U.S. patent number 3,603,272 [Application Number 04/785,812] was granted by the patent office on 1971-09-07 for plastic pallet and die for producing the same.
This patent grant is currently assigned to Press-Und Stanswerk Paul Craemer KG. Invention is credited to Ernst Ditges.
United States Patent |
3,603,272 |
Ditges |
September 7, 1971 |
PLASTIC PALLET AND DIE FOR PRODUCING THE SAME
Abstract
An integrally formed plastic pallet from an injection molding
die. The top portion of the pallet for carrying the load is
separated from the bottom portion through which the pallet is
supported, by spacing portions. The top and bottom portion have rib
portions arranged with recesses between them. The top and bottom
ribs are displaced from each other in conjunction with their
recesses, so that the top ribs lie above the bottom recesses,
whereas the bottom ribs lie beneath the top recesses. The recesses
are at least as wide as their respective ribs.
Inventors: |
Ditges; Ernst (Herzebrock,
Westfalen, DT) |
Assignee: |
Press-Und Stanswerk Paul Craemer
KG (Herzibrock (Westfalen), DT)
|
Family
ID: |
5677129 |
Appl.
No.: |
04/785,812 |
Filed: |
December 20, 1968 |
Foreign Application Priority Data
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Dec 20, 1967 [DT] |
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P 15 56 151.0 |
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Current U.S.
Class: |
108/57.28;
108/901 |
Current CPC
Class: |
B65D
19/0014 (20130101); B29C 45/26 (20130101); B65D
2519/00288 (20130101); B65D 2519/00318 (20130101); B65D
2519/00034 (20130101); B65D 2519/00268 (20130101); B29L
2031/7178 (20130101); B65D 2519/00333 (20130101); B65D
2519/008 (20130101); Y10S 108/901 (20130101); B65D
2519/00069 (20130101) |
Current International
Class: |
B29C
45/26 (20060101); B65D 19/00 (20060101); B65d
019/04 () |
Field of
Search: |
;108/51,52,53,58 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gay; Bobby R.
Assistant Examiner: Aschenbrenner; Peter A.
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims.
1. A plastic pallet comprising, in combination, a top portion
having a top surface for carrying the load to be applied to said
pallet; a bottom portion having a bottom surface for supporting
said pallet; spacing portions between said top portion and said
bottom portion; rib portions on said top and bottom portions
arranged with recesses between said rib portions, said rib portions
and recesses being displaced relative to each other so that the rib
portions on said top portion lie over the recesses of said bottom
portion and the rib portions of said bottom surface lie beneath the
recesses of said top portion.
2. The plastic pallet as defined in claim 1 wherein said recesses
are at least as wide as said oppositely lying rib portions.
3. The plastic pallet as defined in claim 1 wherein said plastic is
hard polyvinylchloride.
4. The plastic pallet as defined in claim 1 wherein said plastic is
polyolefin.
5. The plastic pallet as defined in claim 1 wherein said plastic is
polypropylene.
6. The plastic pallet as defined in claim 1 wherein said plastic is
low-pressure polyethylene.
7. The plastic pallet as defined in claim 1 wherein said rib
portions are U-shaped the legs of said U-shaped rib portions being
directed inward.
8. The plastic pallet as defined in claim 1 including cross
portions arranged between said rib portions on said top portion and
on said bottom portion.
9. The plastic pallet as defined in claim 8 wherein said top
portion, said bottom portion and said cross portion are of integral
construction.
10. The plastic pallet as defined in claim 1 wherein said rib
portions on said bottom portion have openings.
11. The plastic pallet as defined in claim 1, wherein said spacing
portions comprise elongated strip portions connecting respective
rib portions of said top and bottom portions and extending at least
substantially normal to the elongation of said rib portions.
12. The plastic pallet as defined in claim 11, said spacing
portions further comprising elongated reinforcing portions also
connecting respective ones of said rib portions of said top and
bottom portions but extending at least substantially normal to the
elongation of said strip portions.
Description
BACKGROUND OF THE INVENTION
Flat pallets used in materials handling have, heretofore, been
constructed of wood. These flat pallets have a top surface for
loading purposes or upon which the load is placed, and a bottom or
placement surface which is equally flat. Spacing members are
situated between these two top and bottom or placement surfaces,
and the design and combination of these elements have been
constructed, in the past, of different designs and of wood. Wooden
pallets, however, become easily damaged during severe handling and
heavy loading, and as a result such wooden pallets have only a
relatively short lifespan. Wooden pallets, in addition, are
susceptible to the effects of acids, alkalines, salts, and
humidity. Wood, furthermore, is a good nutrient for the growth of
bacteria. In view of the disadvantage from the bacterialogical
viewpoint, wooden pallets are not desirable for use in processes
involving the transfer and processing of food supplies. The same
situation and reasoning also applies to pallets made of steel,
since they are readily susceptible to rust, even though their
surfaces may be coated or plated.
In recent times, accordingly, flat pallets made of synthetic
materials such as plastic, have been considered. The plastics
preferably used for this purpose are polyethylene or polystyrene.
Such conventional pallets as used in the art, however, have the
disadvantage that they are assembled from a number of parts. As a
result, such pallet assemblies are costly to produce. The load
carrying capability and stability of the conventional plastic
pallets, furthermore, leave must to be desired.
Accordingly, it is an object of the present invention to provide a
flat plastic pallet which does not have the aforementioned
disadvantages, residing in conventional pallets. It is an object of
the present invention to provide a flat plastic pallet of high
strength and rigidity and thereby of long lifespan. It is also an
object of the present invention to provide a flat plastic pallet
which is not affected by acids, water, alkalines and salts. It is
furthermore intended, to provide pallets of the preceding character
which is not a nutrient base for bacteria growth and is thereby
adapted for use in conjunction with food supplies. In addition, it
is a specific object of the present invention to produce a plastic
pallet which may be produced in a relatively simple manner.
The objects of the present invention are achieved essentially by
constructing the top surface and the underside or placement surface
of resistor plastic material such as hard polyvinylchloride or
polyolefin such as polypropylene or low-pressure polyethylene. The
pallet has parallel ribs between which are recesses, and the ribs
and recesses of both surfaces are displaced with respect to one
another. The ribs of the top surfaces extend beyond the recesses of
the placement surface or standing surface which has ribs of at
least the width of the ribs of the upper or top surface. At the
same time, the ribs of the bottom or placement surface lie beneath
the recesses of the top surface. The ribs of both surfaces are
preferably of a U-shaped profile, and designed so that the side
legs of the U profile are directed inward. Spacing and
strengthening crossmembers or bridge members are, furthermore,
provided between the top surface and the placement surface. These
crossmembers run vertical or substantially vertical between these
surfaces. The displaced openings formed through the dies, permit
simple and thorough cleaning of the pallets.
The pallets designed in this manner, are produced, in accordance
with the present invention, through injection molding. Through the
use of a two-part construction, the pallet is made of integral or
one-piece form. The two halves of the die are arranged so that
their inner sides are spaced from each other, and form members with
plane side surfaces project outward. The form members of the two
die halves are displaced in relation to each other so that they
reach into each other without play when the die is closed. At the
outer ends of the form members, U-shaped hollow spaces remain for
the purpose of forming the plastic ribs. As a result of this
design, a grid is realized with many undercuts which was not
possible with the techniques in injection molding processes.
SUMMARY OF THE INVENTION
A flat plastic pallet of integral construction having a top portion
upon which the load to be carried by the pallet is placed. A bottom
portion through which the pallet is supported, is spaced from the
top portion through spacing portions between them. The top and
bottom portions of the pallet have ribs which are spaced from each
other with recesses between them. The ribs and recesses are
displaced relative to each other so that the ribs of the top
portion lie across the recesses of the bottom portion. Similarly,
the ribs of the bottom portion lie across the recesses of the top
portion. The recesses are at least as wide as the corresponding
ribs lying opposite the recesses. The pallet is made of plastic
material such as hard polyvinylchloride or polyolefin such as
polypropylene or low-pressure polyethylene. The ribs of the top and
bottom portions run parallel to each other.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side view of the underside of the pallet, and is taken
to one side of the axis of symmetry A--A which is a central
axis;
FIG. 2 is a sectional view taken along the line II--II in FIG.
1;
FIG. 3 is a sectional view taken along the line III--III in FIG.
1;
FIG. 4 is a sectional view taken along the line IV--IV in FIG.
1;
FIG. 5 is a partial top view of the interior side of an injection
molded portion for producing the pallet of the construction of
FIGS. 1 to 4; and
FIGS. 6 and 7 show two different sections at right angles to the
die form members used in a die for injection molding of the pallet
of FIGS. 1 to 4, respectively taken along the line VI--VI and
VII--VII of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawing, FIGS. 1 to 4 show the top surface of a
tray made of resistor or strong synthetic plastic material such as
hard polyvinylchloride or polyolefin. A plurality of parallel
profiled and U-shaped ribs 1 lie between rectangular recesses 2. At
the underside or set-on surface are, similarly, a plurality of
parallel profiled and U-shaped ribs 3 lying between rectangular
recesses 4. The ribs 1 and 3, as well as the recesses 2 and 4 of
both surfaces are displaced in relation to each other. The
arrangement is such that the ribs 1 of the top surface lie about
the recesses 4 which have a somewhat wider dimension than the ribs
1. The ribs 3, at the same time, on the set-on surface or underside
or placement surface are, at the same time, beneath the recesses 2
which are similarly wider in width, to some extent, than the ribs
3. These dimensional relationships and arrangement may be seen by
referring to FIGS. 3 and 4.
Between the ribs 1 and 3, and at right angle to them, are vertical
flat bridges 5 which serve as spacers. In addition, flat bridges 6
are provided between legs of the U-shaped ribs 1 and 3 which lie
substantially vertically opposite to each other outside of the
external flat bridges 5. These flat bridges 6 also serve as
spacers, and when functioning together with the vertical flat
spacers 5 of the pallet, an exceptionally large amount of stability
is realized.
The top surface, the placement surface and the flat bridges 5 and 6
are of integral construction and produced through injection molding
as a one-piece unit, in accordance with the present invention.
The top surface has a frame 7 which extends beyond all of the sides
of the placement surface. This frame 7 has a U-shaped profile
similar to the ribs 1 and 3. As shown in FIGS. 3 and 4, angle or U
structural members 8 may be injection molded into this frame. These
structural members 8 serve to impart additional stability to the
tray or pallet. It is also possible to injection mold similar such
structural members into the ribs 1 and/or 3. These structural
members may be made of iron or other metallic substance.
Holes 9 are provided in the ribs 3 of the placement surface. These
holes prevent the accumulation of water or other fluids in the
upper open profiles of these ribs.
The placement surface also has four large rectangular recesses 10
which are intended for receiving the running rollers of forklift
trucks. When the fork thereof is in lowered position and inserted
beneath the pallets to such an extent that the pair of rollers
immediately rearwardly of the fork will enter into a corresponding
pair of the recesses 10. The legs 3a of the U-shaped ribs 3
bordering the recesses 10 are maintained somewhat lower and have
upper inclined edges 36, so that driving in and out of the pallets
by forklift trucks is simplified. The dies for producing the
pallets with the structure described above, consists of two parts
11 and 12, as shown in FIGS. 6 and 7. Both die parts have form
members 13 or 14 with plane side surfaces at their inner surfaces
and spaced from each other, while at the same time projecting to
the exterior. The bridge members 13 and 14 are displaced in
relation to each other so that when the die is closed, the bridge
members reach into each other without play. Hollow spaces 15 and 16
only remain for the purpose of forming the plastic ribs 1 and 3.
These hollow spaces 15 and 16 remain at the outer ends of reduced
cross section of the members 13 and 14, and are U-shaped.
Between neighboring front surfaces of the members 13 and 14, free
gaps 17 are provided for forming the vertical plastic bridges 5
which are at right angle to the ribs 1 and 3. These bridging
members such as the member 5, for example, may also be designated
as crossmembers or flange members. A number of members 13 and 14
lying outside of the outer gap 17, furthermore, are designed so
that a free gap 18 remains for the purpose of forming the plastic
crossmember 6, after the die parts 11 and 12 are brought together.
The members 13 have, moreover, pins 19 on their outer surfaces, for
the purpose of forming holes 9 in the plastic ribs 3.
The recesses 10 serving the purpose of receiving the running rolls
of the forklift truck are rectangular, and are formed through the
rectangular forming member 20 in the die part 12.
The flat pallets made of synthetic or plastic material, in
accordance with the present invention, are preferably produced with
dimensions of 1000 .times.1200 mm., 800 .times.1200 mm., and 800
.times.1000 mm. By using identical die elements, these sizes of
pallets can be produced in integral or one-piece form through
injection molding techniques.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of constructions differing from the types described
above.
While the invention has been illustrated and described as embodied
in plastic pallets and their dies, it is not intended to be limited
to the details shown, since various modifications and structural
changes may be made without departing in any way from the spirit of
the present invention .
* * * * *