This application is a National Stage application of International Patent Application No. PCT/IB2021/053569, filed Apr. 29, 2021, which claims the priority of Swiss patent application 00549/20, filed May 7, 2020, the disclosure of each of which is incorporated herein by reference in its entirety.
The invention relates to a plastic pallet with an upper part and three or more skids.
Pallets are used for storage and transportation of goods. The pallets keep the goods off the ground so that they can be lifted and transported by a forklift truck. They usually consist of a flat upper part and, in the case of pallets in the size of 1200×800 mm, three skids, which can be produced in one piece by injection molding or in multiple pieces. Multi-part plastic pallets are easier and cheaper to produce and consist, for example, of an upper part and a lower part which are connected in an interlocking manner. The lower part usually has three skids and nine feet.
The upper part and the lower part, or the skids, can be connected by welding, as described in CH702628 or CH685549. When the upper part is welded to the lower part, a bead is formed which must be removed by a milling operation so that the pallet has a smooth surface. This is time consuming and expensive.
Furthermore, the multiple parts can be connected to one another via snap locks. GB2421939 discloses a plastic pallet having a planar upper part and a planar lower part as well as nine separate feet via which the upper and lower parts are connected to each other, both ends of the feet being attached in each case to the upper and lower parts of the pallet by means of snap locks.
U.S. Pat. No. 5,483,899 discloses a pallet having a lower part and an upper part which can be pushed into one another, the lower part of the pallet having ribs with a snap element arranged at the upper end of each rib. By means of this snap element at the upper end of the ribs of the lower part of the pallet, the snap connection with the upper part is obtained.
From EP2733084, a plastic pallet is known with an upper part and a lower part, wherein the feet of the upper part and the lower part can be pushed completely into each other and locked by means of snap connections. In this case, the outer region of the feet is formed by the skids.
U.S. Pat. No. 5,794,543 A describes a modular pallet system with individual lower bottom elements and an upper element with a primary surface. In addition, the system includes complementary engagement elements of the upper and lower elements that interlock and connect the upper and lower elements together.
The known multi-part plastic pallets have the disadvantage that the connection between the different parts can disengage under continuous load and the upper part separates from the feet or skids, respectively.
It is now the object of the present invention to provide a multi-part plastic pallet which permits a connection between the upper part and the skids, wherein this connection is able to better withstand the load caused by an impact of the pallets during transport and, if possible, does not open even under high load.
This object is achieved by a plastic pallet with an upper part and skids, the upper part being provided with outer and middle female foot parts and the skids being provided with outer and middle male foot parts, wherein the male foot parts of the skids can be pushed into the female foot parts of the upper part, and wherein in the assembled state of the plastic pallet, the male foot parts together with the female foot parts form feet. The foot parts of the upper part and the foot parts of the skids can be fastened to one another by means of snap connections. Each male foot part comprises at least two snap hooks which are arranged with mirror symmetry in pairs and which each have a hook head with undercut, a snap arm and a rear side, the undercuts of the hook heads facing away from one another and the rear sides of the snap hooks facing one another. Each female foot part comprises at least one latch element into which the hook heads are engaged in the assembled state, thereby forming a snap connection in each case. The female foot parts are integrally connected to the upper part. An intermediate space is arranged between the rear sides of the snap hooks. Each female foot part comprises at least one securing element, each having a free end, the securing element being integrally connected to the female foot part, and the securing element protruding into the intermediate space between the rear sides of the snap hooks so that the snap hooks remain in the engaged position.
The arrangement of the at least one securing element between the snap hooks arranged in pairs allows the snap hooks to be retained in the engaged position when the plastic pallet is in the assembled state, and to not disengage from the engaged position without additional tools. The securing element results in a secure connection between the upper part and the foot parts of the skids, thus securing the attachment of skids to the upper part.
Preferably, the respective free end of the at least one securing element is tapered towards its center. The free end can be rounded or pointed towards the center. The shape of the free end of the securing element, which tapers towards the center, is particularly suitable for making it easier for the snap hooks to slide into the desired engaged position when assembling the skids along the securing element.
Preferably, the free end of the at least one securing element is symmetrically pointed. Preferably, the free end of the at least one securing element has an arrow-shaped cross-section. The symmetrically pointed end is of advantage so that each snap hook is guided along a beveled surface of the free end of the securing element when assembling the pallet. A securing element can also have a plurality of free ends, preferably arranged side by side, which are preferably tapered towards the center, more preferably symmetrically pointed.
In a preferred embodiment, the snap hook with hook head and undercut is designed to be wide in order to increase the snap connection area between the hook head and the latch element and to strengthen the snap connection. Preferably, the at least one securing element between a pair of snap hooks has two free ends which are tapered towards the center, preferably symmetrically pointed.
Each snap hook comprises a snap arm, a rear side and a hook head with undercut. The hook head has a substantially straight rear side and a front side with an undercut. In a particularly preferred embodiment, the last portion of the rear side of the snap hook in the region of the hook head leading to the tip is beveled or rounded, preferably beveled. This results in the fact that the tip of the hook head is weakened at the end of the snap hook and does not abut against the free end of the securing element when assembling the skids to the upper part. Thus, when assembling the skids to the upper part, the rear side of the hook head slides continuously along the free end of the securing element into the engaged state. As such, the snap hook has resilient properties.
The latch element has at least one recess in which the hook head of the snap hook can engage. The latch element can also have two recesses in which in each case one hook head of a pair of snap hooks is engaged. In a preferred embodiment, the latch element has an elongated shape in cross-section, with each of the recesses being arranged on the longitudinal sides of the latch element parallel to the width of the hook head. Each hook head of the snap hook engages in a recess of the latch element, and the undercut of the hook head together with the latch element forms a snap connection.
A snap connection is a positive connection and is formed by a hook head with undercut and a latch element with recess, which are designed as mating parts. The hook head engages in the recess of the latch element and the region of the undercut of the hook head engages in the latch element. Such a snap connection has the advantage that the connection is pressed together other under load, which further strengthens the connection. In addition, this snap connection has a resilient property under load.
Depending on the desired strength of the connection between the two parts of the pallet, the feet can have multiple snap connections. In one embodiment of the invention, each foot has one or more snap connection pairs, preferably one or two pairs. In one embodiment, the feet can also have four pairs of snap connections and thus eight snap connections, preferably at the outer feet of the middle skid. Due to the multiple snap connections, the strength of the feet is further increased and secured.
In one embodiment, the female foot parts of the upper part have an outer wall with ribs and the male foot parts of the skids have an inner wall with ribs. Preferably, the outer wall of the female foot parts encloses the male foot parts. The outer wall of the outer female foot part extends substantially over the entire height of the outer male foot part such that the outer male foot parts of the skids can be completely pushed into the outer female foot parts of the upper part.
The outer wall of the female foot parts encloses the male foot parts such that the male outer foot parts are fully protected in the event of an impact. The outer wall extends over the entire height of the outer female foot part, preferably substantially around the entire foot. By entire height it is understood that the outer wall of the outer female foot part extends from the upper side of the pallet to the lower side of the skid which can be placed on a support surface. Preferably, the outer wall extends around the entire foot except for a recess for a connecting piece of the skids which connects the outer male foot parts to the middle male foot part. Thus, in the assembled state of the pallet, the outer wall extends on at least three sides of the outer female foot parts from the upper side of the pallet to the lower side of the skids.
The ribs of the female foot parts and the ribs of the male foot parts preferably extend over substantially the entire height of each foot part. The ribs can have different cross-sections and can be, for example, T-shaped, angled, or rectangular in cross-section. The ribs of the female foot parts and the ribs of the male foot parts can be completely pushed into each other.
Preferably, the male foot parts of the skids have an inner wall with ribs which serve as spacers between the inner wall and the outer wall. On the one hand, these ribs also serve as a guide when assembling the skids to the upper part of the pallet and on the other hand, they form a gap between the inner wall and the outer wall, which serves as additional impact protection. In the event of an impact of the plastic pallet against an object, the ribs can bend slightly and the gap between the inner and outer walls can be reduced for a short time, which absorbs the impact.
Preferably, the plastic pallet has three skids, each having two outer male foot parts and a middle male foot part. Preferably, the plastic pallet according to the invention has three longitudinal skids. This is the case, for example, with plastic pallets of the standard size of 1200×800 mm. In this case, the outer male foot parts are inserted into the outer female foot parts and form outer feet which are provided on the short transverse side of the plastic pallet. The middle female and male foot parts, which form the middle feet, are preferably provided in the middle of the pallet transverse to the longitudinal side.
In another embodiment, the plastic pallet has more than three skids, for example five or six skids. For example, five or six skids are preferred for pallets of size 1200×1000 mm. For example, a pallet of this type is possible with five skids, of which three skids extend in one direction and two skids extend in the transverse direction along the sides of the pallet. In another embodiment, the pallet includes six skids, three longitudinal skids and three transverse skids. In this embodiment, preferably all of the outer eight feet have outer walls which extend at least on the outside of the feet, i. e., on the side which is arranged at the border of the plastic pallet, over the entire height of the outer female foot parts.
Preferably, the upper part of the plastic pallet has a flat upper side. In a preferred embodiment, the upper side has a continuous closed surface. Preferably, the lower side of the upper part has cross struts to reinforce the upper part. In another embodiment, the upper part comprises reinforcing tubes that additionally reinforce the upper part of the plastic pallet.
In a preferred embodiment, the male foot parts of a single skid can be pushed separately from the male foot parts of the other skids into the foot parts of the upper part. Thus, the three skids can be inserted individually into the upper part and the plastic pallet can be produced from four pieces. However, it is also possible that the three skids are connected to each other and consist of one piece, so that the plastic pallet can be assembled from two pieces, the upper part and a lower part provided with skids.
The foot parts of the upper part and the foot parts of the skids are preferably integrally connected to the upper part and the skid, respectively. This design, together with the snap connection, makes it possible to assemble a pallet from only two or four parts, respectively, and without the use of tools.
When joining the upper part to the skids, the male foot parts with the inner wall and the ribs are preferably pushed completely into the female foot parts with the outer wall and the ribs, so that their ribs are pushed completely into each other and are arranged parallel to each other over their entire length thereby forming the feet of the pallet, and the inner walls of the male foot part and the outer walls of the female foot part form double walls of the feet. The double walls provide increased strength to the feet such that they are more robust, withstand impacts from a forklift truck or other objects, and thus can be used for longer periods of time.
The construction of the feet allows for easy and quick assembly of the two parts of the pallet, and the snap connection allows for efficient locking without the need for a tool. If desired, the snap connection can still be opened again by using a screwdriver per snap hook to reach between the snap hook and the latch element from the lower side of the skid and push the snap hook out of the latch element. However, this is not possible without additional tools.
The arrangement of the pallet according to the invention results in the male foot parts of the skids being protected by the female foot parts of the upper part. During transport, for example on conveyor belts or during transport by forklift trucks, the short transverse sides of the pallet with longitudinal skids frequently collide with objects and must be robust against impacts. The outer feet in particular are exposed to strong forces. The male foot parts of the skids are protected by the outer wall of the outer female foot parts which extends over the entire height of the outer male foot parts. In the case of an impact of the outer feet against objects, shear forces are generated which are amplified by the weight of the transported goods on the upper side of the pallet. In the pallet according to the invention, these forces are directed into the ground via the upper side of the pallet and the female foot parts. In this case, the feet of the upper part are loaded and not the feet of the skids. As a result, the snap connection withstands even strong impacts and does not disengage even under continuous load.
The combination of a snap connection according to the invention, which remains in the engaged position due to the securing element, and the outer and inner walls of the foot parts with ribs, which serve as impact protection, leads to an extremely stable connection between the skids and the upper part and thus to increased impact resistance and longer service life compared with conventional plastic pallets.
Further advantages of the invention arise from the following description in which the invention is explained in more detail with reference to exemplary embodiments illustrated in the drawings.
In the figures:
In each of the figures, the same reference signs are used for the same elements, and explanations of a particular reference sign apply to all of the figures unless expressly stated otherwise.
Also possible is an arrangement of a plurality of securing elements with one or more free ends between a pair of snap hooks to increase the security of the snap connection.
Although various embodiments of the present invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject-matter defined in the following claims.
Number | Date | Country | Kind |
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00549/20 | May 2020 | CH | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IB2021/053569 | 4/29/2021 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2021/224732 | 11/11/2021 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
5483899 | Christie | Jan 1996 | A |
5794543 | John | Aug 1998 | A |
5934486 | Jarvis | Aug 1999 | A |
8739706 | Dubois et al. | Jun 2014 | B2 |
8950342 | Plattner | Feb 2015 | B2 |
11066210 | Ankele | Jul 2021 | B1 |
11584563 | Sostmann | Feb 2023 | B2 |
20070234933 | Donnell | Oct 2007 | A1 |
20200216219 | Shawaf | Jul 2020 | A1 |
Number | Date | Country |
---|---|---|
685549 | Aug 1995 | CH |
702628 | Aug 2011 | CH |
2733084 | Dec 2016 | EP |
2272203 | May 1994 | GB |
2421939 | Jul 2006 | GB |
H04-267735 | Sep 1992 | JP |
2005118412 | Dec 2005 | WO |
Entry |
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International Search Report mailed on Jul. 27, 2021, in connection with corresponding International Application No. PCT/IB2021/053569 (6 pp., including machine-generated English translation). |
Number | Date | Country | |
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20230166885 A1 | Jun 2023 | US |