> is cooled and turned into a film <NUM> in the raw sheet cooling apparatus <NUM>. The film <NUM> is a resin film in a solidified state (solid state). More specifically, the film <NUM> is a thermoplastic resin film. The film <NUM> is continuously extruded from the T-die <NUM>. As a result, the film <NUM> is continuously supplied to the stretching machine <NUM>.

The film <NUM> supplied to the stretching machine <NUM> is stretched in an MD direction and a TD direction by the stretching machine <NUM>. The film <NUM> subjected to the stretching process (stretching treatment) by the stretching machine <NUM> is conveyed to the winder apparatus <NUM> via the take-off apparatus <NUM> and is wound by the winder apparatus <NUM>. The film <NUM> wound by the winder apparatus <NUM> is cut as appropriate.

The thin film manufacturing system <NUM> shown in <FIG> manufactures a thin film through the process described above. Understandably, the thin film manufacturing system <NUM> can be variously modified in accordance with the properties of the thin film to be manufactured. For example, an extraction tank may be provided near the take-off apparatus <NUM> shown in <FIG>, and the plasticizer (for example, paraffin or the like) contained in the film <NUM> may be removed in some cases.

The stretching machine <NUM> constituting the thin film manufacturing system <NUM> stretches the film <NUM> in the MD direction and the TD direction while conveying the film <NUM> in the MD direction. In other words, the MD (Machine Direction) direction is a conveying direction of the film <NUM>. Further, the TD (Transverse Direction) direction is the direction that intersects the conveying direction of the film <NUM>. Thus, in the following description, the MD direction is referred to as a "conveying direction" or a "longitudinal direction", and the TD direction is referred to as a "lateral direction" in some cases. The MD direction (conveying direction, longitudinal direction) and the TD direction (lateral direction) are the directions intersecting each other, and are more specifically the directions orthogonal to each other. Namely, the stretching machine <NUM> shown in <FIG> is a stretching machine capable of simultaneously stretching the film <NUM> in two directions intersecting each other while conveying the film <NUM>, and is referred to as a "simultaneous biaxial stretching machine" in general.

Next, the stretching machine <NUM> will be described in more detail. <FIG> and <FIG> are plan views schematically showing the structure of the stretching machine <NUM>. The stretching machine <NUM> includes a pair of link devices <NUM>. The pair of link devices <NUM> are arranged apart from each other in plan view. In the following description, one of the pair of link devices <NUM> is referred to as a "link device 10R" and the other of the pair of link devices <NUM> is referred to as a "link device <NUM>" for distinction in some cases. Understandably, such a distinction is merely for convenience of description.

In <FIG> and <FIG>, the link device 10R is arranged on the right side (R side) with respect to the conveying direction (MD direction), and the link device <NUM> is arranged on the left side (L side) with respect to the conveying direction (MD direction). The link device 10R and the link device <NUM> are separated from each other in the TD direction and face in the TD direction with the film <NUM> interposed therebetween. The film <NUM> is conveyed through the space between the link device 10R and the link device <NUM> in the MD direction. In other words, the space between the link device 10R and the link device <NUM> facing each other functions as a conveyance unit for conveying the film <NUM>.

With reference to <FIG>, the stretching machine <NUM> is divided into three regions 20A, 20B, and 20C in the conveying direction (MD direction). The region 20A serves as a preheating region, the region 20B serves as a stretching region, and the region 20C serves as a heat fixing region. The regions 20A, 20B, and 20C are arranged in this order in the conveying direction (MD direction).

The inlet of the film <NUM> in the stretching machine <NUM> (portion indicated by "IN" in <FIG> and <FIG>) exists in the region 20A. Also, the outlet of the film <NUM> in the stretching machine <NUM> (portion indicated by "OUT" in <FIG> and <FIG>) exists in the region 20C. Further, the region 20B in which the stretching process is performed is present between the region 20A in which the inlet of the film <NUM> exists and the region 20C in which the outlet of the film <NUM> exists.

A heat treatment unit <NUM> covers a part of the region 20A, all of the region 20B, and a part of the region 20C. Also, the heat treatment unit <NUM> covers the central parts of the link devices 10R and <NUM>, and heats the film <NUM> conveyed by the link devices 10R and <NUM>. The heat treatment unit <NUM> in this embodiment is composed of an oven capable of heating the film <NUM> to a desired temperature. The film <NUM> passes through the inside of the oven as the heat treatment unit <NUM> while being gripped by the link devices 10R and <NUM>.

As shown in <FIG> and <FIG>, each of the link devices 10R and <NUM> includes a plurality of link mechanisms <NUM> coupled so as to form an endless chain, and each of the link mechanisms <NUM> has a clip <NUM> which is a jig for gripping the film <NUM>. The film <NUM> is held by the clips <NUM> in the link mechanisms <NUM> constituting the link device 10R and the clips <NUM> in the link mechanisms <NUM> constituting the link device <NUM>. Namely, one side (R side/right side) of the film <NUM> is gripped by the plurality of clips <NUM> of the link device 10R, and the other side (L side/left side) of the film <NUM> is gripped by the plurality of clips <NUM> of the link device <NUM>.

Each of the link devices 10R and <NUM> further includes a pair of rails <NUM> and <NUM> arranged on a support table (bed) in addition to the plurality of link mechanisms <NUM>. In each of the link devices 10R and <NUM>, the rail <NUM> is arranged on an inner circumferential side, and the rail <NUM> is arranged on an outer circumferential side. Thus, the rail <NUM> is referred to as an "inner rail" and the rail <NUM> is referred to as an "outer rail" in some cases. Also, the rail <NUM> is referred to also as a "reference rail" or an "SP rail" and the rail <NUM> is referred to also as an "MD rail" in some cases.

The rails <NUM> and <NUM> provided in each of the link devices 10R and <NUM> are annularly arranged over the regions 20A, 20B, and 20C. More specifically, the rails <NUM> and <NUM> are turned back in the region 20A in which the inlet of the film <NUM> is present, are turned back in the region 20C in which the outlet of the film <NUM> is present, and are annularly arranged over the regions 20A, 20B, and 20C.

Three sprockets <NUM>, <NUM>, and <NUM> are provided inside the rail <NUM> of the link device 10R. Similarly, three sprockets <NUM>, <NUM>, and <NUM> are provided inside the rail <NUM> of the link device <NUM>. The sprockets <NUM> and <NUM> of the respective link devices 10R and <NUM> are arranged in the region 20A, and the sprockets <NUM> of the respective link devices 10R and <NUM> are arranged in the region 20C. However, the sprockets <NUM> and <NUM> are arranged outside the heat treatment unit <NUM> that covers a part of the region 20A. Further, the sprockets <NUM> are arranged outside the heat treatment unit <NUM> that covers a part of the region 20C. Namely, the sprockets <NUM>, <NUM>, and <NUM> of the respective link devices 10R and <NUM> are arranged outside the oven as the heat treatment unit <NUM>.

The plurality of link mechanisms <NUM> in the link devices 10R and <NUM> are arranged on the rails <NUM> and <NUM> in a state of being able to move along the rails <NUM> and <NUM>. The sprockets <NUM>, <NUM>, and <NUM> of the link device 10R shown in <FIG> engage with the plurality of link mechanisms <NUM> of the link device 10R. Therefore, when the sprockets <NUM>, <NUM>, and <NUM> rotate, a driving force acts on the plurality of link mechanisms <NUM> of the link device 10R, and the link mechanisms <NUM> move (run) along the rails <NUM> and <NUM> of the link device 10R. The sprockets <NUM>, <NUM>, and <NUM> of the link device <NUM> shown in <FIG> engage with the plurality of link mechanisms <NUM> of the link device <NUM>. Therefore, when the sprockets <NUM>, <NUM>, and <NUM> rotate, a driving force acts on the plurality of link mechanisms <NUM> of the link device <NUM>, and the link mechanisms <NUM> move (run) along the rails <NUM> and <NUM> of the link device <NUM>. Namely, the rails <NUM> and <NUM> of the respective link devices 10R and <NUM> are guide rails for moving (running) the plurality of link mechanisms <NUM> in a predetermined direction.

In the following description, for each of the link devices 10R and <NUM> shown in <FIG>, the side facing the film <NUM> is referred to as a "film side", and the side opposite to the film side is referred to as a "return side" in some cases. Namely, the side on which the plurality of link mechanisms <NUM> move from the inlet (IN) to the outlet (OUT) while the clips <NUM> are gripping the film <NUM> is the film side, and the side which is located on the opposite side of the film side and on which the plurality of link mechanisms <NUM> move from the outlet (OUT) to the inlet (IN) while the clips <NUM> do not grip the film <NUM> is the return side.

The pitch between the adjacent link mechanisms <NUM> (referred to as a "link pitch" in some cases) of the plurality of link mechanisms <NUM> changes in accordance with the interval (separation distance) between the rail <NUM> and the rail <NUM>. In other words, the pitch between the adjacent link mechanisms <NUM> can be adjusted by adjusting the separation distance between the rail <NUM> and the rail <NUM>.

<FIG> are plan views schematically showing the link mechanisms and the rails shown in <FIG>. As shown in <FIG>, the angle formed by the adjacent link mechanisms <NUM> becomes larger and the pitch P1 between the adjacent link mechanisms <NUM> becomes larger as the separation distance L1 between the rails <NUM> and <NUM> becomes smaller. On the other hand, the angle formed by the adjacent link mechanisms <NUM> becomes smaller and the pitch P1 between the adjacent link mechanisms <NUM> becomes smaller as the separation distance L1 between the rails <NUM> and <NUM> becomes larger.

As described above, each link mechanism <NUM> has the clip <NUM> configured to grip the film <NUM>. Therefore, the pitch P2 between the adjacent clips <NUM> also increases and decreases in accordance with the increase and decrease of the pitch P1 between the adjacent link mechanisms <NUM>. Specifically, the pitch P1 between the link mechanisms <NUM> increases when the separation distance L1 of the rails <NUM> and <NUM> decreases, and the pitch P2 between the clips <NUM> also increases when the pitch P1 between the link mechanisms <NUM> increases (<FIG> → <FIG>). On the other hand, the pitch P1 between the link mechanisms <NUM> decreases when the separation distance L1 of the rails <NUM> and <NUM> increases, and the pitch P2 between the clips <NUM> also decreases when the pitch P1 between the link mechanisms <NUM> decreases (<FIG> → <FIG>).

Since each of the plurality of link mechanisms <NUM> includes the clip <NUM>, the pitch P1 between the two adjacent link mechanisms <NUM> and the pitch P2 between the two clips <NUM> provided in these link mechanisms <NUM> are the same. Namely, P1=P2 holds in each of <FIG>.

The film <NUM> supplied from the raw sheet cooling apparatus <NUM> to the stretching machine <NUM> is gripped by the link devices 10R and <NUM> at the inlet of the stretching machine <NUM>. Specifically, the film <NUM> is gripped by the clips <NUM> provided in the link mechanisms <NUM> of the link devices 10R and <NUM> shown in <FIG> and <FIG>. More specifically, one side of the film <NUM> in the width direction is gripped by the clips <NUM> provided in the link mechanisms <NUM> of the link device 10R, and the other side of the film <NUM> in the width direction is gripped by the clips <NUM> provided in the link mechanisms <NUM> of the link device <NUM>.

The film <NUM> whose both sides in the width direction are gripped by the clips <NUM> is conveyed from the inlet to the outlet of the stretching machine <NUM> along with the movement of the link mechanisms <NUM> including the clips <NUM>, and passes through the region 20A (preheating region), the region 20B (stretching region), and the region 20C (heat fixing region) in this order. The film <NUM> is stretched in the MD direction and the TD direction while passing through the region 20B (stretching region). Thereafter, the film <NUM> reaches the outlet through the region 20C (heat fixing region) and is detached from the clips <NUM>. The film <NUM> detached from the clips <NUM> is conveyed to the take-off apparatus <NUM> and is further conveyed from the take-off apparatus <NUM> to the winder apparatus <NUM>.

As shown in <FIG>, in the region 20A (preheating region), the interval (separation distance in the TD direction) L2 between the rails <NUM> and <NUM> of the link device 10R and the rails <NUM> and <NUM> of the link device <NUM> is almost constant. Therefore, the stretching process of the film <NUM> in the TD direction is not performed in the region 20A. Accordingly, the width (dimension in the TD direction) of the conveyed film <NUM> does not change and remains constant in the region 20A.

Also, in the region 20A, the interval (separation distance) L1 between the rail <NUM> and the rail <NUM> of the link device 10R on the film side is almost constant. Therefore, in the region 20A, the pitch P1 of the link mechanisms <NUM> of the link device 10R on the film side is almost constant, and thus the pitch P2 of the clips <NUM> of the link device 10R on the film side is also almost constant. Further, in the region 20A, the interval (separation distance) L1 between the rail <NUM> and the rail <NUM> of the link device <NUM> on the film side is also almost constant. Therefore, in the region 20A, the pitch P1 of the link mechanisms <NUM> of the link device <NUM> on the film side is almost constant, and thus the pitch P2 of the clips <NUM> of the link device <NUM> on the film side is also almost constant. As a result, the stretching process of the film <NUM> in the MD direction is not performed in the region 20A. Namely, the stretching process of the film <NUM> in the TD direction and the MD direction is not performed in the region 20A.

Next, the operation of the stretching machine <NUM> in the region 20B will be described. In the region 20B, the interval (interval in the TD direction) between the rails <NUM> and <NUM> of the link device 10R and the rails <NUM> and <NUM> of the link device <NUM> gradually increases along the conveying direction (MD direction). Therefore, in the region 20B, the film <NUM> is pulled and stretched in the TD direction as it advances in the conveying direction (MD direction). In other words, in the region 20B, the width (dimension in the TD direction) of the film <NUM> gradually increases as it advances in the conveying direction (MD direction).

Also, in the region 20B, the interval (separation distance) L1 between the rail <NUM> and the rail <NUM> of the link device 10R on the film side gradually decreases along the conveying direction (MD direction), and the interval (separation distance) L1 between the rail <NUM> and the rail <NUM> of the link device <NUM> on the film side also gradually decreases along the conveying direction (MD direction). Therefore, in the region 20B, the pitch P1 of the link mechanisms <NUM> of the link device 10R on the film side gradually increases along the conveying direction (MD direction), and thus the pitch P2 of the clips <NUM> of the link device 10R on the film side also gradually increases. Further, in the region 20B, the pitch P1 of the link mechanisms <NUM> of the link device <NUM> on the film side gradually increases along the conveying direction (MD direction), and thus the pitch P2 of the clips <NUM> of the link device <NUM> on the film side also gradually increases. As a result, in the region 20B, the film <NUM> is pulled and stretched in the MD direction as it advances in the conveying direction (MD direction).

Therefore, in the region 20B, the film <NUM> is stretched in the TD direction and the MD direction as it advances in the conveying direction (MD direction). Namely, in the region 20B, the stretching process in the TD direction and the MD direction is applied to the film <NUM>.

Next, the operation of the stretching machine <NUM> in the region 20C will be described. In the region 20C, the interval (interval in the TD direction) between the rails <NUM> and <NUM> of the link device 10R and the rails <NUM> and <NUM> of the link device <NUM> is almost constant. Therefore, the stretching process of the film <NUM> in the TD direction is not performed in the region 20C. Accordingly, the width (dimension in the TD direction) of the conveyed film <NUM> does not change and remains constant in the region 20C.

Further, in the region 20C, the interval (separation distance) L1 between the rail <NUM> and the rail <NUM> of the link device 10R on the film side is almost constant. Therefore, in the region 20C, the pitch P1 of the link mechanisms <NUM> of the link device 10R on the film side is almost constant, and thus the pitch P2 of the clips <NUM> of the link device 10R on the film side is also almost constant. Further, in the region 20C, the interval (separation distance) L1 between the rail <NUM> and the rail <NUM> of the link device <NUM> on the film side is almost constant. Therefore, in the region 20C, the pitch P1 of the link mechanisms <NUM> of the link device <NUM> on the film side is almost constant, and thus the pitch P2 of the clips <NUM> of the link device <NUM> on the film side is also almost constant. As a result, the stretching process of the film <NUM> in the MD direction is not performed in the region 20C. Namely, the stretching process of the film <NUM> in the TD direction and the MD direction is not performed in the region 20C.

As described above, in the region 20A, the pitch P1 of the link mechanisms <NUM> of the link device 10R on the film side is kept constant, and the pitch P1 of the link mechanisms <NUM> of the link device <NUM> on the film side is also kept constant. Thereafter, in the region 20B, the pitch P1 of the link mechanisms <NUM> of the link device 10R on the film side and the pitch P1 of the link mechanisms <NUM> of the link device <NUM> on the film side are gradually expanded. Then, in the region 20C, the pitch P1 of the link mechanisms <NUM> of the link device 10R on the film side is kept constant again, and the pitch P1 of the link mechanisms <NUM> of the link device <NUM> on the film side is also kept constant again. Therefore, on the film side of each of the link devices 10R and <NUM>, the pitch P1 of the link mechanisms <NUM> in the region 20C is larger than the pitch P1 of the link mechanisms <NUM> in the region 20A. From another viewpoint, on the film side of each of the link devices 10R and <NUM>, the pitch P2 of the clips <NUM> in the region 20C is larger than the pitch P2 of the clips <NUM> in the region 20A. From still another viewpoint, on the film side of each of the link devices 10R and <NUM>, the separation distance L1 between the rails <NUM> and <NUM> in the region 20C is smaller than the separation distance L1 between the rails <NUM> and <NUM> in the region 20A.

<FIG> is a perspective view showing one of the plurality of link mechanisms shown in <FIG> in an enlarged manner. <FIG> is a cross-sectional view of the link mechanism shown in <FIG>.

As shown in <FIG> and <FIG>, each of the link mechanisms <NUM> provided in the link devices 10R and <NUM> includes an upper link plate <NUM>, a lower link plate <NUM>, a pair of rail holders 24a and 24b, and a base member <NUM> bridging the pair of rail holders 24a and 24b in addition to the clip <NUM>. One rail holder 24a is arranged on the rail <NUM>, and the other rail holder 24b is arranged on the rail <NUM>.

The upper link plate <NUM> and the lower link plate <NUM> are plate-shaped members that extend linearly in plan view. The base member <NUM> is common with the upper link plate <NUM> and the lower link plate <NUM> in that it extends linearly in plan view, but the base member <NUM> is thicker than these. In the following description, when the rail holders 24a and 24b are not particularly distinguished, they are collectively referred to as "rail holders <NUM>".

The rail holder 24a includes a roller holding portion 31a and a shaft 32a provided at the center of the roller holding portion 31a in the longitudinal direction. The roller holding portion 31a is arranged on the rail <NUM> so as to straddle the rail <NUM>. Therefore, one end of the roller holding portion 31a arranged on the rail <NUM> in the longitudinal direction protrudes toward the inner side of the rail <NUM> (side facing the rail <NUM>), and the other end of the roller holding portion 31a in the longitudinal direction protrudes toward the outer side of the rail <NUM> (opposite side of the side facing the rail <NUM>). Also, when the roller holding portion 31a is arranged on the rail <NUM>, the shaft 32a is located just above the rail <NUM>.

As shown in <FIG>, the shaft 32a of the rail holder 24a penetrates one ends of the upper link plate <NUM>, the lower link plate <NUM>, and the base member <NUM> in the longitudinal direction. A collar <NUM> is placed on the upper portion of the shaft 32a that penetrates one end side (base end side) of the base member <NUM> in the longitudinal direction and protrudes from the base member <NUM>. Annular engaging portions 33a and 33b are integrally formed on both sides of the collar <NUM> in the axial direction. A lower insertion portion of the collar <NUM> located outside the engaging portion 33b in the axial direction is inserted in a through hole provided at one end (base end) of the lower link plate <NUM> in the longitudinal direction, and the engaging portion 33b overlaps the peripheral edge portion of the through hole of the lower link plate <NUM>. Also, an upper insertion portion of the collar <NUM> located outside the engaging portion 33a in the axial direction is inserted in a through hole provided at one end (base end) of the upper link plate <NUM> in the longitudinal direction, and the peripheral edge portion of the through hole of the upper link plate <NUM> overlaps the engaging portion 33a. From another viewpoint, the base end of the base member <NUM>, the base end of the upper link plate <NUM>, and the base end of the lower link plate <NUM> are skewered with the shaft 32a, and are rotatably coupled with each other through the shaft 32a. In other words, the shaft 32a is a rotating shaft on the base end side of the upper link plate <NUM>, the lower link plate <NUM>, and the base member <NUM>.

The rail holder 24b includes a roller holding portion 31b and a shaft 32b provided at the center of the roller holding portion 31b in the longitudinal direction. The roller holding portion 31b is arranged on the rail <NUM> so as to straddle the rail <NUM>. Therefore, one end of the roller holding portion 31b arranged on the rail <NUM> in the longitudinal direction protrudes toward the inner side of the rail <NUM> (side facing the rail <NUM>), and the other end of the roller holding portion 31b in the longitudinal direction protrudes toward the outer side of the rail <NUM> (opposite side of the side facing the rail <NUM>). Also, when the roller holding portion 31b is arranged on the rail <NUM>, the shaft 32b is located just above the rail <NUM>.

The shaft 32b of the rail holder 24b penetrates one end (tip end) of the base member <NUM> in the longitudinal direction, and protrudes from the base member <NUM>. One ends (tip ends) of the upper link plate <NUM> and the lower link plate <NUM> in the longitudinal direction of another adjacent link mechanism <NUM> are rotatably coupled to the upper portion of the shaft 32b that protrudes from the base member <NUM> through a collar <NUM> similar to the collar <NUM>. Namely, the tip end of the base member <NUM> of the link mechanism <NUM> and the tip ends of the upper link plate <NUM> and the lower link plate <NUM> of another adjacent link mechanism <NUM> are rotatably coupled with each other through the shaft 32b of the link mechanism <NUM>. From another viewpoint, the shaft 32b is a rotating shaft on the tip end side of the upper link plate <NUM>, the lower link plate <NUM>, and the base member <NUM>.

The clip <NUM> is provided at the base end of the base member <NUM>. The clip <NUM> includes a main body portion <NUM>, a grip portion <NUM>, a spring portion <NUM>, and others. The main body portion <NUM> is fixed to the base end of the base member <NUM>. The grip portion <NUM> is attached to the main body portion <NUM> so as to operate vertically. The spring portion <NUM> biases the grip portion <NUM> so as to operate the grip portion <NUM> downward. By making the grip portion <NUM> operate downward by the biasing force of the spring portion <NUM>, the film <NUM> is sandwiched between the main body portion <NUM> and the grip portion <NUM>. Namely, the film <NUM> is gripped by the clip <NUM>. On the other hand, by making the grip portion <NUM> operate upward against the biasing force of the spring portion <NUM>, the film <NUM> is released from the clip <NUM>.

A pair of guide rollers 51a and 51b facing each other with the rail <NUM> interposed therebetween are provided in a lower portion of the rail holder 24a, and a pair of guide rollers 52a and 52b facing each other with the rail <NUM> interposed therebetween are provided in a lower portion of the rail holder 24b. The guide rollers 51a, 51b, 52a, and 52b are made of metal. Each of the guide rollers 51a, 51b, 52a, and 52b has a cylindrical shape whose both ends in the axial direction are open, and a flange <NUM> protruding in a radially outward direction is integrally formed on one end side (upper portion) in the axial direction.

The flanges <NUM> of the guide rollers 51a and 51b provided in a lower portion of the rail holder 24a are arranged on the rail <NUM>, and the flanges <NUM> of the guide rollers 52a and 52b provided in a lower portion of the rail holder 24b are arranged on the rail <NUM>. More specifically, the flange <NUM> of the guide roller 51a overlaps the outer edge of the upper surface of the rail <NUM> (the opposite side of the side facing the rail <NUM>), and the flange <NUM> of the guide roller 51b overlaps the inner edge of the upper surface of the rail <NUM> (the side facing the rail <NUM>). Also, the flange <NUM> of the guide roller 52a overlaps the outer edge of the upper surface of the rail <NUM> (the opposite side of the side facing the rail <NUM>), and the flange <NUM> of the guide roller 52b overlaps the inner edge of the upper surface of the rail <NUM> (the side facing the rail <NUM>). Thus, the entire link mechanism <NUM> is supported by the rails <NUM> and <NUM> via the guide rollers 51a and 51b of the rail holder 24a and the guide rollers 52a and 52b of the rail holder 24b.

In other words, the guide rollers 51a, 51b, 52a, and 52b are support rollers that support the link mechanism <NUM>. More specifically, the guide rollers 51a, 51b, 52a, and 52b are cantilever support rollers that support the link mechanism <NUM> by means of the flanges <NUM> provided on one end side (upper portion) in the axial direction. From another viewpoint, the guide rollers 51a, 51b, 52a, and 52b are flanged rollers having the integrally formed flanges <NUM>.

The four guide rollers 51a, 51b, 52a, and 52b have the same shape, structure, size, and the like. Therefore, the shape and structure of the guide rollers 52a and 52b provided in the rail holder 24b will be clarified by describing the shape and structure of the guide rollers 51a and 51b provided in the rail holder 24a in more detail.

As shown in <FIG>, the roller holding portion 31a of the rail holder 24a is attached to the lower end of the shaft 32a protruding downward from the base member <NUM> so as to be rotatable about the shaft 32a as a rotating shaft. Specifically, the roller holding portion 31a is attached to the lower end of the shaft 32a via a bearing.

<FIG> is a partially enlarged cross-sectional view showing the guide rollers 51a and 51b and the surrounding structures thereof shown in <FIG>. <FIG> is an exploded perspective view showing the guide rollers 51a and 51b and the surrounding structures thereof shown in <FIG>.

As shown in <FIG>, a shaft (roller shaft <NUM>) is provided on one end side of the roller holding portion 31a protruding toward the outer side of the rail <NUM>, and another shaft (roller shaft <NUM>) is provided on the other end side of the roller holding portion 31a protruding toward the inner side of the rail <NUM>. The upper portion of the roller shaft <NUM> is press-fitted into a mounting hole provided in one end of the roller holding portion 31a, and the upper portion of the roller shaft <NUM> is press-fitted into a mounting hole provided in the other end of the roller holding portion 31a.

The guide roller 51a is rotatably attached to the lower portion of the roller shaft <NUM> protruding downward from the roller holding portion 31a. Also, the guide roller 51b is rotatably attached to the lower portion of the roller shaft <NUM> protruding downward from the roller holding portion 31a. Specifically, the lower portion of the roller shaft <NUM> is inserted through the guide roller 51a, and bearings 56a and 56b are interposed between the guide roller 51a and the lower portion of the roller shaft <NUM>. Also, the lower portion of the roller shaft <NUM> is inserted through the guide roller 51b, and bearings 57a and 57b are interposed between the guide roller 51b and the lower portion of the roller shaft <NUM>. Namely, the guide roller 51a is rotatably supported with respect to the roller shaft <NUM> by the two bearings 56a and 56b. Also, the guide roller 51b is rotatably supported with respect to the roller shaft <NUM> by the two bearings 57a and 57b.

The bearings 56a and 56b interposed between the roller shaft <NUM> and the guide roller 51a overlap each other in the axial direction of the roller shaft <NUM>. Specifically, the bearing 56b overlaps the bearing 56a. Namely, the two bearings 56a and 56b overlap in two upper and lower stages. Therefore, in the following description, the bearing 56a is referred to as a "lower bearing 56a" and the bearing 56b is referred to as an "upper bearing 56b" in some cases.

The bearings 57a and 57b interposed between the roller shaft <NUM> and the guide roller 51b overlap in two upper and lower stages in the same manner as the bearings 56a and 56b. Therefore, in the following description, the bearing 57a is referred to as a "lower bearing 57a" and the bearing 57b is referred to as an "upper bearing 57b" in some cases.

As shown in <FIG> and <FIG>, each of the lower bearing 56a and the upper bearing 56b supporting the guide roller 51a is a rolling bearing (ball bearing) including an inner ring <NUM>, an outer ring <NUM> surrounding the inner ring <NUM>, and a plurality of rolling elements (balls) <NUM> arranged between the inner ring <NUM> and the outer ring <NUM>. Each of the lower bearing 56a and the upper bearing 56b further includes a pair of seals <NUM> that close the top and bottom of the gaps between the inner ring <NUM> and the outer ring <NUM>. Each seal <NUM> is annularly formed of a rubber plate, an iron plate, or the like. Each seal <NUM> extends in a radially inward direction from the upper and lower edges of the outer ring <NUM> (toward the inner ring <NUM>) and covers the gap between the inner ring <NUM> and the outer ring <NUM>. A lubricant such as grease is filled in the gap between the inner ring <NUM> and the outer ring <NUM> covered by the seal <NUM>. Understandably, the tip of each seal <NUM> is not in contact with the inner ring <NUM>. Namely, the lower bearing 56a and the upper bearing 56b are sealed bearings, more specifically, non-contact sealed bearings.

Note that the lower bearing 57a and the upper bearing 57b supporting the guide roller 51b are non-contact sealed bearings similar to the lower bearing 56a and the upper bearing 56b described above. Namely, the lower bearing 57a and the upper bearing 57b each include the inner ring <NUM>, the outer ring <NUM>, the rolling elements (balls) <NUM>, and the seal <NUM>, and a lubricant such as grease is filled between the inner ring <NUM> and the outer ring <NUM>.

The guide rollers 51a and 51b are provided with a cover member on at least one of the one end side in the axial direction and the other end side in the axial direction. In this embodiment, cover members are provided on both the one end side and the other end side of the guide rollers 51a and 51b in the axial direction. More specifically, a cover member <NUM> is provided below each of the lower bearing 56a supporting the guide roller 51a and the lower bearing 57a supporting the guide roller 51b. Also, a cover member <NUM> is provided above each of the upper bearing 56b supporting the guide roller 51a and the upper bearing 57b supporting the guide roller 51b. In the following description, the cover member <NUM> is referred to as a "lower cover member <NUM>" and the cover member <NUM> is referred to as an "upper cover member <NUM>" in some cases.

The respective lower cover members <NUM> are formed in a disc shape that closes the bottoms of the guide rollers 51a and 51b. On the other hand, the respective upper cover members <NUM> are formed in an annular shape (flanged ring shape) that surrounds the roller shafts <NUM> and <NUM>.

The lower cover member <NUM> provided below the lower bearing 56a is not fixed to the roller shaft <NUM>, but is fixed to the guide roller 51a. Also, the lower cover member <NUM> provided below the lower bearing 57a is not fixed to the roller shaft <NUM>, but is fixed to the guide roller 51b. A screw thread (male thread 71a) is formed on the outer peripheral surface of each lower cover member <NUM>. A screw thread (female thread <NUM>) that can be coupled with the male thread 71a formed on the lower cover member <NUM> is formed on the inner peripheral surface of each of the guide rollers 51a and 51b. The lower cover member <NUM> is screwed to the guide rollers 51a and 51b by the male thread 71a and the female thread <NUM>.

Note that the means for fixing the lower cover member <NUM> to the guide rollers 51a and 51b is not limited to screw coupling. For example, there are embodiments in which the lower cover member <NUM> is fixed to the guide rollers 51a and 51b by other fixing means such as press-fitting, adhesion, welding, engagement, or the like. Understandably, the lower cover member <NUM> of this embodiment screwed to the guide rollers 51a and 51b is more securely fixed to the guide rollers 51a and 51b as compared with the lower cover members of other embodiments fixed to the guide rollers 51a and 51b by other fixing means such as press-fitting. In addition, the lower cover member <NUM> of this embodiment is more advantageous in terms of manufacturing cost than the lower cover members of other embodiments fixed to the guide rollers 51a and 51b by other fixing means such as press-fitting.

The lower cover member <NUM> of this embodiment screwed to the guide rollers 51a and 51b is detachably attached to the guide rollers 51a and 51b. Therefore, the lower cover member <NUM> can be attached to each of the guide rollers 51a and 51b after the guide rollers 51a and 51b are assembled with the roller shafts <NUM> and <NUM>. Also, if necessary, the lower cover member <NUM> can be detached from the guide rollers 51a and 51b to check the inner state of the guide rollers 51a and 51b.

The upper cover member <NUM> provided above the upper bearing 56b is not fixed to any of the roller shaft <NUM> and the guide roller 51a. Also, the upper cover member <NUM> provided above the upper bearing 57b is not fixed to any of the roller shaft <NUM> and the guide roller 51b. A flange-shaped support portion 72a is integrally formed around the entire peripheral edge of each upper cover member <NUM>. The support portion 72a of the upper cover member <NUM> provided above the upper bearing 56b overlaps the flange <NUM> of the guide roller 51a, but is not fixed to the flange <NUM>. Also, the support portion 72a of the upper cover member <NUM> provided above the upper bearing 57b overlaps the flange <NUM> of the guide roller 51b, but is not fixed to the flange <NUM>. Therefore, each upper cover member <NUM> does not rotate integrally with the guide rollers 51a and 51b, but is rotatable along with the rotation of the guide rollers 51a and 51b. Namely, each upper cover member <NUM> rotates together with the guide rollers 51a and 51b.

The upper cover members <NUM> rotating together with the guide rollers 51a and 51b may be scraped by the contact with the guide rollers 51a and 51b. Also, the upper cover members <NUM> surround the roller shafts <NUM> and <NUM>. Therefore, the upper cover members <NUM> may be scraped by the contact with the roller shafts <NUM> and <NUM>. Thus, in this embodiment, the upper cover member <NUM> made of resin is used in order to avoid the generation of metal powder or the like, which may adversely affect the bearing. Note that there is no fear that the lower covers <NUM> fixed to the guide rollers 51a and 51b generate metal powder. Thus, in this embodiment, the lower cover <NUM> made of metal is used. However, the use of a lower cover member made of resin is not excluded.

The resin material used to form the upper cover member <NUM> is not particularly limited, but fluorine resin can be presented as an example of a resin material capable of providing the upper cover member <NUM> with excellent heat resistance and oil resistance and low contact resistance. Also, the metal material used to form the lower cover member <NUM> is not particularly limited, but carbon steel or SUS (stainless steel) can be presented as an example of an easily processable metal material with excellent heat resistance and oil resistance.

The lower cover member <NUM> arranged below the lower bearing 56a covers the lower side of the gap between the inner ring <NUM> and the outer ring <NUM> of the lower bearing 56a. Also, the lower cover member <NUM> arranged below the lower bearing 57a covers the lower side of the gap between the inner ring <NUM> and the outer ring <NUM> of the lower bearing 57a. Further, the lower cover member <NUM> is arranged outside the lower seal <NUM> of each of the lower bearings 56a and 57a so as to overlap the seal <NUM>. Thereby, the lower side of the gap between the inner ring <NUM> and the outer ring <NUM> of each of the lower bearings 56a and 57a is doubly covered by the seal <NUM> and the lower cover member <NUM>. Therefore, as compared with the case where the gap between the inner ring <NUM> and the outer ring <NUM> is covered only by the seal <NUM>, oil, dust, and others are less likely to enter the gap between the inner ring <NUM> and the outer ring <NUM>.

The upper cover member <NUM> arranged above the upper bearing 56b covers the upper side of the gap between the inner ring <NUM> and the outer ring <NUM> of the upper bearing 56b. Also, the upper cover member <NUM> arranged above the upper bearing 57b covers the upper side of the gap between the inner ring <NUM> and the outer ring <NUM> of the upper bearing 57b. Further, the upper cover member <NUM> is arranged outside the upper seal <NUM> of each of the upper bearings 56b and 57b so as to overlap the seal <NUM>. Thereby, the upper side of the gap between the inner ring <NUM> and the outer ring <NUM> of each of the upper bearings 56b and 57b is doubly covered by the seal <NUM> and the upper cover member <NUM>. Therefore, as compared with the case where the gap between the inner ring <NUM> and the outer ring <NUM> is covered only by the seal <NUM>, oil, dust, and others are less likely to enter the gap between the inner ring <NUM> and the outer ring <NUM>.

As described above, the gap between the inner ring <NUM> and the outer ring <NUM> of each of the lower bearing 56a and the upper bearing 56b supporting the guide roller 51a is doubly covered by the seal and the cover member. Specifically, the lower side of the gap is doubly covered by the seal <NUM> and the lower cover member <NUM>, and the upper side of the gap is doubly covered by another seal <NUM> and the upper cover member <NUM>. Therefore, oil, dust, and others are less likely to enter the gap between the inner ring <NUM> and the outer ring <NUM> of each of the lower bearing 56a and the upper bearing 56b from both the lower side and the upper side thereof, and the life of the lower bearing 56a and the upper bearing 56b (especially lubrication life) can be extended.

Similarly, the gap between the inner ring <NUM> and the outer ring <NUM> of each of the lower bearing 57a and the upper bearing 57b supporting the guide roller 51b is doubly covered by the seal and the cover member. Specifically, the lower side of the gap is doubly covered by the seal <NUM> and the lower cover member <NUM>, and the upper side of the gap is doubly covered by another seal <NUM> and the upper cover member <NUM>. Therefore, oil, dust, and others are less likely to enter the gap between the inner ring <NUM> and the outer ring <NUM> of each of the lower bearing 57a and the upper bearing 57b from both the lower side and the upper side thereof, and the life of the lower bearing 57a and the upper bearing 57b (especially lubrication life) can be extended.

As can be seen from <FIG>, the lower cover member <NUM> is provided in a lower portion of each of the cylindrical guide rollers 51a and 51b, and the upper cover member <NUM> is provided in an upper part thereof. As a result, an annular space is formed around the lower portion of the roller shaft <NUM>, and the lower bearing 56a and the upper bearing 56b are accommodated in the space. Further, an annular space is formed around the lower portion of the roller shaft <NUM>, and the lower bearing 57a and the upper bearing 57b are accommodated in the space. In other words, the guide roller 51a, the lower cover member <NUM>, and the upper cover member <NUM> form an accommodation space around the roller shaft <NUM>, in which the lower bearing 56a and the upper bearing 56b are accommodated. Also, the guide roller 51b, the lower cover member <NUM>, and the upper cover member <NUM> form an accommodation space around the roller shaft <NUM>, in which the lower bearing 57a and the upper bearing 57b are accommodated. Further, the accommodation space may be filled with a lubricant. By filling the spaces in which the lower bearings 56a and 57a and the upper bearings 56b are 57b are accommodated with a lubricant, it is expected that the life of these bearings 56a, 57a, 56b, and 57b can be further extended.

As described above, according to this embodiment, the effect of extending the life of the bearings used in the stretching machine <NUM> can be obtained. This effect is beneficial regardless of the type of film stretched by the stretching machine <NUM>, and is particularly advantageous when the film stretched by the stretching machine <NUM> contains oil.

A resin film used for a separator of a lithium ion secondary battery can be presented as an example of a film containing oil. The separator is arranged between a positive electrode plate and a negative electrode plate of a lithium ion secondary battery, and insulates the positive electrode plate and the negative electrode plate. Therefore, the resin film used for the separator is required to have insulation performance. In addition to the insulation performance, the resin film used for the separator is required to have also the performance of smoothly passing an electrolytic solution, lithium ions, and the like. For this reason, a large number of pores are formed in the resin film used for the separator.

As one method of manufacturing an insulating resin film that satisfies the above requirements, the following method is known. That is, a plasticizer is added to a solvent mixed with a resin material to be a raw material of the insulating resin film (hereinafter referred to as "raw material resin"). This plasticizer is a non-volatile solvent capable of forming a uniform solution at a temperature equal to or higher than the melting point of the raw material resin, and is made of a material that can be extracted and removed after forming the thin film. Oil such as liquid paraffin or paraffin wax is used as such a plasticizer.

When an insulating resin film used for a separator of a lithium ion secondary battery is manufactured by the thin film manufacturing system <NUM> shown in <FIG>, a raw material resin and the solvent containing the plasticizer are kneaded by the extrusion apparatus <NUM>. The raw material resin (kneaded material) kneaded with the solvent becomes the film <NUM> through the T-die <NUM> and the raw sheet cooling apparatus <NUM>. The film <NUM> is supplied to the stretching machine <NUM> and stretched. Thereafter, the plasticizer contained in the film <NUM> is extracted and removed by cleaning process.

The film <NUM> supplied to the stretching machine <NUM> in the above process contains a plasticizer which is oil. Some of the oil contained in the film <NUM> seeps out onto the surface of the film <NUM> during the stretching process. The oil seeped out onto the surface of the film <NUM> adheres to the link mechanism <NUM> and reaches the guide roller through each part of the link mechanism <NUM>.

When the film <NUM> that contains oil is heated in the heat treatment unit <NUM> shown in <FIG>, a large amount of oil seeps out of the film <NUM>. Furthermore, in the heat treatment unit <NUM> having a higher temperature than the surroundings, the oil seeped out from the film <NUM> is vaporized and floats inside the heat treatment unit <NUM>. Therefore, in the manufacturing process described above, oil is likely to adhere to each part of the link mechanism <NUM> particularly when the link mechanism <NUM> passes through the heat treatment unit <NUM>.

Some of the oil adhering to the link mechanism <NUM> reaches the guide roller 51a through, for example, the roller holding portion 31a and the roller shaft <NUM> shown in <FIG>. Further, another part of the oil adhering to the link mechanism <NUM> reaches the guide roller 51b through, for example, the roller holding portion 31a and the roller shaft <NUM> shown in <FIG>. If the oil that has reached the guide roller 51a and the guide roller 51b permeates the inside of these guide rollers 51a and 51b and further permeates the inside of the lower bearings 56a and 57a and the upper bearings 56b and 57b (gap between the inner ring <NUM> and the outer ring <NUM>), the lubricant enclosed in these bearings leaks out, or the leakage of the lubricant is accelerated.

For example, fluorine grease is used as the lubricant enclosed in the bearings such as the lower bearing 56a. However, fluorine grease has low affinity with oils such as liquid paraffin and paraffin wax. For this reason, if the oil (liquid paraffin, paraffin wax, etc.) seeped out from the film <NUM> permeates the inside of the bearings such as the lower bearing 56a, the fluorine grease enclosed in these bearings leaks out, or the leakage of fluorine grease is accelerated. As a result, the life of bearings such as the lower bearing 56a (especially lubrication life) is shortened.

In this embodiment, the cover member for preventing or suppressing oil and dust from entering the bearings such as the lower bearing 56a used in the stretching machine <NUM> is provided. Therefore, even if the oil adhering to the link mechanism <NUM> or the like reaches the guide rollers such as the guide rollers 51a and 51b as described above, the oil is prevented or suppressed from entering the bearings supporting the guide rollers, and the life of the bearings can be extended.

Here, the influence of the oil contained in the film <NUM> on the bearings used in the stretching machine <NUM> has been described by taking the bearings supporting the guide rollers 51a and 51b as an example. However, the oil contained in the film <NUM> may give a similar influence on other bearings used in the stretching machine <NUM> (for example, the bearings supporting the guide rollers 52a and 52b).

Claim 1:
A link mechanism (<NUM>) for a link device (<NUM>) in a stretching machine (<NUM>) configured to stretch a film (<NUM>), the link mechanism (<NUM>) comprising:
a pair of rail holders (24a, 24b);
a base member (<NUM>) bridging the pair of rail holders (24a, 24b);
a link plate (<NUM>, <NUM>) having one end rotatably coupled to one of the pair of rail holders (24a, 24b) and the other end rotatably coupled to another link mechanism (<NUM>); and
a clip (<NUM>) provided at one end of the base member (<NUM>) and configured to grip the film (<NUM>),
wherein each of the rail holders (24a, 24b) includes:
a guide roller (51a, 51b, 52a, 52b) whose both ends in an axial direction are open and which moves along a rail (<NUM>, <NUM>) while rotating;
a shaft (<NUM>, <NUM>) penetrating the guide roller (51a, 51b, 52a, 52b); and
a bearing (56a, 57a, 56b, 57b) interposed between the guide roller (51a, 51b, 52a, 52b) and the shaft (<NUM>, <NUM>) and rotatably supporting the guide roller (51a, 51b, 52a, 52b),
wherein a cover member (<NUM>, <NUM>) that covers the bearing (56a, 57a, 56b, 57b) is provided on at least one of one end side of the guide roller (51a, 51b, 52a, 52b) in the axial direction and the other end side of the guide roller (51a, 51b, 52a, 52b) in the axial direction and
wherein the bearing (56a, 57a, 56b, 57b) includes an inner ring (<NUM>), an outer ring (<NUM>), a rolling element (<NUM>), arranged between the inner ring (<NUM>) and the outer ring (<NUM>), a seal (<NUM>) configured to cover a gap between the inner ring (<NUM>) and the outer ring (<NUM>), a lubricant being filled in the gap,
wherein the cover member (<NUM>, <NUM>) is arranged outside the seal (<NUM>) so as to overlap the seal (<NUM>), and
the gap of the bearing (56a, 57a, 56b, 57b) is doubly covered by the seal (<NUM>) and the cover member (<NUM>, <NUM>).