JP2003072753A - Spring-structured resin pallet and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin pallet with high impact absorbability, resistance to load and durability. SOLUTION: The pallet comprising a three-dimensional structure includes a contact and interwining assembly of adjacent continuous lines and/or short random loops or curls made of a thermoplastic resin and has gaps of a predetermined bulk density. A high density region H with an increased bulk density is formed at both longitudinal ends of a fork insertion port of a single pallet and approximately at the center to reach both longitudinal and widthwise ends of the fork insertion port. In addition, a flat part M with a bulk density less than that of the high density region is formed on an internal surface of the fork insertion port or a pallet outer peripheral surface including an outer peripheral surface of the fork insertion port.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin pallet having a spring structure and a method of manufacturing the resin pallet. More specifically, it has excellent cushioning impact resistance, load resistance, and durability, and has a long life, is lightweight, and is easy to manufacture. An inexpensive spring structure resin pallet and a manufacturing method thereof.

[0002]

2. Description of the Related Art Pallets used for transshipment or transportation of articles by forklift are lightweight, articles with a large surface friction coefficient are not slippery, and water adhering to the surface is absorbed immediately. Generally, wood is often used for reasons such as the fact that articles do not get wet. This wooden pallet is made up of a plurality of wooden corner blocks arranged in parallel at a predetermined interval and joined together by wooden boards such as nailing or screwing to form a pallet body, and the space surrounded by the square blocks and the wooden boards is forklifted. It is a fork slot.

[0003]

The most popular wooden pallets at present are advantages such as low manufacturing cost and a certain level of strength, but the disadvantages are large weight and moisture. Since it is easy to absorb, it easily corrodes and has a short life. In addition, it is easily soiled at an early stage, which makes it difficult to use in the food industry and the pharmaceutical industry. Further, when the pallets are leaned against each other and loaded in the open air, there is a problem that the lower end of the pallets that absorb and contain a large amount of rain water is quickly corroded.

On the other hand, the plastic pallet has a complicated rib structure in order to reduce the weight, and the upper and lower surfaces of the pallet are separately injection-molded and then the upper and lower surfaces are fusion-bonded to each other, which has a long life and is unlikely to become dirty. It has advantages such as
It is much more expensive than a wooden pallet, and has no durability or impact strength.

That is, the conventional plastic pallet has a rib structure because it is made of a plastic whose specific gravity is heavier than wood, so that it has a rib structure, but since the rib thickness is thin, stress concentration occurs and it has a longer life than a wooden pallet. However, it has a drawback that it may be deformed or cracked during long-term use.

Further, although the steel pallet has a very high strength, it is heavy and corrodes due to rust.

The present invention solves the above-mentioned problems, and unlike the conventional resin pallet, because of the spring structure,
Stress concentration does not occur, it can withstand long-term use, and also in manufacturing, because the conventional plastic pallet has a complicated shape, the molding becomes injection, injection compression, or extrusion compression, and each part corresponds to the mold However, in the present invention, it can be easily manufactured with a single molding machine and a molding die, and the desired properties, particularly high impact resistance, can be obtained. It is an object of the present invention to provide a pallet having high resistance and load resistance. Another object of the present invention is to provide a lightweight resin pallet having desired physical properties such as load resistance and impact resistance and having a rib structure.

[0008]

SUMMARY OF THE INVENTION A spring structure resin pallet according to the present invention comprises a continuous loop of thermoplastic resin and / or a random loop of short loops or curls which are adjacent to each other and are contact-entangled with each other. A pallet comprising a three-dimensional structure (hereinafter, referred to as a three-dimensional structure) having voids of a predetermined bulk density, wherein the fork insertion port of the pallet unit is located at both longitudinal ends of the fork insertion port and substantially at the center. A high-density portion formed by increasing the bulk density reaching both ends in the longitudinal direction and the width direction is formed, and at least the inner portion of the fork insertion opening or the outer peripheral edge and inner surface of the fork insertion portion has a volume equal to or lower than the high-density portion. It is characterized in that a flat portion having a density is formed.

According to the present invention, the continuous filaments and / or the short filaments are made of, for example, a thermoplastic elastomer, and the diameter of the continuous filaments and / or the short filaments is 0.1 to 10.
It is 3.0 mm, preferably 0.3 to 0.7 mm, and the bulk density of the structure of the three-dimensional structure is 0.1 to 0.9 g / cm ³ . Further, a flat portion having a bulk density equal to or less than the high density portion is formed on the outer peripheral surface of the pallet including the inner surface of the fork insertion port and the outer peripheral edge, or the high density portion and the portion other than the flat portion are flattened. It can be formed in a rough portion having a bulk density of not more than a part.

The diameter of the continuous line and / or the short line of the rough portion is 0.1 to 3.0 mm, preferably 0.7 to 1.5 mm.
And the bulk density of the three-dimensional structure is 0.01 to 0.
1 g / cm ^3, preferably, if 0.02~0.05g / cm ^3, and more, it is possible to reduce the weight.

Further, if the portion excluding the flat portion is a high density portion, the molding becomes easier by disposing two types of injection port groups, a rough portion and a high density portion.

Further, in the production method of the present invention, a thermoplastic resin and / or a thermoplastic elastomer is melt-extruded into a plurality of filaments so that adjacent filaments of continuous linear loops or curls are contact-entangled with each other. When molding a pallet consisting of a three-dimensional structure having voids of a predetermined bulk density, the drawing speed of the melt-extruded continuous filaments is changed to change the fork insertion port width direction high-density portion and flat portion, or Along with forming the two parts and the rough part, the fork insertion port is extruded through a core body, the fork insertion part longitudinal direction high density part and a flat part or the two parts and the rough part are , Extruding with different density of each injection port,
It is characterized in that it is formed by drawing.

At the time of pulling out, in the longitudinal direction of the fork insertion port of each pallet, the pulling speed is faster than that at the time of forming a rough portion in the longitudinal direction of the fork insertion port corresponding to the length of each pallet unit. Then, in the width direction of the fork insertion opening of each of the pallets, it is possible to continuously manufacture the pallets by cutting into the length of each of the pallets.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (Three-Dimensional Structure) A three-dimensional structure used in the present invention is a three-dimensional structure having continuous filaments and / or voids formed by randomly entangled short filaments. And the continuous line and / or the short line form a plurality of loops or curls. In such a three-dimensional structure, for example, a thermoplastic elastomer is melt-extruded from a plurality of injection ports at a predetermined extrusion speed and taken out by a take-off machine 13 to be described later to obtain a pure denier of 60 to 57,000 denier, preferably 570 to 14,300 denier. Alternatively, a hollow continuous filament is formed, and the filament in a molten state has, for example, a diameter of 1 to 10
mm, preferably a diameter of 1 to 5 mm is formed, and a pallet unit 30 is formed by taking out by a take-up machine 13 in water while forming a random loop by contacting and interlacing adjacent filaments in water. .

At least a part of the contact entangled portions are melt-bonded to each other.

For example, a single pallet 30 defined by JIS standard
The take-up speed of the take-up machine 13 is adjusted at intervals of
In FIG. 1 showing Comparative Example 1, the fork insertion port 23
A high-density portion H which becomes the horizontal block portions 33 to 35 in the pallet simplex 30 positioned in the direction orthogonal to the longitudinal direction.
(33 to 35) or the rough portion L on the outside of the portion H and the fork insertion port 23 is formed.

[0017] Pallet unit width 900 x length 900 x thickness 115 (mm) weight 10 kg Fork slot width 250 x length 900 x thickness 60 (mm)

As described above, the block portion located in the direction orthogonal to the longitudinal direction of the fork insertion port 23 has a portion H having a large bulk density at the time of low-speed take-up, that is, a high-density portion and the high density at the time of high-speed take-up. It can be manufactured by forming a three-dimensional spring structure of a predetermined thickness having a rough portion L other than. Further, the fork insertion port 23 is extrusion-molded through a male-shaped core body 17 described later that corresponds to the fork insertion port that is provided on the molding die 12 so as to project in the resin extrusion direction. The vertical block portions 42 to 44 which are high-density portions H in the longitudinal direction, the deck boards 52 and 53 on the front and back sides and the side surfaces 56 and 57, and the four inner side surfaces 54 and 55 of the fork insertion ports 23 and 23. The above-mentioned flat portion M or the above-mentioned two portions H, M and the rough portion L occupying the main portion of each pallet unit other than the above-mentioned two portions differ in the arrangement or density of the injection openings 18 formed by punching in the molding die 12. Then, it is extruded and drawn out.

At the time of pulling out, in the longitudinal direction of the fork insertion port 23 of each pallet unit 30, the pulling speed is set for a predetermined time corresponding to the length of each pallet unit 30 and the rough portion in the longitudinal direction of the fork insertion port. The cutting portion F where each fiber becomes substantially linear is formed earlier than when L is formed, and the length of each pallet unit 30 is adjusted to the length of each pallet unit 30 in the cutting device 19 in the fork insertion width direction of each pallet unit. It is manufactured continuously by the cutting step (FIGS. 2 and 3).

FIG. 4 shows a manufacturing device for cutting in the bus 15. The cutting device 19 is located near the lower part of the take-up machine 13 and is a pallet unit cut at the cutting portion F on the opposite side wall of the bus 15. The transport device 11 is composed of a conveyor having a large number of locking projections inserted into the voids. In the figure, 25 is a water absorption valve, and 26 is a drain valve.

The diameter of the continuous filament and / or the short filament is
It is 0.1 to 3.0 mm, preferably 0.3 to 0.7 mm.

The continuous filaments and / or the short filaments are preferably made of a thermoplastic elastomer, for example, polypropylene, polyester, nylon or PVC elastomer.

The bulk density of the three-dimensional structure is a rough part,
0.01-0.1 g / cm ³ , preferably 0.02-
0.05, 0.3-0.9 g / cm ³ at high density portions, preferably 0.5~0.7g / cm ^3. The middle flat portion has a density of 0.1 to 0.9 g / cm ³ , preferably 0.3 to
It is 0.7 g / cm ³ .

The porosity of the three-dimensional structure is 8 in the rough part.
8-99%, preferably 94-98%, especially 94-9
6%, 0-66% at high density part, preferably 22-
44%, especially 20-30%. The flat portion is located at an intermediate value between the two.

[0025]

[Formula 1] In the method for manufacturing the spring structure resin pallet 30 of the present invention, as shown in FIG. 3, a raw material resin, for example, a polypropylene elastomer is charged from the hopper of the extruder 10 and melt-kneaded to have a predetermined diameter provided in the molding die 12. While being extruded from a large number of injection ports of, the thickness and bulk density are set between the take-up rolls 14 of the take-up machine 13 in the bath 15, and the curls or loops are randomly formed,
It solidifies in the water of the bath 15, is taken out by the winders 16 and 16, is cut at the cutting portion F by the cutting device 19, and is taken out as the spring structure resin pallet 30.

FIG. 5 shows an outline of the molding die 12. As described above, the core body 17 has a male shape described later, which corresponds to the fork insertion port protruding in the resin extrusion direction. The injection port 18 has an injection port diameter, an arrangement, and an arrangement so as to form the flat part M, the high-density part H, and the rough part L occupying the main part of each pallet other than the two parts in order to determine the bulk density in the pallet extrusion direction. The number is defined.

Embodiment 1 (FIG. 7) In addition to the fork insertion holes 23, 23, a hollow portion 36 is formed in approximately three divided positions in the width direction of the pallet unit 30. Manufactured by means of correspondingly configured forming dies and therefore the longitudinal blocks (42, 4
2 ', 43, 44', 44) are provided twice correspondingly. The structure is lighter and has a rib structure. Further, a rib 37 composed of four flat portions M is formed between the inner surface of the fork insertion holes 23, 23 facing the front and back deck boards 52, 53 and the flat portion M of the front and back deck boards 52, 53. Has been done. Further, the blocks 33 'and 35' in the horizontal direction are added to the two equally divided positions.

[0028] Pallet unit width 1100 x length 1100 x thickness 150 (mm) weight 18 kg Fork slot width 250 x length 1100 x thickness 70 (mm)

FIG. 6 shows a mechanism for mounting a reinforcing member according to the present invention, in which the lower end of the inclined shooter 62 is arranged so as to face the upper end portion of the take-up machine 13 and the upper end of the shooter 62 is supplied to the reinforcing member feeder. It communicates with 61. 63 is
It is a gate for quantitatively supplying the reinforcing member 60. Although a plurality of shooters 62 can be provided to correspond to a reinforcing member described later or another design, in the illustrated embodiment 1,
It is configured in two rows [FIG. 6 (B)] and corresponds to the opening / closing interval of the gate 63 in which the reinforcing member is a solenoid valve at the same time for two pieces in parallel with the thickness direction on both sides in the thickness direction. For example, a plurality of them are placed in parallel in the low-density region L at appropriate intervals,
Will be installed. Further, when a reinforcing member is mounted in the longitudinal direction, a hollow portion is formed at the time of molding at a desired mounting portion of the reinforcing member by closing the hole of the nozzle or through the core body 17, and the hollow portion is formed in the hollow portion after molding cutting. Attach the reinforcing member. In Examples 1 and 2, the reinforcing member uses a waste material such as a bolt, a nut, or other metal parts. In this case, the shooter 62 has a shape and size corresponding to the reinforcing member. In Example 3 described later, the outer diameter is 12 mm,
It is also possible to use a pipe-shaped metal (iron, stainless steel) having an inner diameter of 8 mm and a length of 1,100 mm.

Example 2 (FIG. 8) Example 2 shows a production example in which the height and the thickness are lower or thinner than those in Example 1, and the hollow portion 36 and the blocks in the vertical direction are the same as in Example 2. There are horizontal blocks,
The pallet unit 30 has a thin shape including the edges of both ends, and is formed as a high-density region H at three divided positions in the longitudinal direction of the pallet unit 30.

Then, unlike the first embodiment, the inner side surfaces 54 and 55 facing the front and back deck boards 52 and 53 of the fork insertion holes 23 and 23 and the front and back deck boards 52 and 53, respectively.
Between the flat portions M of 53, two ribs 38 formed of high-density portions H are formed in the vertical direction from both widthwise end edges of the inner side surface. Pallet alone Width 1100 x Length 1100 x Thickness 115 (mm) Weight 10 kg Fork slot Width 250 x Length 1100 x Thickness 60 (mm)

For the test resin pallet, the test results based on the JIS Z0602 flat pallet test method based on the JIS Z0606 plastic flat pallet are shown below.

Test Example 1 (Comparative Example; FIG. 1) Maximum load: 1.0t

[0034]

[Table 1]

Test Example 2 (Example 1: FIG. 7) Maximum load: 1.5t

[0036]

[Table 2]

Test Example 3 (Example 2: FIG. 8) Maximum load: 1.0t

[0038]

[Table 3] It is obvious that it corresponds to Class A of JIS Z0606 plastic flat pallet.

Example 3 (reinforcement member mounted product; FIG. 9) As shown in FIGS. 6 and 9, the reinforcing member 60 was attached.

Reinforcement in the width direction is 12 mm in outer diameter and 8 mm in inner diameter.
A stainless steel pipe 60 having a length of 1 mm and a length of 1100 mm is mounted in the width direction on the rough portions directly below the deck boards 52 and 53 on the front and back. The number of attachments is 4 on each of the front and back sides.

Reinforcement in the longitudinal direction is provided by the high density portion H (42-
Molding is performed with a core body so that a hole of φ11 mm is formed immediately below (center side) the width direction reinforcing member of 44). After molding, outer diameter φ
12mm inner diameter φ8 length 1100mm stainless steel pipe 60
Two pieces are attached to each of 42 to 44. The number of attachments is 6
It is a book. Pallet alone Width 900 x Length 900 x Thickness 115 (mm) Weight 14 kg Fork slot Width 250 x Length 900 x Thickness 60 (mm) Maximum load 1.5t

[0042]

[Table 4] It is clear that it corresponds to Class A of JIS Z 0606 plastic flat pallet.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment (comparative example) of the present invention, (A) is a plan view, (B) is a side view, and (C) is the same view (A).
AA line sectional view, (D) is the same figure (A) BB line sectional view,
(E) is a sectional view taken along line CC of FIG.

FIG. 2 is an overall perspective view showing the outline of the manufacturing apparatus of the present invention.

FIG. 3 is an overall view showing an outline of another manufacturing apparatus of the present invention.

FIG. 4 is an overall view showing the outline of still another manufacturing apparatus of the present invention.

FIG. 5 is a schematic diagram (A) of a front view of the molding die of the present invention;
(B) is a partially enlarged view of the injection port portion, (C) is a partial schematic bottom view

FIG. 6 is a front view and FIG. 6B is a partially enlarged view showing the outline of a weight insertion device which is a part of the manufacturing apparatus of the present invention.

7A and 7B are schematic views showing another embodiment (Example 1) of the present invention, FIG. 7A is a plan view, FIG. 7B is a side view, and FIG. (D) is a cross-sectional view taken along the line (A) BB in the same figure, (E) is a cross-sectional view taken along the line (A) CC in the same figure, and (F) is
Part C enlarged view of FIG.

8A and 8B are schematic views showing still another embodiment (Example 2) of the present invention, FIG. 8A is a plan view, FIG. 8B is a side view, and FIG. , (D) is a sectional view taken along the line (A) BB in the same figure, and (E) is a sectional view taken along the line (A) CC in the same figure.

9A and 9B are schematic views showing still another embodiment (Example 2) of the present invention, FIG. 9A is a plan view, FIG. 9B is a side view, and FIG. 9C is a sectional view taken along line AA in FIG. 9A. , (D) is a sectional view taken along the line (A) BB in the same figure, and (E) is a sectional view taken along the line (A) CC in the same figure.

[Explanation of Codes] 10 Extruder 11 Conveying Device 12 Forming Die 13 Pulling Machine 14 Pulling Roll 15 Bus 16 Winding Machine 17 Core 18 Injection Port 19 Cutting Device F Cutting Part L Rough Part H High Density Part M Flat Part 23 Fork insertion port 25 Water supply valve 26 Drain valve 30 Spring structure Resin pallet 33, 34, 35, 33 ', 35' (lateral direction) Block part 36 Hollow part 37, 38 Ribs 42, 43, 44 (longitudinal direction) Block part 52,53 front and back deck boards 54,55 fork insertion port inner side surfaces 56,57 side deck board 60 reinforcing member 61 reinforcing member feeder 62 shooter 63 gate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16F 7/00 F16F 7/00 B 15/04 15/04 FZ F term (reference) 3E063 AA04 BA05 CA01 EE01 GG03 3J048 AA01 AB01 BD01 EA10 EA13 3J059 AB11 AD06 BA41 BC04 BC05 BD01 BD03 BD04 BD05 EA03 EA04 GA50 3J066 AA01 AA22 AA26 AA29 BA01 BB01 BB04 BC01 BD05 4F207 AD18 AG02 AG14 AH56 KA01 KA12 KA12 KA12 KK17 KK17 KK

Claims (9)

[Claims] 1. A three-dimensional structure provided with voids having a predetermined bulk density, which are formed by contact-entangled assembly of continuous filaments and / or short filaments of random loops or curls of adjoining filaments of a thermoplastic resin. In the pallet consisting of the pallet, a high-density portion is formed at both ends of the fork insertion port in the longitudinal direction and substantially in the center of the pallet, the bulk density reaching the both ends of the fork insertion port in the longitudinal direction and the width direction being increased. And, at least the inner surface of the fork insertion opening or the outer peripheral edge and inner surface of the fork insertion opening is formed with a flat portion having a bulk density equal to or lower than the high density portion, and the high density portion and / or the low density portion is reinforced. A resin pallet with a spring structure that is equipped with members. 2. The resin pallet having a spring structure according to claim 1, wherein the continuous filaments and / or the short filaments are made of a thermoplastic elastomer. 3. The spring according to claim 1, wherein the continuous wire and / or the short wire has a diameter of 0.1 to 3.0 mm, preferably 0.3 to 0.7 mm. Structural resin pallet. 4. The bulk density of the structure of the three-dimensional structure is 0.
Claim, characterized in that a 1~0.9g / cm ³ 1~3
The spring structure resin pallet according to any one of the items. 5. The spring structure resin pallet according to claim 1, wherein the high density portion and the portion other than the flat portion are formed in a rough portion having a bulk density equal to or lower than the flat portion. 6. The bulk of the structure of the three-dimensional structure, wherein the continuous line and / or the short line of the rough portion has a diameter of 0.1 to 3.0 mm, preferably 0.7 to 1.5 mm. The density is 0.01 to 0.
1 g / cm ^3, preferably, a spring structure resin pallet according to claim 5, characterized in that the 0.02~0.05g / cm ^3. 7. The flat portion having a bulk density equal to or lower than the high density portion is formed on the inner surface of the fork insertion opening or the outer peripheral surface of the pallet including the outer peripheral edge of the fork insertion opening. Spring structure resin pallet. 8. A thermoplastic resin and / or a thermoplastic elastomer is melt-extruded into a plurality of filaments so that adjacent filaments of random loops or curls of continuous filaments are brought into contact and entangled with each other to obtain a predetermined bulk density. When molding a pallet consisting of a three-dimensional structure having voids, the withdrawal speed of the melt-extruded continuous filaments is changed to form a high density portion in the fork insertion port width direction, a flat portion or the two portions and a rough portion. To form
In the step of forming the high density portion, the flat portion or the two portions and the rough portion, a reinforcing member is put into the high density portion and / or the low density portion, and the fork insertion port is extruded through the core body. Then, the high density portion, the flat portion or the two portions and the rough portion in the longitudinal direction of the fork insertion port are extruded with different densities of the ejection ports, and are formed by pulling out. Method. 9. When pulling out, in the longitudinal direction of the fork insertion port of each pallet unit, the pulling speed is made faster than that at the time of forming the rough portion in correspondence with the length of each pallet unit. A method of manufacturing a spring structure resin pallet, characterized in that the pallet is cut to the length of each pallet in the fork insertion width direction.