JPH11124136A - Synthetic resin pallet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin pallet having a superior gas feeding balance when a hollow part is formed by feeding gas into a reinforcing rib so as to attain its light weight and high bending strength. SOLUTION: A synthetic resin pallet is made such that pallet forming members 10, 20 having such shapes as one in which a pallet is divided into an upper section and a lower section are formed by an injection molding operation and these members are oppositely faced against to each other, melted and adhered integrally. The pallet includes central beams arranged at the central part of the synthetic resin pallet so as to define and form fork insertion passages and having their inner parts as a closed space, surrounding beams spaced apart by a predetermined space around the central beams and gas flowing ribs formed inside the central beams and formed in a radial direction from the inner side of the central beams. When the pallet forming members are molded, gas is blown from inside of each of the central beam forming members 12a, 12b becoming the central beams and then the gas is flowed into all the relative large reinforcing ribs 15, 25 arranged in the pallet forming members 10, 20 through the gas flowing ribs 16, 26, thereby a hollow section is formed at the reinforcing ribs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pallet made of synthetic resin, and more particularly to a pallet for a forklift used for carrying, moving, and storing articles.

[0002]

2. Description of the Related Art Conventionally, synthetic resin pallets have been manufactured and used as forklift pallets.
Normally, this type of synthetic resin pallet is basically formed by injection molding a pallet forming member having a shape in which the pallet is vertically divided at a girder portion, and these two pallet forming members are integrated by heat welding. Formed.

[0003] There are various types of synthetic resin pallets, and here, a description will be given of a pallet made of two members having slightly different structures. When forming such a synthetic resin pallet, first, the upper and lower pallet forming members are formed by injection molding.

[0004] The upper pallet forming member includes a deck board for forming a loading surface, a girder forming member provided at an appropriate position on the inner surface of the deck board, and a comparatively provided crosswise and longitudinally provided on the inner surface of the deck board. It has thick reinforcing ribs.

The lower pallet forming member has a similar spar forming member at a position corresponding to the spar forming member of the upper pallet forming member, and a relatively thick reinforcing rib inside the bottom surface. The pallet forming members of the upper die and the lower die are opposed to each other, butts the spar forming members, and the butted portions are welded and integrated by heat to form a synthetic resin pallet.

[0006] Forming such relatively thick reinforcing ribs on the inner surface of each pallet forming member increases the bending strength of the deck board and the bottom surface, and transports the load with a forklift.
It is well known that it is extremely effective in preventing the deck board from bending when moving or the like.

[0007]

However, such a relatively thick reinforcing rib has a great effect in increasing the bending strength of the deck board as described above, but on the other hand, the synthetic resin pallet has a corresponding effect. There was a problem that the weight increased. In addition, there is also a problem that heat tends to stay in the deck board and the bottom portion where the reinforcing ribs are formed at the time of molding, and solidification is delayed, so that sinks occur and the surface of the deck board is depressed along the reinforcing ribs. Was.

Further, when forming a synthetic resin pallet, a groove may be formed on the deck board surface located immediately above the reinforcing rib, and a band-shaped non-slip may be arranged in this groove.
In such a case, the bottom of the groove is concavely concaved due to the above-mentioned "sinking", so that even if a non-slip is arranged in the groove, there is a problem that the non-slip does not function effectively.

[0009] Therefore, it has been proposed to blow gas into relatively thick reinforcing ribs immediately after injection molding the pallet forming member and to flow into the inside thereof, thereby forming a hollow portion in the reinforcing ribs. It has been implemented. Blowing a gas into a relatively thick reinforcing rib to form a hollow portion is well known as a gas injection method.

When a hollow portion is formed in a relatively thick reinforcing rib using this gas injection method, the above-mentioned generation of sink marks can be prevented, and the weight of the entire synthetic resin pallet can be greatly reduced. is there. However, conventionally, when forming a synthetic resin pallet, there is no particular problem regarding the gas injection position, and gas is blown from a plurality of appropriate locations at the reinforcing rib formation position where a hollow portion is to be formed. Was out.

However, when examining the molded synthetic resin pallet, it is found that the gas injection balance is poor or the thickness of the reinforcing rib having the hollow portion is not constant and the weight is not well balanced. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem. When forming a hollow portion by gas injection in a reinforcing rib so as to have a light weight and a large bending strength, gas injection is performed. It is to provide a well-balanced synthetic resin pallet.

[0013]

SUMMARY OF THE INVENTION The present invention is a synthetic resin pallet, and is configured as follows to achieve the above-mentioned technical object. That is, the present invention is a synthetic resin pallet in which a pallet formed by dividing a pallet into upper and lower parts is formed by injection molding, and these are opposed to each other and welded and integrated, and a passage for inserting a fork is defined. A central girder is provided at the center of the synthetic resin pallet to be formed, and a central girder whose interior is an enclosed space and a peripheral girder provided at a predetermined interval around the central girder, and are formed inside the central girder, A gas flow rib formed radially from the inside of the center girder, and when molding the pallet forming member, gas is blown from the inside of the center girder formation member serving as the center girder through the gas flow rib. The hollow portion is formed in the reinforcing rib by flowing into all the relatively thick reinforcing ribs provided on the pallet forming member.

<Specific Structure of the Present Invention> The synthetic resin pallet of the present invention is composed of the above-mentioned essential components, but the present invention can be established even when the specific components are as follows. The concrete component is that reinforcing ribs are formed between adjacent peripheral girders, and between a central girder and peripheral girders located in the vertical and horizontal directions, respectively, and reinforcing ribs connected to the central girder are provided inside the central girder. It is characterized in that it is connected to the gas distribution rib via the wall of the central girder.

Further, the synthetic resin pallet of the present invention is a four-sided pallet, which is provided with one central girder and eight peripheral girths arranged vertically and horizontally around the central girder, and a vertical direction passing through the center of the central girder. When viewed in a quarter area of the synthetic resin pallet, which is virtually divided by the center line and the lateral center line, the reinforcing ribs are formed at positions almost inscribed in the four girders. And

Furthermore, in the synthetic resin pallet of the present invention,
A deck board is provided on one of the two pallet forming members constituting the pallet, and the other pallet forming member is formed at a position where the four girders are substantially inscribed when viewed in a quarter area of the synthetic resin pallet. An opening is formed on a surface surrounded by the provided reinforcing ribs.

According to the synthetic resin pallet of the present invention, as a whole, a pallet forming member having a shape obtained by dividing the pallet into upper and lower parts is formed by injection molding, and these are formed by opposing and welding and integrating. When each pallet forming member is formed by injection molding, the inside of the central girder forming member formed at the center of the pallet forming member before the inside of the reinforcing ribs provided vertically and horizontally on the inner surface of the deck board and the inner surface of the bottom surface solidifies Preferably, a gas is injected into the reinforcing ribs from a central position, and the gas is radially flowed and spread into each reinforcing rib, and a hollow portion is formed therein.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a pallet made of synthetic resin according to the present invention. FIG. 1 is a detailed plan view of a four-sided synthetic resin pallet according to one embodiment of the present invention, which is divided into upper and lower halves, and a quarter of the upper pallet forming member 10 is viewed from the inside. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, and FIG. 3 is a sectional view taken along line 3-3 in FIG.

FIG. 4 shows a lower pallet forming member 20.
5 is a schematic plan view of the lower pallet forming member 20 shown in FIG. 4 as viewed from the inside, and FIG. 6 is a detailed plan view of the lower mold pallet forming member 20 shown in FIG. 5 of 6
7 is a cross-sectional view taken along the line 7-7 in FIG. 5, and FIGS. 8 to 11 are cross-sectional views showing reinforcing ribs having different cross-sectional shapes.

As shown in FIG. 1, the upper die pallet forming member 10 is arranged neatly at predetermined intervals vertically and horizontally inside a deck board 11 (the entire arrangement of the beam forming members in the pallet forming member is shown in FIG. 1). 4) and nine girder forming members 12a and 13a.

That is, these nine beam forming members 12
a and 13a, reference numeral 12a denotes one central girder forming member having a substantially rectangular cross section provided at the center of the pallet forming member 10, and reference numeral 13a denotes a deck board so as to surround the central girder forming member 12a. 11 shows eight peripheral girder forming members provided along the peripheral edge of 11.
The thickness of the beam forming members 12a and 13a is about 3 to 7
mm.

The upper pallet forming member 10
On the inside of the deck board 11, relatively thin reinforcing ribs 14 are provided to intersect vertically and horizontally. A large number of such relatively thin reinforcing ribs 14 are provided inside the surrounding girder forming member in order to improve the strength of the deck board 11 and also to counter impacts from the outside of the surrounding girder forming member. .

The pallet made of synthetic resin is a four-sided pallet as described above, and the upper pallet forming member 10 is composed of one central girder forming member 12a and eight peripheral pallets arranged in line therearound. And a beam forming member 13a. Then, when viewed about a quarter area (FIG. 1) of the synthetic resin pallet, which is virtually divided by a vertical center line and a horizontal center line passing through the center of the center girder forming member 12 a, four A relatively thick reinforcing rib 15 is formed at a position where the beams 12a and 13a are substantially inscribed.

FIG. 8 shows an example of the cross-sectional shape of the reinforcing rib 15. The reinforcing rib 15 has a width L in the range of 5 to 40 mm, preferably 8 to 20 mm, and a height H from the surface of the deck board 11 of 20 to 50 mm, preferably 25 to 25 mm.
４０40 mm.

Thus, at each corner of the central girder forming member 12a, two reinforcing ribs 15 extending from the peripheral girder forming member 13a arranged in the vertical and horizontal directions of the central girder forming member 12a.
Are connected (see FIG. 4). Gas distribution ribs 16 are formed at diagonal positions inside the central girder forming member 12a, and the ends of these gas distribution ribs 16 are connected via the wall of the central girder forming member 12a.

As a result, all of the reinforcing ribs 15 provided between the beam forming members 12a and 13a
In FIG. 8, the reinforcing ribs 15 connected to the gas distribution ribs 16 all connected to the gas distribution ribs 16 provided in the X shape in FIG. Hollow portion 17 is formed as described above.

Next, a method of forming the hollow portion 17 inside the reinforcing rib 15 will be described. The intersection 18 of the gas distribution ribs 16 arranged in the X shape in the center girder forming member 12a is the center point of the center girder forming member 12a and also the center point of the pallet forming member 10. The intersection of the X-shaped gas distribution ribs 16 is the gas blowing position.

That is, a pallet forming die (not shown) for forming the pallet forming member 10 has one gas injection hole (not shown) at a portion corresponding to the center position inside the pallet forming member 10 described above. Is provided. Then, when the molten resin is injected from a separately provided dedicated hole for injection of the molten resin and the pallet forming member 10 is injection molded, air or air is injected from the gas injection hole before the inside of the reinforcing rib 15 and the gas distribution rib 16 is solidified. A suitable gas such as nitrogen is injected.

The gas injected from the gas injection hole enters all the reinforcing ribs 15 from the intersection 18 of the gas distribution ribs 16 via the ribs 16 and enters the hollow portions 17 therein.
To form Therefore, the hollow part 17 shown in FIG. 8 is also a conduction path for the injected gas formed in the reinforcing rib 15, and the conduction path in the reinforcing rib 15 is all in communication with the hollow part 17 of each of the reinforcing ribs 15 and 16. Will be.

An opening serving as a gas injection port is formed at the intersection after gas is blown from the intersection 18 of the gas distribution ribs 16, and the hollow portion 17 in the reinforcing rib 15 passes through the gas injection port. To communicate with the atmosphere. For convenience, this gas inlet is also denoted by reference numeral 18.

As described above, when the molten resin is injected into the mold and molded, before the molten resin injected into the mold is solidified, a gas such as air or nitrogen is blown to form a hollow portion in the reinforcing rib. Since the formation method is well known as a gas injection method, a detailed description of this method is omitted.

Since the internal pressure of the gas blown into the reinforcing ribs 15 from the gas distribution ribs 16 acts evenly on the inner wall of the mold, the thickness of the formed reinforcing ribs 15 becomes extremely thin. Never. Thus, the reinforcing rib 15
By forming the hollow portion 17 therein, effects such as a reduction in the weight of the synthetic resin pallet, a reduction in dimensional fluctuation during molding, and a reduction in molding time are obtained.

The amount of gas injected into the reinforcing ribs 15 during the injection molding of the pallet forming member 10 is adjusted according to the required strength of the synthetic resin pallet 10 and the like. Usually, it is preferable to inject gas so that the apparent density of the entire synthetic resin pallet is about 0.75 to 0.95 times the density of the raw synthetic resin.

On the other hand, the lower pallet forming member 20 shown in FIG. 4 and FIG.
A center girder forming member 12b and a peripheral girder forming member 13b are provided. These girder forming members 12b and peripheral girder forming members 13b are exactly the same as the corresponding girder forming members 12a, 13a in the above-described upper die pallet forming member 10 in the forming position, cross-sectional shape and size.

The lower pallet forming member 20 is also virtually divided by a vertical center line and a horizontal center line passing through the center of the center girder forming member 12b, and is one-fourth of the synthetic resin pallet. When looking at the area (FIG. 5), four digits 12
A relatively thick reinforcing rib 25 is formed at a position where b and 13b are substantially inscribed.

However, like the above-mentioned upper pallet forming member 10, the reinforcing ribs 25 extending from the peripheral spar forming member 13b and the center spar forming member 12b provided at the corners of the pallet forming member 20 are formed by pallet forming. The peripheral edges of the members 20 are not connected to each other outside the corners of the peripheral girder forming member 13b provided at the intermediate portion.

For this reason, in order to substantially connect the reinforcing rib 25 with the peripheral girder forming member 13b provided at an intermediate portion of the peripheral edge of the pallet forming member 20, a reinforcing rib 22 for connection is provided along the inner surface of the wall. Have been. Thereby, the peripheral girder forming members 13 arranged in the longitudinal direction and the horizontal direction of the central girder forming member 12b are provided at each corner of the central girder forming member 12b.
Two reinforcing ribs 25 extending from b will be connected.

Gas distribution ribs 26 are formed inside the center girder forming member 12b at diagonal positions, and the ends of these gas distribution ribs 26 are connected to the center girder forming member 12b.
And a gas injection port is finally formed at the intersection 28 as in the case of the upper pallet forming member 10. For convenience, this gas inlet is also designated by reference numeral 28.

As a result, all of the reinforcing ribs 25 provided between the beam forming members 12b and 13b are
In other words, it is connected to the gas distribution rib 26 provided in the X-shape in b. As shown in FIG. 8, a hollow portion 27 is formed inside the reinforcing rib 25 which is all connected to the gas distribution rib 26. The method of forming the hollow portion 27 in the reinforcing rib 25 is the same as the method of forming the hollow portion 17 in the reinforcing member 15 of the upper die pallet forming member 10, and a description thereof will be omitted.

The lower pallet forming member 20
As shown in FIG. 5, when viewed in a quarter area of the synthetic resin pallet, four beam forming members 12b, 1
An opening 23 is formed in a portion surrounded by a reinforcing rib 25 formed at a position substantially inscribing 3b. The opening portion 23 is a portion serving as a doorway of a wheel when the synthetic resin pallet is handled by a hand lift.

The synthetic resin pallet according to this embodiment is
The upper and lower pallet forming members 10 and 20 are opposed to each other, and the beam forming members 12a, 12b and 13
a and 13b are butted, and the butted part is welded and integrated. In this way, the upper and lower pallet forming members 10 and 20 are opposed to each other, and
A hollow cylindrical girder is formed by abutting and integrating the 2b and 13a, 13b by welding and the space (hole) between these girders becomes a fork insertion hole.

Since the spar of the synthetic resin pallet thus formed has a closed hollow cylindrical shape, it is formed on the upper and lower pallet forming members 10 and 20 located in the center spar, respectively. The gas injection ports 18 and 28 are not exposed to the outside (atmosphere). Therefore, during use of the synthetic resin pallet, rainwater is supplied to the gas injection ports 18 and 28.
Can also be prevented from entering the hollow portion 17 in the reinforcing ribs 15 and 25 via the ribs.

In the synthetic resin pallet of this embodiment, a groove 30 may be formed on the deck board surface immediately above the reinforcing rib 15 and a slip stopper 31 may be arranged in the groove 30. At this time, since the hollow portion 17 is formed inside the reinforcing rib 15 as described above,
It is possible to prevent the occurrence of dents due to “sink” on the bottom surface of the groove 30.

As a result, as shown in FIG. 8, the surface of the non-slip 31 slightly projecting from the surface of the deck board 11 can be positioned substantially parallel to the surface of the deck board. Can be demonstrated.

Next, the injection molding conditions for the pallet forming members 10 and 20 will be described. Pallet forming members 10, 2
The injection molding conditions of 0 may be ordinary conditions. For example, when high-density polyethylene is used as a material, the melting temperature (cylinder temperature) is 200 to 250 ° C., and the injection rate is 2000 to 50.
A condition of about 00 cc / sec is preferable. Further, as a synthetic resin constituting the pallet, polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer or the like is generally used, but it goes without saying that other resins may be used in some cases.

Further, it goes without saying that additives such as a coloring agent and a filler may be appropriately used. Furthermore, a foaming material may be mixed with these synthetic resins by mixing a conventionally known blowing agent including a commonly used organic or inorganic one. The foaming ratio in this case is desirably about 1.01 to 1.4 times. In this case, the apparent density of the entire pallet is preferably about 0.65 to 0.95 times the density of the raw synthetic resin.

In the synthetic resin pallet according to the above-described embodiment, the reinforcing ribs 15 and 25 provided inside the pallet forming members 10 and 20 are formed so as to connect the girders. There is no reason to limit the arrangement of the ribs 15, 25 in this way. In short, it is only necessary to connect all the reinforcing ribs that are to form hollow portions inside, and finally connect them to the gas distribution ribs provided in the central girder forming member.

In FIG. 1, reference numeral 32 indicates that when the present synthetic resin pallet is used, a relative slip between the fork and the synthetic resin pallet does not occur when the fork is inserted into the fork insertion hole. Deck board 1
1 shows a non-slip rubber grommet press-fitted into a hole provided at a crossing portion of a reinforcing rib 14 formed on the inner surface of No. 1.

In one embodiment of the synthetic resin pallet of the present invention described above, the cross-sectional shape of the reinforcing rib 15 is substantially square as shown in FIG. 8, but the present invention is not limited to this shape. Absent. For example, a reinforcing rib having a curved side surface as shown in FIG. 9, a reinforcing rib having a trapezoidal cross section having an inclined side surface as shown in FIG. 10, and a semicircular shape as shown in FIG. A reinforcing rib having a cross-sectional shape may be used.

The reinforcing rib 15 has a curved portion 19 at the thickest portion near the intersection with the deck board.
Is provided, and the size of the hollow portion due to the gas blown during molding can be controlled by appropriately designing the size of the curved portion. This is because, by increasing the substantial thickness of the reinforcing rib 15 near the intersection with the deck board as the curved portion 19, the flow of gas is promoted, and the gas flow path is easily formed. As a result, the gas can flow into the intended place.

[0051]

As described above, according to the synthetic resin pallet of the present invention, when the upper or lower pallet forming member is welded and integrated to form the synthetic resin pallet,
Connecting all the relatively thick reinforcing ribs provided on the inner surface of the deck board or the inner surface of the bottom surface, injecting gas from the inside of the girder provided in the center and flowing it in, thereby forming a hollow portion in the reinforcing ribs Therefore, the hollow portion can be formed with good balance.

Further, according to the synthetic resin pallet of the present invention, as described above, since there is no occurrence of depression due to sink marks on the deck board surface, even when a groove is formed at that position and a non-slip is arranged. Since the position of the non-slip surface is formed as designed, the function of the non-slip can be sufficiently exhibited.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a further quarter portion of an upper die pallet forming member in a synthetic resin pallet according to an embodiment of the present invention, which is formed by integrating vertically divided pallet forming members. It is.

FIG. 2 is a sectional view showing the pallet forming member shown in FIG. 1 cut along line 2-2.

FIG. 3 is a sectional view showing the pallet forming member shown in FIG. 1 cut along line 3-3.

FIG. 4 is a cross-sectional view schematically showing the entirety of a lower pallet forming member in a synthetic resin pallet according to an embodiment of the present invention, which is formed by integrating vertically divided pallet forming members.

FIG. 5 is a cross-sectional view showing a further quarter portion of the upper pallet forming member in the synthetic resin pallet according to one embodiment of the present invention, which is formed by integrating vertically divided pallet forming members. It is.

FIG. 6 is a sectional view showing the pallet forming member shown in FIG. 5 cut along line 6-6.

FIG. 7 is a sectional view showing the pallet forming member shown in FIG. 5 cut along line 7-7.

FIG. 8 is a cross-sectional view showing a cross-sectional shape of a reinforcing rib provided on the inner surface of the deck board in the synthetic resin pallet according to the embodiment of the present invention.

FIG. 9 is a cross-sectional view showing another cross-sectional shape of the reinforcing rib provided on the inner surface of the deck board in the synthetic resin pallet of the present invention.

FIG. 10 is a cross-sectional view showing still another cross-sectional shape of the reinforcing rib provided on the inner surface of the deck board in the synthetic resin pallet of the present invention.

FIG. 11 is a cross-sectional view showing still another cross-sectional shape of the reinforcing rib provided on the inner surface of the deck board in the synthetic resin pallet of the present invention.

[Explanation of symbols]

Reference Signs List 10 Upper pallet forming member 11 Deck board 12a Central girder forming member in upper pallet forming member 12b Central girder forming member in lower pallet forming member 13a Peripheral girder forming member in upper pallet forming member 13b Lower pallet forming member Peripheral girder forming member in pallet forming member 14 Relatively thin reinforcing rib 15 Relatively thick reinforcing rib 16 Gas flow rib 17 Hollow portion 18 Gas injection position (port) 20 Lower pallet forming member 21 Bottom surface 22 For connection Reinforcement rib 23 Opening 25 Reinforcement rib 26 Gas distribution rib 27 Hollow part 28 Gas injection position (mouth)

Claims (4)

[Claims] 1. A synthetic resin pallet in which a pallet formed by dividing a pallet into upper and lower parts is formed by injection molding, and these are opposed to each other and welded and integrated, and a passage for inserting a fork is defined. To be provided in the center of the synthetic resin pallet, a central girder having a closed space inside and a peripheral girder provided at a predetermined interval around the central girder, and formed inside the central girder, A gas distribution rib formed radially from the inside of the central girder, and at the time of molding the pallet forming member, gas is blown from the inside of the central girder forming member serving as the central girder, via the gas distribution rib. A hollow portion formed in the reinforcing ribs by flowing into all the relatively thick reinforcing ribs provided on the pallet forming member. Ltd. palette. 2. The reinforcing ribs are formed between adjacent peripheral girders and between the central girders and the peripheral girders located in the vertical and horizontal directions, respectively, and the reinforcing ribs connected to the central girder are formed by the reinforcing ribs. 2. The synthetic resin pallet according to claim 1, wherein the pallet is connected to the gas flow rib in the center girder via a wall of the center girder. 3. 3. The pallet made of synthetic resin is a four-sided pallet, wherein one central girder and eight surrounding girders are arranged vertically and horizontally around the central girder, and the center girder passes through the center of the central girder. When viewed in a quarter area of the synthetic resin pallet, which is virtually divided by a directional center line and a lateral center line, the reinforcing ribs are formed at positions substantially inscribing the four girders. The synthetic resin pallet according to claim 2, wherein 4. One of the two pallet forming members constituting the synthetic resin pallet has a deck board on a surface thereof, and the other pallet forming member is provided for a quarter area of the synthetic resin pallet. 4. The synthetic resin pallet according to claim 3, wherein an opening is formed on a surface surrounded by the reinforcing rib formed at a position where the four girders are substantially inscribed when viewed. 5.