JP3922621B2 - Plastic pallet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a synthetic resin pallet for forklifts used for storing and transporting luggage, and more particularly to a synthetic resin pallet having a good resin flow during molding.
[0002]
[Prior art]
Conventionally, synthetic resin pallets are molded by an injection molding machine using a mold, but normally used pallets are large molded products such as 1000mm x 1000mm, 1100mm x 1400mm, so usually four-point gates Is injection molded. The reason why the multi-point gate system with a large number of gates is used is to ensure the fluidity of the resin during injection molding, to complete the filling and solidification in a short time, and to increase the productivity. This is because the difference in the foaming density of each part increases as the resin flow distance becomes longer than the gate part.
[0003]
That is, in a large molded product such as a pallet, the resin filling speed is increased by a multi-point gate method to prevent the occurrence of a weld portion. However, even if measures are taken to improve the fluidity of the resin as a multi-point gate system, the occurrence of welds cannot be completely prevented. In view of this, a pallet has been proposed in which a single gate portion is provided at substantially the center of the pallet, and runner ribs that are continuous from the gate portion toward the tip portions of the four corners are provided (for example, JP-A-10-316134). Publication).
[0004]
[Problems to be solved by the invention]
Providing runner ribs from the gate portion toward the tip of the four corners improves the fluidity of the resin and increases the filling speed, so that the occurrence of a weld portion can be prevented. However, if the runner ribs are enlarged, cooling time is required and shrinkage becomes uneven, so there is a limit to increasing the runner ribs.
[0005]
Therefore, the inventor provides a synthetic resin pallet that is further improved to secure the fluidity of the resin at the time of injection molding and to improve the productivity by shortening the cooling time and has a good surface condition. Is.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows. That is, the synthetic resin pallet according to the present invention is a synthetic resin pallet in which an upper deck board and a lower deck board are connected via a support column, and a reinforcing rib is provided on the lower surface of the top plate of the upper deck boat. The gate portion of one point is provided in the substantially central portion, and the thickness of the top plate between the pair of diagonal ribs substantially parallel from the gate portion to the tip portions of the four corners and the pair of diagonal ribs is changed to the other portions. By forming the resin flow path thicker than the wall thickness of the top plate, a resin flow path having a substantially U-shaped cross section is provided, and the diagonal rib is the same as the reinforcing rib in the fork insertion hole at the portion facing the fork insertion hole. It is formed at a height, and a portion in the support column is formed at the same height as the reinforcing rib in the support column. It is preferable that the thickness of the top plate between the pair of diagonal ribs is 150 to 200% of the thickness of the top plate of the other part. In addition, it is preferable that the thickness of the top plate in a certain range centering on the gate portion is formed to be thicker than the thickness of the top plate in other portions.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the illustrated embodiment will be described in detail. The illustrated synthetic resin pallet 10 is formed by connecting an upper deck board 11 and a lower deck board 13 with support columns 15 at both ends and an intermediate support plate 17 provided between them. This is a two-way pallet with a fork insertion hole 19 formed by a space surrounded by the support column 15 and the intermediate support 17.
[0008]
The pallet 10 is divided in a horizontal direction by a dividing line 20 at a substantially central portion of each support column, and is divided into an upper part 21 having an upper deck board and a lower part 23 having a lower deck board in advance. The upper part 21 is composed of the upper deck board 11 and the column parts 15a and 17a, and the lower part 23 is composed of the lower deck board 13 and the column parts 15b and 17b. The divided and molded upper part 21 and lower part 23 can then be integrally formed by abutting and welding the end surfaces of the respective support portions.
[0009]
The column portions 15a and 17a and the column portions 15b and 17b are hollow structures, and a space surrounded by the upper deck board 11 and the lower deck board 13 serves as a fork insertion hole 19. As the synthetic resin for molding the pallet, a foamed resin can be used. For example, polystyrene, polyethylene, polypropylene, vinyl chloride, ABS resin, or the like can be used.
[0010]
Further, the configuration of the upper deck board 11 will be described. The upper deck board 11 includes a top plate 25 and reinforcing ribs 27 and 29 provided vertically and horizontally on the lower surface of the top plate 25. The reinforcing rib 27 is provided so as to face the fork insertion hole 19, and the reinforcing rib 29 is provided in the support columns 15 and 17. The overall height of the upper deck board 11 is determined by the height dimension of the reinforcing rib 27. A through hole 30 is formed at an appropriate position of the top plate 25 in a portion surrounded by the reinforcing rib 29 provided in the support columns 15a and 17a.
[0011]
A feature of the present invention is that a one-point gate system is used, and resin flow paths are provided from the gate portion toward the four corners of the deck board to ensure the fluidity of the resin during injection molding. That is, the gate portion 31 is substantially at the center of the top plate 25 and is provided with resin flow paths 33 from the gate portion 31 toward the four corners.
[0012]
The resin flow path 33 is provided with substantially parallel diagonal ribs 35, 35 extending from the gate portion 31 to the four corners on the lower surface of the top plate, and the thickness of the top plate between the diagonal ribs 35, 35 is set to another portion. The cross section is substantially U-shaped by forming it thicker than the top plate. As shown in FIG. 3, when the thickness of the top plate in the resin flow path 33 is T1, and the thickness of the top plate of the other part is T2, T1> T2, and for example, if T2 is 2 mm, T1 is preferably 3 to 4 mm.
[0013]
The resin flow path 33 feeds the resin that has passed through the gate to the tip of the four corners at the injected speed, and then facilitates the flow of the flowing resin so as to fill the cavity by the expansion force of the resin itself, It is formed to prevent.
[0014]
By forming the diagonal ribs 35 and 35 in parallel at regular intervals, the flow of the resin from the gate portion 31 to the four corners is combined with the fact that the top plate between the diagonal ribs is formed thick. In addition to ensuring the properties, the resin easily flows to the connected reinforcing ribs 27 and 29. Therefore, the diagonal ribs 35 a of the diagonal ribs 35, 35 facing the fork insertion hole are formed at substantially the same height as the reinforcing ribs 27, and the diagonal ribs in the support columns 15, 17 are formed. 35 b is formed at substantially the same height as the reinforcing rib 29.
[0015]
The resin flow path 33 is preferably a straight line. The resin flow path 33 facilitates the flow of the resin so that it can reach the four corners farthest from the gate portion 31 in substantially the same time as the other portions. Will be reinforced.
[0016]
In addition, in order to ensure the fluidity of the resin, the thickness of a certain range with the gate portion 31 as the center, for example, the thickness of the top plate within the range of the width of the intermediate strut portion 17 is made larger than the top plate of other portions. Also, it is preferable to form a thick film having a thickness of 3 to 4 mm, for example, the same as the thickness of the resin flow path 33. In this way, by increasing the thickness of the periphery around the gate portion 31, the resin flow can be further improved.
[0017]
Further, the diagonal ribs 35 are preferably connected to a circular rib 37 provided on the lower surface of the gate portion 31. The circular ribs 37 improve the resin flow to the diagonal ribs 35. The circular rib 37 is preferably substantially the same as the height of the diagonal ribs 35, 35, but may be omitted as appropriate.
[0018]
The reinforcing ribs 27 and 29 provided on the lower surface of the top plate 25 are not limited to grid-like ribs parallel to the end face of the pallet, but may be ribs provided obliquely on the end face of the pallet, or a combination thereof. A rib may be sufficient. Moreover, although the two-way pallet has been described in the above embodiment, the present invention can also be applied to a four-way pallet.
[0019]
【The invention's effect】
As described above, according to the synthetic resin pallet according to the present invention, the one-point gate portion is provided in the center portion of the deck board, and the resin flow paths are provided from the gate portion toward the tip portions of the four corners. The fluidity of the resin is ensured and the occurrence of welds can be prevented. In the foam molding, since the resin flow is uniform, a uniform foamed state can be obtained at a low density.
[Brief description of the drawings]
FIG. 1 is a front view showing an example of a pallet according to the present invention.
2 is a plan view of the pallet, and the left half is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along line BB in FIG.
4 is a cross-sectional view taken along line CC in FIG. 2. FIG.
FIG. 5 is a cross-sectional view taken along line DD in FIG.
[Explanation of symbols]
10: Synthetic resin pallet 11: Upper deck board 13: Lower deck board 15: End strut 17: Intermediate strut 19: Fork insertion hole 20: Split line 21: Upper part 23: Lower part 25: Top plate 27 : Reinforcing rib 29 facing the fork insertion hole: Reinforcing rib 30 in the column part: Through hole 31: Gate part 33: Resin flow path 35: Diagonal rib 37: Circular rib

Claims (3)

In the synthetic resin pallet made by connecting the upper deck board and the lower deck board via a support column, a reinforcing rib is provided on the lower surface of the top plate of the upper deck boat, and a gate part is provided at a substantially central portion. The thickness of the top plate between the pair of diagonal ribs extending from the gate portion toward the tip of the four corners and the pair of diagonal ribs is made thicker than the thickness of the top plate of the other portion. The diagonal rib is formed with a portion facing the fork insertion hole at the same height as the reinforcing rib in the fork insertion hole, and the portion in the column part is a column. A synthetic resin pallet formed at the same height as the reinforcing ribs in the section.   2. The synthetic resin pallet according to claim 1, wherein the thickness of the top plate between the pair of diagonal ribs is 150 to 200% of the thickness of the top plate of the other part. .   The synthetic resin pallet according to claim 1 or 2, wherein a thickness of the top plate in a certain range centering on the gate portion is formed to be thicker than the thickness of the top plate of other portions.

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