Patent Application
20210245417
The present invention relates to a stretching and bending mechanism for stretching and bending a resin sheet material, a resin molding device using the same, a stretching and bending method for stretching and bending a resin sheet material, and a resin molding method using the same.
Conventionally, as a method of forming a skin of an instrument panel of an automobile by molding a resin sheet material, there is known a method in which, after heating a resin sheet material, the resin sheet material is stretched, and bonded to a base material of the instrument panel while performing vacuum forming (see, for example, Patent Literature 1).
According to the method of Patent Literature 1, the resin sheet material is held by a skin clamp device, and heated and stretched. Then, a vacuum suction mold on the base material side on which the base material of the instrument panel is mounted, is raised to a predetermined position with respect to the resin sheet material inclined at a predetermined inclination angle with respect to the horizontal plane, and thereby a portion of the base material is covered with a portion of the resin sheet material.
Next, by lowering a vacuum suction mold on the skin side and pressing the remaining portions of the resin sheet material against the base material, the remaining portions of the base material are covered with the remaining portions of the resin sheet material. Thereafter, by performing clamping and applying suction from the vacuum suction mold on the skin side, a predetermined surface shape is molded in the resin sheet material.
After stopping the suction, when the resin sheet material is sucked up through a ventilation section of the base material from the vacuum suction mold on the base material side, the resin sheet material is bonded to the base material through an adhesive on the back surface thereof. In this way, the skin made of the resin sheet material is formed on the surface of the base material.
Patent Literature 1: Japanese Patent No. 5617796
However, according to the above-described conventional technique, when the resin sheet material held by the skin clamp device is heated, drawdown that is sagging down of the softened resin sheet material occurs. In molding of the resin sheet material, the drawdown causes wrinkles and tears in a formed part of the resin sheet material.
Further, according to the above conventional technique, when the resin sheet material is pressed against the base material of the instrument panel by the vacuum suction mold on the base material side and the vacuum suction mold on the skin side for covering, the resin sheet material is first brought into contact with a portion of the base material, and then portions away therefrom are sequentially pressed against the base material or the vacuum suction mold on the skin side.
At this time, with respect to the portion of the resin sheet material which has been brought into contact with and secured to the base material first, the portions successively away therefrom are sequentially secured to the base material while being stretched. This results in unevenness in the thickness of the resin sheet material and causes of deterioration of the quality of the instrument panel.
In view of the conventional technical problem, it is an object of the present invention to provide a stretching and bending mechanism, a resin molding device, a stretching and bending method, and a resin molding method capable of preventing drawdown of a resin sheet material as much as possible, and capable of preventing unevenness in the thickness of the resin sheet material as much as possible.
A stretching and bending mechanism for stretching and bending a resin sheet material, the stretching and bending mechanism comprising:
a plurality of transverse clamps configured to hold both ends of the resin sheet material in a longitudinal direction;
a plurality of longitudinal clamps configured to hold both ends of the resin sheet material in a transverse direction;
two transverse guides each configured to support the plurality of transverse clamps at the both ends in the longitudinal direction, and to bend in a same direction at a center;
two longitudinal guides each configured to support the plurality of longitudinal clamps at both ends in the transverse direction capable of moving the longitudinal clamps in the longitudinal direction of the resin sheet material;
a motor which moves the transverse guides in the longitudinal direction of the resin sheet material;
a first and second fixed clamps, which constitute the transverse clamps, configured to fix the ends of the resin sheet material in the longitudinal direction, at both sides of the center in the transverse direction at each of the ends in the longitudinal direction; and
a bending guide configured to guide at least one of the longitudinal guides to move toward the center side in the transverse direction as the transverse guides bend;
wherein the transverse guides are bent between the first and second fixed clamps.
According to the present invention, by gripping both ends of the resin sheet material in a longitudinal direction by transverse clamps and moving the transverse clamps by a motor in the longitudinal direction of the sheet material, the resin sheet material can be stretched in the longitudinal direction. After this, while fixing the ends of the resin sheet material in the longitudinal direction, at both sides of the center in the transverse direction by a first and second fixed clamps, which constitute the transverse clamps, each transvers guides are bent, thereby enabling to bent the resin sheet material along the longitudinal direction.
At such time, when the resin sheet material to be bent is a heated material, it is possible to prevent drawdown of the resin sheet material at the time of heating by performing the stretching of the resin sheet material by moving the transverse guides before the heating of the resin sheet material or along with the heating.
Moreover, when bending the transverse guides between the first and second fixed clamps, since at least one of the longitudinal guides move toward the center side in the transverse direction being guided by the bending guide, the resin sheet material would not be stretched in the transverse direction at the time of bending.
According to the present invention, the stretching and bending mechanism may further comprising a frame body configured to support the transverse guides, the longitudinal guides, and the bending guide. In such case, a drive cylinder configured to push up the transverse guides from the frame body may be provided.
According to this configuration, it is able to bend the transverse guides between the first and second fixed clamps by pushing up the transverse guides from the frame body by the drive cylinder.
A resin molding device using the stretching and bending mechanism according to above, the resin molding device comprising:
a heating unit which heats and softens the resin sheet material when the stretching and bending mechanism holding the resin sheet material passes through the heating unit; and
a resin molding unit which forms the resin sheet material, which is stretched in the longitudinal direction and bent along the longitudinal direction by the stretching and bending mechanism so as to approximate a shape of a mold or a base material, by bringing the resin sheet material in close contact with the mold or the base material and vacuum forming or pressure forming.
According to the resin molding device of the present invention, the resin sheet material stretched in the longitudinal direction by the stretching and bending mechanism and bent so as to approximate the shape of the mold or the base material is brought into close contact with the mold or the base material for vacuum forming or pressure forming. Therefore, compared to the case of forming a planar resin sheet material while pushing it against a mold or a base material, it is possible to avoid unevenness in thickness of the resin sheet material when forming.
A stretching and bending method for stretching and bending a resin sheet material of the present invention, comprising:
a holding step of gripping each of both ends of the resin sheet material in a longitudinal direction and a transverse direction respectively by a plurality of transverse clamps supported by transverse guides capable of bending at a center and by a plurality of longitudinal clamps supported by longitudinal guides so as to be capable of moving in the longitudinal direction of the resin sheet material;
a stretching step of stretching the resin sheet material in the longitudinal direction by moving the transverse guides to the longitudinal direction of the resin sheet material;
and a bending step of, after the stretching step, while maintaining a fixed state of the resin sheet material in the transverse direction by a first and second fixed clamps, the first and second fixed clamps being clamps among the plurality of transverse clamps configured to fix both sides of a center of the resin sheet material in the transverse direction at each of both ends of the resin sheet material in the longitudinal direction, bending the resin sheet material along the longitudinal direction by bending the transverse guides between the first and second fixed clamps,
wherein in the bending step, when bending the transverse guides, at least one of the longitudinal guides is guided to move toward the center side in the transverse direction as the transverse guides bend.
According to the stretching and bending method of the present invention, when the heated resin sheet material is bent in the bending step, by stretching the resin sheet material in the longitudinal direction in the stretching step before heating the resin sheet material, it is possible to prevent drawdown of the resin sheet material by the heating.
Moreover, in the bending step, when bending the transverse guides while maintaining the fixing by the first and second fixed clamps in the transverse direction, since at least one of the longitudinal guides move toward the center side in the transverse direction along with the bending, the resin sheet material would not be stretched in the transverse direction at the time of bending.
In such case, in the bending step, the longitudinal guide is guided by pushing up the transverse guides from a body frame which supports the transverse guides and the longitudinal guides movably.
Accordingly, by pushing up the transverse guides from the frame body, it is able to bend the transverse guides while preventing the resin sheet material from being stretched in the transverse direction.
A resin molding method using the stretching and bending method according to the present invention, comprising:
a heating step of heating the resin sheet material stretched in the stretching step, before the stretching step of the stretching and bending method;
an approximating step of approximating the resin sheet material to a shape of a mold or a base material by bending the resin sheet material in the longitudinal direction in the bending step of the stretching and bending method; and
a resin molding step of, after the approximating step, bringing the resin sheet material in close contact with the mold or the base material and performing vacuum forming or pressure forming.
According to the resin molding method of the present invention, the resin sheet material is approximated to a shape of the mold or the base material in the approximating step, and then brought into close contact with the mold or the bases material for vacuum forming or pressure forming. Therefore, compared to the case of forming a planar resin sheet material while pushing it against a mold or a base material, it is possible to avoid unevenness in thickness of the resin sheet material when forming when the resin sheet material is brought into close contact with the mold or the base material.
The following will describe an embodiment of the present invention with reference to the drawings. A resin molding device of this embodiment has a function of forming a resin sheet material and attaching the resin sheet material to a base material of an instrument panel of an automobile as a skin.
As shown in
In the resin molding unit 6, the formed resin sheet material 2 is attached to a base material 28 of the instrument panel as a skin. The stretching and bending mechanism 3 is sequentially moved to the heating unit 5 and the resin molding unit 6 while holding the resin sheet material 2 supplied by the sheet supply unit 4, and is moved back to the sheet supply unit 4 after completing the process in the resin molding unit 6.
As the resin sheet material 2, it is possible to use a material suitable for the skin of the instrument panel, for example, one obtained by bonding a foamed layer of polypropylene foam to a thin film of thermoplastic olefin. The resin sheet material 2 has a rectangular shape corresponding to the skin of the instrument panel.
The resin sheet material 2 is obtained by cutting a resin sheet raw material rolled while being pulled in the winding direction for each longitudinal dimension of the resin sheet material 2 and cutting it at the center in a transverse direction of the resin sheet raw material. Thus, the resin sheet material 2 has already been stretched in the longitudinal direction when the resin sheet raw material is rolled. In other words, an apparatus for rolling the resin sheet raw material while pulling in the winding direction and an apparatus for cutting the resin sheet raw material function as a unit which obtains the resin sheet material 2 in a state of being stretched in the longitudinal direction.
The sheet supply unit 4 includes a sheet delivery mechanism 7 which grips one sheet of the resin sheet material 2 stacked in a lower section of the sheet supply unit 4, and delivers the sheet to the stretching and bending mechanism 3. The stretching and bending mechanism 3 has a substantially rectangular shape, and has a symmetrical structure about the YZ-plane when a direction along the longitudinal direction is the X-axis direction, a direction along the transverse direction is the Y-axis direction, and X-, Y- and Z-axes are defined as shown in
As shown in
A gripping unit which grips a peripheral portion of the resin sheet material 2 is constituted by the first to third clamps 9, 10, 11. The frame body 8 includes a side member 12a on the negative X-axis side and a side member 12b, not shown, on the positive X-axis side parallel to the Y-axis, and a side member 12c on the negative Y-axis side and a side member 12d on the positive Y-axis side parallel to the X-axis.
A plurality of first clamps 9 on the negative X-axis side which grip one of the ends in the longitudinal direction of the resin sheet material 2 are supported to be movable in parallel with the Y-axis by a first guide 13 on the negative X-axis side provided parallel to the Y-axis. A plurality of first clamps 9 on the positive X-axis side which grip the other end in the longitudinal direction of the resin sheet material 2 are supported in the same manner by a similar first guide 13 on the positive X-axis side.
The second clamps 10 are supported to be movable in parallel with the X-axis by a second guide 14 provided parallel to the X-axis, and are opened and closed by turning a second opening and closing shaft 10a in one direction and the other direction. The third clamps 11 are supported to be movable in parallel with the X-axis by a third guide 15 provided parallel to the X-axis, and are opened and closed by turning a third opening and closing shaft 11a in one direction and the other direction.
The end on the negative Y-axis side of each first guide 13 is supported by the second guide 14 as the longitudinal guide to be freely movable in the X-axis direction, and the end on the positive Y-axis side is supported by the third guide 15 as the longitudinal guide to be freely movable in the X-axis direction.
The second guide 14 is fixed to the upper surface of the side member 12c of the frame body 8. On each of the side members 12a and 12b (not shown) of the frame body 8, a fourth guide 16 as the bending guide is provided from a position, which is slightly off-center to the side member 12d, toward the end on the side member 12d side. Both ends of the third guide 15 are supported by the fourth guides 16 of the side members 12a and 12b, respectively, so as to be freely movable in the Y-axis direction.
Each of the first guides 13 is configured to be freely extendable and retractable between substantially the length in the transverse direction of the resin sheet material 2 before being stretched as in
The first clamps 9a as a first fixed clamp, which are a half on the side member 12c side of the first clamps 9 on the negative X-axis side, are fixed to each other and configured to be opened and closed by turning a common first opening and closing shaft 17a along the transverse direction of the frame body 8 in one direction or the other direction. The first clamps 9b as a second fixed clamp, which are a half on the side member 12d side of the first clamps 9 on the negative X-axis side, are fixed to each other and configured to be opened and closed in the same manner by a common first opening and closing shaft 17b along the transverse direction of the frame body 8.
The first clamps 9a and 9b are connected to each other so as to be movable on the first guide 13 in a state in which their positions are fixed, and so as not to hinder the above-described bending of the first guide 13. The first clamps 9 on the positive X-axis side (the side member 12b side) (not shown) are also constituted by the similar first clamps 9a (the first fixed clamp) and 9b (the second fixed clamp) and configured to be opened and closed by the first opening and closing shafts 17a and 17b.
The first clamps 9a and 9b on the negative X-axis side are fixed to one ends of two traction rods 18a and 18b, respectively. The traction rods 18a and 18b extend from the one end side to the negative X-axis direction, and have racks 19a and 19b along the X-axis, respectively.
The first clamps 9a and the first clamps 9b are guided by the second guide 14 and the third guide 15 together with the first guide 13 through pinions 20a and 20b engaged with the respective racks 19a and 19b, and driven in the X-axis direction.
The pinions 20a and 20b are mounted on a drive shaft 21 and driven by turning the drive shaft 21 with a motor 21m, and, as shown in
The side member 12c is formed of a thin plate member in the Z-axis direction, and an end thereof on the side intersecting the side member 12a is placed over the side member 12a. A pulling rod 12e extends from the end toward the negative X-axis direction. As shown in
Provided on the negative X-axis side of the third guide 15 are traction rods 24a and 24b whose one ends are guided by the third guide 15 to be freely movable in the X-axis direction. The traction rods 24a and 24b extend in the positive Y-axis direction and have racks 23a and 23b, respectively, extending in the Y-axis direction.
The other ends of the traction rods 24a and 24b are supported by recesses 35a and 35b provided on the side member 12d so as to be movable in the X-axis direction and the Y-axis direction, respectively. The end of the traction rod 24a on the side guided by the third guide 15 is connected to the end of the first guide 13 so that the traction rod 24a moves together with the first guide 13 in the X-axis direction.
Provided on the negative X-axis side of the side member 12d is a drive shaft 26 having two pinions 25a and 25b engaged with the racks 23a and 23b of the traction rods 24a and 24b, respectively. Provided on the side member 12d is a motor 26m for turning the drive shaft 26 and moving the third guide 15 in the Y-axis direction through the pinions 25a and 25b and the traction rods 24a and 24b. The two pinions 25a and 25b are configured to move in the X-axis direction as the traction rods 24a and 24b move in the X-axis direction.
As described above, the stretching and bending mechanism 3 has a symmetrical structure about the YZ-plane, and the above-described respective elements in
As shown in
The resin molding unit 6 includes: a lower die 29 on which the base material 28 of the instrument panel is mounted, a first elevating mechanism 30 which raises and lowers the stretching and bending mechanism 3 moved in the negative X-axis direction from the heating unit 5; an upper die 31 for vacuum forming the resin sheet material 2 held by the stretching and bending mechanism 3; and a second elevating mechanism 32 which raises and lowers the upper die 31. As shown in
Note that the positive X-axis direction of the stretching and bending mechanism 3 in
In this configuration, when forming a single sheet of resin sheet material 2 and attaching the resin sheet material 2 as a skin to the base material 28 of the instrument panel, first, a holding step (gripping step) of holding the resin sheet material 2 by gripping the ends in the longitudinal direction of the resin sheet material 2 and the ends in the transverse direction thereof is performed.
Specifically, in the sheet supply unit 4, the topmost sheet of the resin sheet material 2 stocked in the lower section of the sheet supply unit 4 is gripped by the sheet delivery mechanism 7, delivered to the stretching and bending mechanism 3, and gripped by the stretching and bending mechanism 3. This resin sheet material 2 is in a state of being stretched in the longitudinal direction. Precisely, as described above, the resin sheet material 2 is obtained by cutting the resin sheet raw material so that the longitudinal direction of the resin sheet material 2 coincides with the longitudinal direction of the resin sheet raw material rolled while being pulled in the winding direction.
When delivering the resin sheet material 2 from the sheet delivery mechanism 7 to the stretching and bending mechanism 3, in the stretching and bending mechanism 3, the first guides 13, the third guide 15, the first clamps 9, the second clamps 10, the third clamps 11, etc. are driven in conjunction with the sheet delivery mechanism 7, and the delivery of the resin sheet material 2 is carried out smoothly.
Next, a heating step is started. In the heating step, the stretching and bending mechanism 3 is moved from the sheet supply unit 4 to the heating unit 5, and the resin sheet material 2 gripped by the stretching and bending mechanism 3 is heated and softened by the heater 27.
In the heating unit 5, when the resin sheet material 2 reaches a predetermined softening temperature and softens, a stretching step of stretching the resin sheet material 2 in the longitudinal direction and the transverse direction is performed. Specifically, a first stretching step of stretching the resin sheet material 2 in the longitudinal direction is performed first. At this time, the stretching and bending mechanism 3 functions as a first stretching mechanism.
The first stretching step is carried out by moving the first guides 13 on the X-axis negative side and positive side in the negative and positive X-axis directions, respectively, to the ends of the second guide 14 and the third guide 15 by the motor 21m through the pinions 20a, 20b and the racks 19a, 19b.
Meanwhile, the second clamps 10 and the third clamps 11 gripping the respective ends in the transverse direction of the resin sheet material 2 move on the second guide 14 and the third guide 15, respectively, as the gripped portions move with the stretching of the resin sheet material 2 in the longitudinal direction. Therefore, the mutual distance between the second clamps 10 and the mutual distance between the third clamps 11 are slightly increased.
Each of the traction rods 24a and 24b also moves into the direction of the corresponding end of the third guide 15 along each first guide 13.
Next, a second stretching step of stretching the resin sheet material 2 in the transverse direction is performed. At this time, the stretching and bending mechanism 3 functions as a second stretching mechanism. The stretching in the second stretching step is carried out by moving the third guide 15 to the vicinity of the side member 12d by the motor 26m through the pinions 25a, 25b and the racks 23a, 23b. Thus, the resin sheet material 2 changes from the state before being stretched in the transverse direction in
Along with this stretching in the transverse direction, the respective first clamps 9 gripping both ends in the longitudinal direction of the resin sheet material 2 move according to the gripped positions as the gripped positions move in the transverse direction. Therefore, during the change from the state shown in
The central portion that continues to be gripped by each of the first clamps 9 is a portion which corresponds to a formed part of the resin sheet material 2 in the transverse direction. The formed part is a portion of the resin sheet material 2 which is formed and used as the skin of the instrument panel. Thus, the stretching of the resin sheet material 2 in the transverse direction is carried out only for the portions on both sides of the formed part in the transverse direction, and stretching is limited as much as possible for the formed part.
When the stretching step is completed in such a manner, next, a bending step is performed to bend the resin sheet material 2 into a shape suitable for the base material of the instrument panel. The bending step is carried out while the resin sheet material 2 has a temperature equal to or higher than a predetermined softening temperature.
As shown in
Consequently, as shown in
Next, clamping is performed by lowering the stretching and bending mechanism 3 by the first elevating mechanism 30 with respect to the lower die 29 on which the base material 28 is mounted and lowering the upper die 31 by the second elevating mechanism 32 so that the upper die 31 reaches the lower die 29 at substantially the same time as the resin sheet material 2 reaches the base material 28. Consequently, the resin sheet material 2 adheres closely to the base material 28.
At this time, as shown in
After clamping, vacuum forming of the resin sheet material 2 is carried out by applying a vacuum suction from the upper die 31 side to perform a molding step of forming embossment, etc. on the surface of the resin sheet material 2. Thereafter, a vacuum suction is applied from the lower die 29 side to stick the back surface of the resin sheet material 2 to the base material 28, whereby the resin sheet material 2 is bonded to the base material 28 with a thermo-fusible adhesive applied in advance to the back surface.
Thereafter, the upper die 31 is raised and opened, a joined product produced by bonding the resin sheet material 2 and the base material 28 together is removed, and an unneeded part of the resin sheet material 2 is cut off, whereby an instrument panel constituted by the base material 28 and the skin is obtained.
According to this embodiment, by subjecting the resin sheet material 2 stretched in the longitudinal direction beforehand to the heating step, it is possible to avoid as much as possible drawdown from being caused in the resin sheet material 2 in the heating step and to prevent wrinkles and tears of the resin sheet material 2 due to drawdown.
Moreover, in the second stretching step, since the ends in the transverse direction of the resin sheet material 2 are pulled while securing ends in the longitudinal direction of the resin sheet material 2 corresponding to the formed part of the resin sheet material 2 with the first clamps 9, it is possible to stretch only both sides of the formed part in the transverse direction without much stretching the formed part of the resin sheet material 2.
Therefore, while ensuring a desired size of the resin sheet material 2 by the stretching step, an increase in the stretch ratio in the transverse direction of the formed part of the resin sheet material 2 is reduced, and unevenness in the thickness of the formed part is decreased. Consequently, it is possible to improve the quality of molding of the resin sheet material 2.
Furthermore, since the resin sheet material 2 stretched in the stretching step is bent along the base material 28 of the instrument panel in the bending step, it is possible to approximate the timings in which the resin sheet material 2 comes into contact with the upper die 31 and the base material 28 when pressing the resin sheet material 2 against the upper die 31 and the base material 28 by clamping. This makes it possible to reduce the quantity of stretching of the resin sheet material 2 at the time of clamping, equalize the thickness of the resin sheet material 2, increase the yield, and improve the productivity of the instrument panel.
The embodiment of the present invention has been described above, but it does not limit the invention. For example, the present invention is not limited to the case where the resin sheet material 2 is formed as a skin to be attached to the base material 28, but can also be applied to the case where the resin sheet material is formed as a single part. The forming of the resin sheet material 2 may also be performed by pressure forming. Moreover, the stretching step and the bending step may also be performed in parallel with the heating step.
After the resin sheet material 2 is softened, the stretching step may be performed in any timing while the stretching and bending mechanism 3 is positioned in the heating unit 5, while the stretching and bending mechanism 3 is being moved from the heating unit 5 to the resin molding unit 6, or after the stretching and bending mechanism 3 is moved to the resin molding unit 6.
In the case where the resin sheet material 2 is obtained by cutting the resin sheet raw material wound into a roll so that its longitudinal direction is the transverse direction of the resin sheet material 2, the resin sheet material 2 obtained by cutting may be stretched in the longitudinal direction by a stretching mechanism like the stretching and bending mechanism 3 before being supplied to the heating unit 5 or the sheet supply unit 4. This stretching mechanism constitutes a unit which obtains a resin sheet material in a state of being stretched in the longitudinal direction similarly to the above-described apparatus which rolls the resin sheet raw material while pulling in the winding direction.
When bending the resin sheet material 2 in the bending step, in addition to bending in one direction as shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-184421 | Sep 2015 | JP | national |
| 2015-184422 | Sep 2015 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15758809 | Mar 2018 | US |
| Child | 17246087 | US |
