Stretching device

Abstract

To provide a biaxial stretching device that can be made compact.SOLUTION: There is provided a biaxial stretching device that has each of stretching mechanisms (10) provided on four sides of a sheet (S) to be processed, each of the stretching mechanisms comprises: a slider box (11) having rails (12) for sliding two sliders (13) provided in parallel on corresponding sides of the stretching mechanism; a chuck (14) provided on each of the two sliders (13) for gripping the corresponding sides of the sheet (S) to be processed; and a drive mechanism (19) for pulling the slider box (11) in a direction perpendicular to the corresponding side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a stretching device such as a biaxial stretching device for stretching a sheet to be processed made of a thermoplastic resin or the like in two directions.

Background Art

[0002] A biaxial stretching device is used when manufacturing a sheet-like product that is thinner than the original sheet to be processed by stretching the sheet to be processed. For example, in the biaxial stretching device described in Patent Document 1, a plurality of arms are attached to each side of a square sheet to be processed by clips (chucks), and the plurality of arms on each side are connected to each other by a pantograph.

[0003] When the arms on the four sides are moved outward in this state, the sheet to be processed is stretched in two directions. As the sheet to be processed is stretched, the distance between the plurality of arms on each side has to increase, but the pantograph provided between the arms on each side absorbs the expansion between the arms on that side and adjusts so that the expansion becomes uniform.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the biaxial stretching device described in Patent Document 1, in the initial state (the state where the sheet to be processed has not been stretched yet), the pantograph is the longest in the direction perpendicular to each side of the sheet to be processed, and when the sheet to be processed is stretched to the maximum, it becomes the longest in the direction parallel to each side. The size of the pantograph is determined by the length of each side of the sheet to be processed at the maximum stretch. Therefore, the greater the stretching ratio of the sheet to be processed, the greater the length of the pantograph in the direction perpendicular to each side in the initial state, and as a result, the entire device becomes larger.

[0006] The problem to be solved by the present invention is to provide a stretching device such as a biaxial stretching device that can be miniaturized.

Means for Solving the Problem

[0007] The biaxial stretching device according to the first aspect of the present invention made to solve the above problems, each of the stretching mechanisms provided on the four sides of the sheet to be processed, a) a slider box having rails for sliding two sliders provided parallel to the corresponding side of the stretching mechanism, b) chucks provided on each of the two sliders for gripping the corresponding side of the sheet to be processed, c) a drive mechanism for pulling the slider box in a direction perpendicular to the corresponding side characterized by comprising.

[0008] In the biaxial stretching device according to the present invention, the stretching mechanism for each side (corresponding side) includes two sliders, and the chucks provided on each slider grip the corresponding side. By pulling the slider boxes of the stretching mechanisms of that side and the side opposite to that side (opposite side) in opposite directions by those drive mechanisms, the sheet to be processed is pulled in the direction connecting those sides (the direction perpendicular to those sides).

[0009] The sheet to be processed is also pulled in the same way by those stretching mechanisms at the two sides adjacent to those sides at the same time. Then, the distance between the two chucks that grip the sheet to be processed at the corresponding side and the opposite side widens. In the biaxial stretching device according to the present invention, the widening of the distance between the two chucks is absorbed by each slider sliding in the slider box.

[0010] According to the biaxial stretching device of the present invention, since the rail, which is a component for adjusting the distance between the chucks, is provided in parallel with the corresponding side of the sheet to be processed, the space occupied by the device in the direction perpendicular to the corresponding side can be suppressed, and thereby the entire device can be miniaturized.

[0011] The biaxial stretching device according to the present invention further includes d) racks of the same pitch fixed to each of the two sliders, e) pinions of the same number of teeth meshing with each of the two racks, f) a synchronization mechanism for rotating the two pinions in synchronization with each other in opposite directions and may be provided.

[0012] According to the biaxial stretching device of this aspect, since the two sliders slide in synchronization in opposite directions, it is possible to prevent the problem that one of the sliders gets stuck and does not move.

[0013] The biaxial stretching device according to the present invention further includes g) a synchronization expansion mechanism for rotating the two pinions of this stretching mechanism in synchronization with the movement of the drive mechanism of the stretching mechanism corresponding to the adjacent side of the sheet to be processed and may be provided.

[0014] According to the biaxial stretching device of this aspect, since the two sliders are driven to slide in opposite directions in synchronization with the driving speed of the adjacent side, that is, the pulling speed of the two adjacent sides, the pulling speeds of the four sides are synchronized, and smooth biaxial stretching processing of the sheet to be processed becomes possible.

[0015] In the biaxial stretching device according to the present invention, in addition to the two sliders with racks in the slider box, a rail for sliding two additional sliders with racks is provided. Further, an additional chuck and an additional pinion for gripping the corresponding side of the sheet to be processed are provided on each of the two additional sliders with racks. The additional racks and additional pinions of the two additional sliders with racks are set to move in opposite directions to each other at speeds corresponding to the gripping positions on the corresponding sides of the two chucks and the two additional chucks.

[0016] According to the biaxial stretching device of this aspect, each side of the sheet to be processed is pulled by four chucks, and the intervals of these four chucks can be expanded synchronously according to the pulling speeds of adjacent sides and the positions of each chuck, so that a smoother biaxial stretching process becomes possible.

[0017] The drive mechanism used in the biaxial stretching device according to the present invention can also be suitably used in stretching devices other than the biaxial stretching device. The stretching device according to the second aspect of the present invention Two rod-shaped gripping members for gripping two opposite sides of a rectangular sheet to be processed along each side, Two first gripping member holders for rotatably holding one end of each of the two gripping members, Two second gripping member holders for rotatably holding the other end of each of the two gripping members, A drive mechanism for pulling the two first gripping member holders and the two second gripping member holders in a direction perpendicular to the two sides at different speeds from each other are provided.

[0018] In the stretching device of the second aspect, after gripping two opposite sides of the rectangular sheet to be processed before stretching by two bar-shaped gripping members along the respective sides, the drive mechanism pulls the two first gripping member holders and the two second gripping member holders in a direction perpendicular to the two sides at different speeds from each other. As a result, the two gripping members rotate with respect to the first gripping member holder and the second gripping member holder by which they are held, respectively, while the one end side and the other end side move away from each other at different speeds. Thereby, the sheet to be processed is unevenly stretched in a direction perpendicular to the two sides such that the stretching ratio (the ratio of the length after stretching to the length before stretching) varies depending on the position between the one end and the other end.

[0019] The state in which the rectangular sheet to be processed is unevenly stretched so that the stretching ratio varies depending on the position corresponds to a transient state that occurs, for example, in a sheet mass production device that stretches the sheet to be processed by holding two opposite sides of the sheet to be processed by clips that move along two rails provided so that the interval gradually increases in some sections as described in Patent Document 2. The stretching device of the second aspect can be suitably used as a testing machine for investigating the state of polymers and the like in the sheet to be processed in such a transient state in such a mass production device.

[0020] In the stretching device according to the second aspect, the speed at which the drive mechanism pulls the two first gripping member holders may be 0. In this case, the two first gripping member holders may be fixed directly or via other members.

[0021] The stretching device of the second aspect can be configured as an option of the stretching device of the first aspect by attaching second gripping member holders to two of the four slider boxes that face each other. In this case, the remaining two slider boxes, the two drive mechanisms that pull them, and the chucks provided on all the slider boxes are not used. Alternatively, the stretching device of the second aspect may be a device separate from the stretching device of the first aspect.

Advantages of the Invention

[0022] According to the present invention, it is possible to miniaturize a stretching device such as a biaxial stretching device.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Mode for Carrying Out the Invention

[0024] Embodiments of the stretching device according to the present invention will be described with reference to FIGS. 1 to 17.

[0025] (1) One embodiment (first embodiment) of the biaxial stretching device according to the first aspect of the present invention As shown in FIGS. 1 and 2, the biaxial stretching device 1 of the first embodiment includes four stretching mechanisms 10 provided corresponding to the four sides of the sheet S to be processed. In FIGS. 1 and 2, these four stretching mechanisms are denoted by reference numerals 10A, 10B, 10C, and 10D in counterclockwise order, but they all have the same configuration.

[0026] The stretching mechanism 10 includes a slider box 11, a chuck 14, a drive mechanism 19, and the like.

[0027] The slider box 11 is a rectangular parallelepiped box, and has a shape in which the direction parallel to the side of the sheet S to be processed corresponding to the extension mechanism 10 (hereinafter referred to as the "corresponding side") (this direction is referred to as the "longitudinal direction") is larger than the width direction and the height direction. As shown in FIG. 3, four rails 12 each composed of a slit parallel to the corresponding side are provided on the upper surface of the slider box 11. These four rails 12 are referred to as a first rail 121, a second rail 122, a third rail 123, and a fourth rail 124 in order from the side closer to the sheet S to be processed. Each rail 12 has the first rail 121 and the second rail 122 having the same length, and the third rail 123 and the fourth rail 124 having the same length and being shorter than the first rail 121 and the second rail 122. The first rail 121 extends from a position near one end in the longitudinal direction to a position closer to the other end than the center in the longitudinal direction. The second rail 122 extends from a position near the other end to a position closer to the one end than the center. The third rail 123 extends from a position closer to the one end than the intermediate position between the one end and the center to a position closer to the other end than the center. The fourth rail 124 extends from a position closer to the other end than the intermediate position between the other end and the center to a position closer to the one end than the center.

[0028] Inside the slider box 11, sliders 13 that slide along each rail 12 are accommodated one by one for each rail 12 (FIG. 3). Hereinafter, the sliders 13 provided on the first rail 121, the second rail 122, the third rail 123, and the fourth rail 124 are referred to as a first slider 131, a second slider 132, a third slider 133, and a fourth slider 134, respectively. Each slider 13 has a flat upper surface flush with the upper surface of the slider box 11, and a rack 15 described later is fixed to the lower surface.

[0029] One chuck 14 is fixed to the upper surface of each slider 13. The chuck 14 is disposed outside the slider box 11. The chucks 14 fixed to the first slider 131, the second slider 132, the third slider 133, and the fourth slider 134 are referred to as a first chuck 141, a second chuck 142, a third chuck 143, and a fourth chuck 144, respectively. Each chuck 14 has a base portion 1491 whose lower surface is fixed to each slider 13, and a gripping portion 1492 that grips the sheet S to be processed. A part of the base portion 1491 protrudes closer to the corresponding side of the sheet S to be processed than the upper surface of the slider box 11, and the gripping portion 1492 is provided at the protruding portion. All of these first chuck 141 to fourth chuck 144 move in the longitudinal direction of the slider box 11 as the first slider 131 to fourth slider 134 slide along the first rail 121 to fourth rail 124.

[0030] Separate from these first chuck 141 to fourth chuck 144, a zero-th chuck 140 is fixed outside the slider box 11 at the longitudinal center of its upper surface. The zero-th chuck 140 is not fixed with a slider 13 or a rack 15 described later, and does not move from the longitudinal center.

[0031] The chucks 14 are arranged in the order of the first chuck 141, the third chuck 143, the zero-th chuck 140, the fourth chuck 144, and the second chuck 142 in sequence from one end in the longitudinal direction, and this order does not change even when each chuck 14 moves in the longitudinal direction.

[0032] A rack 15 is provided on the lower surface (inside the slider box 11) of each slider 13. Hereinafter, with reference to FIG. 4 which is a bottom view showing a state where the upper and lower plates of the slider box 11 are removed and FIG. 5 which is a top view for facilitating understanding of the configurations such as the rack 15 and the pinion 16 described later, an explanation will be given. FIG. 5 shows a state where the 0th chuck 140 is also removed. The racks 15 fixed to the 1st slider 131, 2nd slider 132, 3rd slider 133, and 4th slider 134 are referred to as the 1st rack 151, 2nd rack 152, 3rd rack 153, and 4th rack 154, respectively. Each rack 15 extends in the longitudinal direction of the slider box 11, has gears formed on the lower surface (FIG. 4), and has a flat upper surface (FIG. 5). This flat upper surface is fixed to the lower surface of the slider 13. Each rack 15 is movable in the longitudinal direction. The pitch of the teeth of the gears of each rack 15 is the same.

[0033] Furthermore, inside the slider box 11, a total of 4 pinions 16 that mesh with each rack 15 are provided, one for each. The pinions 16 provided corresponding to the 1st rack 151, 2nd rack 152, 3rd rack 153, and 4th rack 154 are referred to as the 1st pinion 161, 2nd pinion 162, 3rd pinion 163, and 4th pinion 164, respectively. The 1st pinion 161 and the 2nd pinion 162 have the same number of teeth and the same diameter. The 3rd pinion 163 and the 4th pinion 164 have the same number of teeth and the same diameter, but the number of their teeth and the diameter are 1 / 2 of those of the 1st pinion 161 and the 2nd pinion 162.

[0034] The second pinion 162 and the fourth pinion 164 rotate about the main rotation axis 184, and the first pinion 161 and the third pinion 163 rotate about the driven rotation axis 173. The main rotation axis 184 and the driven rotation axis 173 penetrate through the side surface of the slider box 11 opposite to the corresponding side and extend outside the slider box 11. A main gear 171 that rotates about the main rotation axis 184 is provided at a position outside the slider box 11 on the main rotation axis 184. A driven gear 172 that rotates about the driven rotation axis 173 is provided at a position outside the slider box 11 on the driven rotation axis 173. The main gear 171 and the driven gear 172 have the same number of teeth and mesh with each other.

[0035] The main rotation axis 184 is rotated by a rotation mechanism 18 described later. At this time, the driven rotation axis 173 and the driven gear 172 rotate in opposite directions to each other at the same speed (the number of rotations per unit time) as the main rotation axis 184 and the main gear 171. As a result, the first pinion 161 and the second pinion 162 having the same number of teeth rotate in opposite directions to each other at the same speed (as above), and the first rack 151 and the second rack 152 move in opposite directions to each other at the same speed (the linear movement distance per unit time). Also, the third pinion 163 and the fourth pinion 164 having the same number of teeth and having half the number of teeth of the first pinion 161 etc. rotate in opposite directions to each other at the same speed as the first pinion 161 etc., and the third rack 153 and the fourth rack 154 move in opposite directions to each other at half the speed of the first rack 151 etc. As a result, the chucks 14 fixed to each rack 15 move in opposite directions to each other at the same speed for the first chuck 141 and the second chuck 142, and the third chuck 143 and the fourth chuck 144 move in opposite directions to each other at the same speed and at half the speed of the first chuck 141 etc.

[0036] Since the main gear 171 and the driven gear 172 operate as described above, they correspond to the above-mentioned "synchronization mechanism for rotating two pinions in synchronization in opposite directions".

[0037] The main rotating shaft 184 and the driven rotating shaft 173 are located at the same height, and as described above, the third pinion 163 and the fourth pinion 164 have a smaller diameter than the first pinion 161 and the second pinion 162. Therefore, as shown in FIG. 6, the upper ends of the first pinion 161 and the second pinion 162 are higher than the upper ends of the third pinion 163 and the fourth pinion 164. Accordingly, the first rack 151 and the second rack 152 that mesh with these pinions 16 are located at a higher position than the third rack 153 and the fourth rack 154. In order to align the positions of the upper surfaces of the respective sliders 13 with the upper surface of the slider box 11 while corresponding to these height differences, the third slider 133 and the fourth slider 134 having a greater height than the first slider 131 and the second slider 132 are used.

[0038] The rotation mechanism 18 includes a first base 181, a first motor 182 provided on the first base, a first transmission mechanism 183, and the main rotating shaft 184. The first base 181 is connected to the slider box 11 by a connecting rod 196 of the drive mechanism 19 described later. The first base 181 is movable forward and backward in a direction perpendicular to the corresponding side of the sheet S to be processed, and the entire rotation mechanism 18 and the slider box 11 move forward and backward in this direction due to the forward and backward movement of the first base 181. The first transmission mechanism 183 is a mechanism that transmits the rotation of the shaft of the first motor 182 to the main rotating shaft 184, and a known mechanism can be used.

[0039] The drive mechanism 19 includes a second base 191, a second motor 192, a second transmission mechanism 193, a screw shaft 194, a second upper rail 195 on the base, and the connecting rod 196. The second transmission mechanism 193 is a mechanism that transmits the rotation of the shaft of the second motor 192 to the screw shaft 194. The axis of the screw shaft 194 extends in a direction perpendicular to the corresponding side of the sheet S to be processed. The second upper rail 195 on the base is provided on the upper surface of the second base 191 and extends in a direction perpendicular to the corresponding side. A screw member (not shown) that meshes with the screw of the screw shaft 194 is fixed to the first base 181 and is placed on the second upper rail 195 on the base. When the screw shaft 194 rotates, the first base 181 moves forward and backward along the second upper rail 195 in a direction perpendicular to the corresponding side.

[0040] The slider boxes 11 of the stretching mechanisms 10A and 10C have their longitudinal directions parallel to each other and are arranged at the same height. The slider boxes 11 of the stretching mechanisms 10B and 10D have their longitudinal directions substantially parallel to each other and are arranged at the same height. However, when compared with the slider boxes 11 of the stretching mechanisms 10A and 10C, their longitudinal directions are substantially orthogonal and they are arranged at a lower position.

[0041] The slider boxes 11 respectively included in the four stretching mechanisms 10A, 10B, 10C, and 10D, each part provided in the slider box 11, the entire chuck 14, the main gear 171, the driven gear 172, and the driven rotating shaft 173, as well as a part of the main rotating shaft 184 and the connecting rod 196 are housed in one (common) thermostatic chamber 20 (see FIG. 1. The thermostatic chamber 20 is omitted in FIG. 2). Holes through which the main rotating shaft 184 and the connecting rod 196 pass are provided in the side wall of the thermostatic chamber 20. A heater 21 is provided in the thermostatic chamber 20. By being heated by this heater 21, the inside of the thermostatic chamber 20 can be maintained at a temperature at which the sheet S to be processed softens. The upper plate (not shown) of the thermostatic chamber 20 is openable. When attaching the sheet S to be processed to the chuck 14 or when removing the processed sheet S from the chuck 14 after the stretching process, the upper plate is opened for the operation.

[0042] The biaxial stretching device 1 further includes a control unit 25 that controls the rotation of the first motor 182 and the second motor 192 included in each stretching mechanism 10, as well as the output of the heater 21. Regarding the rotation of the first motor 182 and the second motor 192, for example, when focusing on the stretching mechanism 10A, as the second motors 192 of the stretching mechanisms 10B and 10D adjacent to both sides of the stretching mechanism 10A rotate, the speed of the rotation of the first motor 182 of the stretching mechanism 10A and the second motors 192 of the stretching mechanisms 10B and 10D is controlled so that each chuck of the stretching mechanism 10A moves at a speed synchronized with the speed at which the corresponding sides of the stretching mechanism 10A of the sheet S to be processed are stretched. The rotation speeds of the first motor 182 and the second motors 192 of the stretching mechanisms 10B to 10D are controlled in the same manner for each of these stretching mechanisms, that is, the rotation speeds of the first motor 182 of that stretching mechanism and the second motors 192 of the stretching mechanisms adjacent to both sides are controlled. The first motor 182, the second motor 192, and the control unit 25 correspond to the "synchronous expansion mechanism that rotates two pinions of this stretching mechanism in synchronization with the movement of the drive mechanism of the stretching mechanism corresponding to the adjacent sides of the sheet to be processed."

[0043] A method of using the biaxial stretching device 1 of the first embodiment will be described. In the initial state, by rotating the first motor 182, each chuck 14 is arranged so that the adjacent chucks 14 are closest to each other as shown in FIGS. 1 and 7. In this state, the upper plate of the thermostatic chamber 20 is opened, and the four sides of the square sheet S to be processed are gripped by the chucks 14. Then, the upper plate of the thermostatic chamber 20 is closed.

[0044] The control unit 25 controls the temperature by passing a current through the heater 21 and adjusting the magnitude of the current so that the inside of the thermostatic chamber 20 is within a predetermined temperature range in which the sheet S to be processed softens. After the inside of the thermostatic chamber 20 reaches within this temperature range, the control unit 25 moves the slider box 11 toward the side opposite to the corresponding side of the sheet S to be processed by rotating the second motor 192 of each stretching mechanism 10 (the vertical arrow in FIG. 8). At the same time, the control unit 25 rotates the first motor 182 of each stretching mechanism 10. Due to the rotation of this first motor 182, as described above, the first chuck 141 and the second chuck 142 move in opposite directions at the same speed (the horizontal arrow in FIG. 8), and the third chuck 143 and the fourth chuck 144 move in opposite directions at the same speed and at half the speed of the first chuck 141 etc. (the same). Note that the zero-th chuck 140 does not move. Here, the control unit 25 controls the rotation speeds of the first motor 182 and the second motor 192 of each stretching mechanism 10 so that the movement of each chuck 14 synchronizes with the speed at which the corresponding side of the sheet S to be processed is stretched by the adjacent stretching mechanisms 10 on both sides thereof in each stretching mechanism 10.

[0045] By the above operations, the sheet S to be processed is stretched in four directions. FIG. 8 shows a state in which the sheet S to be processed is stretched to about half of the most stretched state, and FIGS. 9 and 10 show the state in which the sheet S to be processed is most stretched. The degree of stretching of the sheet S to be processed (the distance by which the slider box 11 is moved) is arbitrary.

[0046] After the stretching of the sheet S to be processed is completed, the heater 21 is stopped, the upper plate of the thermostatic chamber 20 is opened, and the sheet S to be processed is taken out.

[0047] According to the biaxial stretching device 1 of the first embodiment, since the rail 12, which is a component for adjusting the interval between the chucks 14, is provided parallel to the corresponding side of the sheet S to be processed, the space occupied by the device in the direction perpendicular to the corresponding side can be suppressed, and thereby the entire device can be miniaturized.

[0048] As the entire apparatus can be miniaturized in this way, the volume of the thermostat 20 can also be miniaturized, so that the power consumption of the heater 21 can be suppressed.

[0049] In the examples shown so far, the four sides of the sheet S to be processed are evenly expanded, but they may not be even on the two opposite sides, and the degree of expansion may be changed. For example, after gripping two opposite sides of the four sides of the sheet S to be processed with the chucks 14 of only two opposite ones (for example, the stretching mechanisms 10A and 10C) among the four stretching mechanisms 10, the slider box 11 is moved in a direction perpendicular to the corresponding side of the sheet S to be processed in one or both of these two stretching mechanisms 10, and an operation of moving the chuck 14 only in one of the stretching mechanisms 10 may be performed. In these cases, since the chuck 14 of the stretching mechanism 10 in which the slider box 11 moves does not need to be synchronized with the slider boxes 11 of the remaining two stretching mechanisms 10 (which move simultaneously in all the stretching mechanisms 10 in the previous example but do not move in this example), it can be moved independently of the slider box 11. That is, the slider box 11 and the chuck 14 may be moved simultaneously, or only one of them may be moved first. In any case, finally, as shown in FIG. 11, the sheet S to be processed is stretched into a trapezoidal shape.

[0050] (2) An embodiment of the biaxial stretching apparatus according to the second aspect of the present invention (second embodiment) As shown in Fig. 12, the stretching device 3 of the second embodiment is obtained by adding an additional mechanism 30 as an option to the biaxial stretching device 1 of the first embodiment. The additional mechanism 30 is detachably attached to the upper surfaces of the slider boxes 11 of two opposing stretching mechanisms 10B and 10D among the four stretching mechanisms 10A to 10D of the biaxial stretching device 1. Further, since the slider boxes 11 of the two stretching mechanisms 10A and 10C to which the additional mechanism 30 is not attached are not used in the stretching device 3 of the second embodiment, they are retracted by operating the drive mechanisms 19 provided in these two stretching mechanisms 10A and 10C as shown by the dashed lines in Fig. 12. The chuck 14 provided in the biaxial stretching device 1 is removed from the slider boxes 11 of the stretching mechanisms 10B and 10D to which the additional mechanism 30 is attached (the chucks 14 of the slider boxes 11 of the stretching mechanisms 10A and 10C that are not used may remain attached).

[0051] As shown in the enlarged view of Fig. 13, the additional mechanism 30 includes two gripping members 31, two first gripping member holding portions 32, and two second gripping member holding portions 33.

[0052] The gripping member 31 is a rectangular bar-shaped member in top view, and a clip 311 for gripping the long side of the rectangular workpiece sheet S over a linear range is provided on one side of the long side of the rectangle. The two gripping members 31 are arranged such that the clips 311 face each other. A groove 312 extending in the longitudinal direction is provided on the bottom surface of the gripping member 31.

[0053] The two first gripping member holding portions 32 are members fixed to stand apart from each other on the surface of one (common) plate-shaped member 320 in the present embodiment, and are inserted into holes provided at one end of each of the two gripping members 31 (the end on the stretching mechanism 10C side in this example). Thereby, each of the two first gripping member holding portions 32 rotatably holds the gripping member 31 inserted therethrough.

[0054] The two second gripping member holders 33 are each members fixed so as to stand on the upper surface of a plate-shaped fixture 330 fixed to the upper surface of each of the two opposing slider boxes 11 with screws. At their tips, they have cam followers that rotate about an axis perpendicular to the upper surface of the fixture 330. These two second gripping member holders 33 are inserted into grooves 312 provided in each of the two gripping members 31. At the other end of the gripping member 31 (the end on the stretching mechanism 10A side in this example), a stopper 313 for preventing the detachment of the second rotation shaft 332 from the groove 312 is provided. With these configurations, the second gripping member holder 33 can slide relative to the groove 312 of the gripping member 31, and the gripping member 31 can be rotated in a slid state until it abuts against the stopper 313 (Fig. 14(b)). At that time, since the second gripping member holder 33 has a cam follower, the gripping member 31 can be rotated smoothly. Note that instead of having a cam follower, the second gripping member holder 33 may use a member composed of a pin.

[0055] The control unit 25 controls the operations of the second motors 192 of the stretching mechanisms 10B and 10D and the output of the heater 21. The control of the second motors 192 of the stretching mechanisms 10A and 10C that are not used in the stretching device 3 of the second embodiment and the first motors 182 of each stretching mechanism 10 is unnecessary.

[0056] The operation of the stretching device 3 of the second embodiment will be described. First, the control unit 25 operates the drive mechanisms 19 provided in the stretching mechanisms 10B and 10D to bring the two gripping members 31 closer to a distance slightly closer than the lengths of the two sides of the processed sheet S that are not gripped by the gripping members 31. Subsequently, the two gripping members 31 are slid to appropriate positions in the longitudinal direction (positions where the user can work easily). Then, the user grips two sides of the four sides of the processed sheet S with the clips 311 of different gripping members 31.

[0057] Next, the control unit 25 controls the temperature by passing a current through the heater 21 and adjusting the magnitude of the current so that the inside of the thermostatic chamber 20 is within a predetermined temperature range in which the sheet S to be processed softens. After the inside of the thermostatic chamber 20 reaches within this temperature range, the control unit 25 rotates the second motors 192 of the stretching mechanisms 10B and 10D to move the two slider boxes 11 in opposite directions (directions perpendicular to the two sides of the sheet S to be processed held by the gripping members 31). Then, the two gripping members 31 are pushed by the second gripping member holding portions 33 fixed to the slider boxes 11 via the fixtures 330 and move in opposite directions. As a result, the two gripping members 31 rotate in opposite directions about the first gripping member holding portion 32 and slide while being guided in the grooves 312 until the second gripping member holding portion 33 abuts against the stopper 313. When the second gripping member holding portion 33 abuts against the stopper 313, the two gripping members 31 further rotate in opposite directions about the second gripping member holding portion 33.

[0058] By the above operation, as shown in FIG. 15, the two gripping members 31 move such that the distance between the other ends opens while the distance between the one ends does not change, and are arranged in the shape of the Japanese katakana character "HA". By the movement of the gripping members 31, the sheet S to be processed is stretched in a direction perpendicular to the two sides held by the gripping members 31 as a whole, but the stretching rate is non-uniform, being the largest near the other end and approximately 1 (almost no stretching) near the one end. The shape of the sheet S after stretching is trapezoidal.

[0059] According to the stretching device 3 of the second embodiment, in a sheet mass production device including a uniaxial stretching device or a sequential biaxial stretching device using two rails provided so that the interval gradually expands in a part of the section, a sheet reproducing a transient state can be obtained. By investigating the state of polymers and the like in the sheet thus obtained, the phenomenon occurring in the sheet by the mass production machine can be confirmed.

[0060] (3) Modification The present invention is not limited to the above embodiments, and various modifications are possible.

[0061] For example, in the biaxial stretching device 1 of the first embodiment, as shown in FIG. 16, the 0th chuck 140 may be omitted.

[0062] Also, in the biaxial stretching device 1 of the first embodiment, as shown in FIG. 17, the 3rd chuck 143 and the 4th chuck 144 may be omitted. In that case, the 3rd rail 123, the 4th rail 124, the 3rd slider 133, the 4th slider 134, the 3rd rack 153, the 4th rack 154, the 3rd pinion 163, and the 4th pinion 164 are unnecessary. Alternatively, in the configuration shown in FIG. 17, the 0th chuck 140 may be further omitted.

[0063] In FIGS. 16 and 17, examples of reducing the number of chucks 14 compared to the above embodiment are shown. Conversely, the number of chucks 14 may be increased compared to the first embodiment. In that case, the same number of rails 12, sliders 13, racks 15, and pinions 16 are also increased. Then, the number of teeth of each pinion 16 is set so that each chuck 14 moves in synchronization with the stretching speed of the corresponding side by the stretching mechanism 10 adjacent to the corresponding side of the sheet to be processed. For example, when adding two chucks to both outer sides of the five chucks (the 0th chuck 140 to the 4th chuck 144) shown in the above embodiment, and adding two rails, sliders, racks, and pinions corresponding to those two chucks, and setting the number of teeth of those two pinions to 3 / 2 times that of the 1st pinion 161, a configuration in which a total of seven chucks are provided per slider box can be adopted. The same applies when further increasing the number of chucks (to 9, 11, etc.) or omitting the 0th chuck 140 from them (resulting in a total of 6, 8, 10, etc.).

[0064] If the frictional resistance on the slider 13 generated when moving the rail 12 is made sufficiently small, it is possible to move each chuck 14 in synchronization with the stretching speed of the corresponding side of the sheet to be processed by the stretching mechanism 10 adjacent to the corresponding side of the sheet to be processed, even without using the rack 15, pinion 16, etc. In that case, in the biaxial stretching device 1 of the first embodiment, the rack 15, pinion 16, and rotation mechanism 18 may be omitted.

[0065] The stretching device 3 of the second embodiment is obtained by adding an additional mechanism 30 as an option to the biaxial stretching device 1 of the first embodiment. However, as a device different from the biaxial stretching device 1 of the first embodiment, a device may be used in which gripping members 31, a first gripping member holding portion 32, and a second gripping member holding portion 33 are respectively installed in two drive mechanisms and the gripping members 31 are arranged to face each other.

[0066] In the stretching device 3 of the second embodiment, since the two first gripping member holding portions 32 are fixed to one (common) plate-like member 320, when pulling the sheet to be processed S, it does not move in the pulling direction. Therefore, the sheet to be processed S is hardly stretched near the one end of the gripping member 31. On the other hand, when it is desired to stretch the sheet to be processed S unevenly at different stretching rates near one end and the other end while stretching also near one end of the gripping member, the two first gripping member holding portions may not be fixed to each other, and the two second gripping member holding portions may be pulled by a drive mechanism and the two first gripping member holding portions may be pulled at a pulling speed different from that of the second gripping member holding portion. By thus making the pulling speeds of the first gripping member holding portion and the second gripping member holding portion different, the sheet to be processed is stretched unevenly at different stretching rates near one end and the other end of the gripping member. At that time, the stretching rate near the one end can be adjusted by the pulling speed of the first gripping member holding portion.

Explanation of Reference Numerals

[0067] 1... Biaxial stretching device 10, 10A, 10B, 10C, 10D... Stretching mechanism 11... Slider box 12... Rail 121…First rail 122…Second rail 123…Third rail 124…Fourth rail 13…Slider 131…First slider 132…Second slider 133…Third slider 134…Fourth slider 14…Chuck 140…Zero-th chuck 141…First chuck 142…Second chuck 143…Third chuck 144…Fourth chuck 1491…Base 1492…Gripping part 15…Rack 151…First rack 152…Second rack 153…Third rack 154…Fourth rack 16…Pinion 161…First pinion 162…Second pinion 163…Third pinion 164…Fourth pinion 171…Main gear 172…Driven gear 173…Driven rotating shaft 18…Rotating mechanism 181…First base 182…First motor 183…First transmission mechanism 184…Main rotating shaft 19…Driving mechanism 191…Second base 192…Second motor 193…Second transmission mechanism 194…Screw shaft 195…Upper rail on the second base 196…Connecting rod 20…Constant temperature bath 21…Heater 25…Control unit 3…Extension device 30... Additional mechanism 31... Gripping member 311... Clip 312... Groove 313... Stopper 32... First gripping member 320... Fixture of the first gripping member 33... Second gripping member holding part 330... Fixture of the second gripping member holding part S... Sheet to be processed

Claims

1. Each of the stretching mechanisms provided on the four sides of the sheet to be processed comprises a) a slider box having rails for sliding two sliders provided parallel to the corresponding side of the stretching mechanism, b) chucks provided on each of the two sliders for gripping the corresponding side of the sheet to be processed, c) a drive mechanism for pulling the slider box in a direction perpendicular to the corresponding side A biaxial stretching device characterized by comprising.

2. Furthermore, d) racks of the same pitch fixed to each of the two sliders, e) pinions of the same number of teeth meshing with each of the two racks, f) a synchronization mechanism for synchronously rotating the two pinions in opposite directions to each other The biaxial stretching device according to claim 1, characterized by comprising.

3. Furthermore, g) a synchronization extension mechanism for rotating the two pinions of this stretching mechanism in synchronization with the movement of the drive mechanism of the stretching mechanism corresponding to the adjacent sides of the sheet to be processed The biaxial stretching device according to claim 2, characterized by comprising.

4. In the slider box, rails for sliding two additional sliders with racks are further provided, Additional chucks and additional pinions for gripping the corresponding side of the sheet to be processed are provided on each of the two additional sliders with racks, The additional racks and additional pinions of the two additional sliders with racks are set to move in opposite directions to each other at speeds corresponding to the gripping positions of the two chucks and the two additional chucks on the corresponding side. The biaxial stretching device according to claim 2 or 3, characterized by this.

5. Two rod-shaped gripping members for gripping two opposite sides of a rectangular sheet to be processed along each side, Two first gripping member holders for rotatably holding one end of each of the two gripping members, Two second gripping member holders for rotatably holding the other end of each of the two gripping members, A drive mechanism for pulling the two first gripping member holders and the two second gripping member holders in a direction perpendicular to the two sides at different speeds from each other A stretching device characterized by comprising.

6. The stretching device according to claim 5, characterized in that the speed at which the drive mechanism pulls the two first gripping member holders is 0.

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