JPH0639817A - Article molding method - Google Patents

Abstract

PURPOSE: To form an article having a main surface and a displaced non-plane by a method in which a layered mat of felt formed by mixing a resin particle board binder with wood particles is deposited in a mold, the mold is closed, and a single structure is formed by applying beat and pressure. CONSTITUTION: Flaky wood particles 1.25-6 inch in average length, 0.005-0.075 inch in average thickness, 3 inch or below in average breadth, and shorter than the average length are prepared and mixed with a resin particle board binder, and a layered mat 30 of felt formed from the mixture is deposited on one open part 36 of a mold 32 which decides a mold chamber having the shape of an article. the wood particles in each layer of the mat 30 are laid flat on a main surface, the mold 32 is closed, enough heat and pressure are applied to the mat 30, the mat 30 is compressed to have the desired shape and size of an article, the wood particles are bonded together, and the article having the main surface of a single structure and at least one non-plane displaced from the main surface is molded.

Description

Detailed Description of the Invention

The present invention relates to articles molded from flake-like wood particles, and more particularly to such articles having non-planar portions, such as pallets for handling materials. Considerable efforts have been made to develop techniques for molding articles containing non-planar parts from cheap residues and excess wood. One area of particular interest for utilizing such wood is that of manufacturing material handling pallets that have at least the same strength, durability and other desirable properties as standard pallets constructed from sawn wood.

Finely ground wood is mixed with a suitable resinous binder, such as a synthetic thermosetting resin, the mixture is formed into a multilayer mat and the mat is then compressed between heated slabs, and It is well known to make flat or practically flat structural boards, or so-called particle boards, from finely ground wood by binding wood particles together. This type of method is described in US Pat. Nos. 3,164,511 and 3,391,
233 and 3,940,230.

The molding of pallets and other articles containing non-planar portions presents problems that have little or no bearing on the manufacture of flat or substantially flat particle boards. For example, one that occurs in pallet molding
One difficulty is the need to draw multiple hollow legs with acceptable crush strength from a substantially flat mat of wood particles without adversely affecting the strength of the deck member or legs. It is sex. After all, the aforementioned type of method for making granular particleboard has not previously been used to make pallets or other similar articles from wood particles.

US Pat. Nos. 3,104,085 and 3,35
In one prior art method of forming pallets from wood particles, illustrated by 9,929 and 3,611,952, wood fibers are made into a pulp slurry. The pulp slurry also typically contains a resinous binder or other suitable binder. This slurry is introduced into a mold in which most of the water is removed, such as by compression, application of vacuum or positive pressure. Transfer this moist molded pallet to a heated mold and dry it under high pressure and temperature conditions to facilitate the removal of water and cure it when a binder is included. To do. When the binder is not included in the slurry, the dried pallet is usually dipped in a resin-containing solution to be reinforced and waterproof. This prior art method involves several costly processing steps, and the pallets produced thereby do not have acceptable strength properties or durability for many applications.

Another prior art method of forming pallets from wood particles, promoted in the United States under the trademark "WERZALIT" and exemplified by US Pat. Nos. 3,146,285 and 3,354,248. In, the finely ground wood particles and the thermosetting resinous binder are introduced into a cold press to form a preform that has approximately the final size and shape of the pallet, while the binder is partially cured. , Or does not cure. The preform is transferred to a heated press or mold in which it is pressed at elevated temperature to its final size and shape to fully cure the binder. This method is such that the starting material must be comminuted, the amount of binder required to bond together the relatively small wood particles, the capital investment for different presses,
And, because of the operating costs associated with multiple processing steps, they are relatively expensive.

A primary object of the present invention is a material handling pallet having a main body and a non-planar portion displaced from the main body, the main body and non-planar portion being formed as an integral unit from low cost wood. Is to provide an article, such as.

Another object of the present invention is to provide a pallet molded from low cost wood and having strength and handling properties that are at least comparable to standard pallets made from barbed lumber.

Another object of the invention is to provide a simplified method of molding such pallets and other articles having non-planar portions from low cost wood particles.

Yet another object of the present invention is to provide such a method which does not require shaping of the preform prior to shaping to final dimensions and does not require finely ground wood particles. is there.

Other objects, aspects and benefits of the present invention will be apparent to those of ordinary skill in the art from the following detailed description, drawings and claims.

The pallet provided by the present invention comprises a deck member having a main plane and a plurality of hollow leg members integrally projecting from the deck member, each leg member being spaced from the deck member. It has a bottom wall and a side wall located, and the side wall is inclined outward from the bottom wall toward the deck member. The deck and leg members are molded as an integral unit from a resinous particle board binder, such as a layered mixture of thermosetting resin, organic polyisocyanate or mixtures thereof and flake-like wood particles. The average length is about 1.25 to about 6 inches (about 3.
18 to about 15.24 cm) with an average thickness of about 0.00
5 to about 0.075 inch (about 0.013 to about 0.191)
cm) and an average width of about 3 inches (about 7.62c)
m) or less and shorter than the average length. Each layer of wood particles forms at least a deck member that lies substantially flat in a plane that is generally parallel to a major plane in which the wood particles are randomly oriented.

The sidewalls of the leg members can extend at an angle of less than or equal to about 78 ° with respect to the major plane of the deck member, and are about 70-110%, preferably about 80-85% of the average thickness of the deck member. It can have an average thickness.

The pallet contains about 2 to about 15% by weight binder, and optionally about 0.5 to about 2% by weight wax, based on the dry weight of the wood flakes, to provide waterproofness. Can be given. Organic polyisocyanates, alone and in combination with urea-formaldehyde,
The preferred binder.

In a preferred method, the wood flakes are mixed with a resinous particleboard binder and the resulting mixture or composition is an open system containing two separable parts defining a mold chamber having the shape of a pallet. Deposit on one part of the mold or press as a loosely felted layered mat, close the mold,
Then, pressure is applied to the mat to compress it to substantially the desired shape and size of the pallet and bond the wood flakes together.

In one embodiment, the mat of substantially uniform thickness is formed outside the mold, and according to this method,
The flakes in each layer lie substantially flat and are randomly oriented, and the mat is placed between the M and F dies of the mold. In another embodiment, the mat is formed external to the mold as described in the previous section, and a mound of the composition is added on the mat at a location corresponding to the leg forming cavity of the F die.

In another embodiment, the leg forming cavities of the F die are first substantially filled with the composition and the mat is then placed between the M die and the F die.

In yet another embodiment, the mat is formed directly on the F-die or a distant backing plate having a shape conforming to the F-die and subsequently placed on the F-die. This technique and the techniques described in the two previous sections are particularly advantageous for molding leg members having a length or depth of up to about 5 inches (12.7 cm) or more.

The invention broadly includes an article, particularly a support member, comprising a main body having a major surface and a non-planar portion displaced from the major surface, both of which are molded as an integral unit from wood flakes. Regarding The present invention has particular application to, and will be described with, material handling pallets.

A pallet 10 is illustrated in FIGS. 1 and 2. The pallet 10 includes a generally flat rectangular deck member 12 having a substantially uniform wall thickness and a flat top surface 14 which serves as a support plane. A plurality (eg, 9) acting as support pads for the pallet.
The hollow leg member 16 of (1) projects downward from the deck member 12. In the particular structure illustrated, each leg member 1
6 (FIG. 2) includes a bottom wall 18 having a flat bottom plane 20 and two opposing pairs of flat sidewalls 22 and 24.
The bottom surface 20 of the bottom wall 18 is spaced from the lower surface of the deck member 12 at a distance sufficient to allow the forklift teeth underneath the deck member to bite into it.

The deck member 12 and leg members 16 are molded as a unitary unit from a mixture of suitable resinous particleboard binder and flake-like wood particles, as described below. The sidewalls 22 and 24 of the leg member 16 are sloping, i.e., tapered, to facilitate molding, and also allow for the fitting of several pallets to minimize the space required for transport and storage. . In the particular construction illustrated, the sidewalls 22 and 24 are substantially flat, and the leg members 16 have the general shape of an inverted frustoconical hollow pyramid. Leg members 16 if desired
Can be shaped to have any other suitable cross-sectional shape, such as the shape of a hollow cone with an inverted truncated cone shape. FIG. 3 diagrammatically illustrates the various steps of the method of the present invention for making a pallet 10 from cheap residual wood and surplus wood. This method is broadly defined by crushing small logs, branches or rough pulpwood into flake-like particles, drying the wood flakes to a predetermined moisture content and classifying the dried flakes to a predetermined size. Wood particles are obtained and a predetermined amount of a suitable resinous particleboard binder, and optionally a liquid wax composition, is blended with the dried, sized flakes to yield the binder, wax and wood flakes. An open mold comprising a mixture or composition formed into a loosely felted layered mat (single or multi-layer), the mat including separable M and F dies defining a mold chamber having the desired shape of the pallet. Place in a mold or press, close the mold, and apply sufficient pressure to the mat to make it substantially the desired shape and size of the pallet. To, and the periphery of the pallet is trimmed to the desired final dimensions, etc. This power.

The wood flakes used can be made from various species of suitable hardwood and softwood used in making particleboard. Typical examples of suitable wood are poplar,
Maple, oak, balsam firs, pine, too Himalayan, scallops, hemlock, bogus acacia, beech, hippo and mixtures thereof.

Suitable wood flakes can be manufactured by a variety of conventional techniques. In a particular method, wood flakes are produced by one of two different techniques. In the technique illustrated in the upper left part of FIG. 3, pulp grade logs, or so-called roundwood
Flakes d) in one operation using conventional round flakers. In the technique illustrated in the upper right part of FIG. 3, logs, wood cuttings residues or whole wood are first cleaned in conventional equipment, for example in a spiral grinding shearer as disclosed in US Pat. No. 4,053,004. 6 inches (5.08-1
A finger ring with a length of about 5.24 cm
erling) and flake the finger ring with a regular ring-shaped flaker.

The round flakes generally produce a higher quality, stronger pallet as the length and thickness can be adjusted more precisely. Also, pills tend to be somewhat flattening, which facilitates efficient compounding and logs can be peeled before flaking, which can result in undesirable fines during flake operations and handling. The amount decreases. Acceptable flakes can be produced by ring flaking the finger ring, and this technique can easily accept poor form of wood,
This allows for more complete utilization of certain types of residual and surplus wood.

Regardless of the particular technique used to produce the flakes, the distribution of flake size, particularly length and thickness, is very important. Wood flake is about 1.25 to about 6
An average length of inches (about 3.18 to about 15.24 cm) and about 0.005 to about 0.075 inches (about 0.013).
Should have an average thickness of about 0.191 cm. In any given batch, a portion of the flakes was 1.
Can be shorter than 25 inches (3.18 cm),
And a portion can be longer than 6 inches (15.24 cm), but only if the total average length is within the above range. The same applies to thickness.

The presence of a major amount of flakes having a length less than about 1.25 inches (about 3.18 cm) pulls the mat when the leg members are drawn from the mat during the molding process. Tends to separate. This undesired condition becomes particularly apparent at the corner joint between the leg member and the deck member, as described in detail below. The presence of some fines in the mat produces a smooth surface, thus the majority of the wood flakes, preferably at least 75%, are longer than 1.125 inches (2.858 cm).
And an average length of at least 1.25 inches (3.18 cm)
As long as it is, it may be desirable for some applications.

A substantial amount of flakes is 6 inches (15.2).
Longer than 4 cm), the flakes tend to interlock or felt during handling before forming the mat and complicating the leg forming.
For example, such interlocking can prevent proper coating of the flakes with a binder during the compounding process, resulting in improper flake bonding during molding. The average length of the wood flakes is preferably from about 2 to about 3 inches (about 5.08 to about 7.62 cm).

Substantial amounts of flakes having a thickness of less than about 0.005 inch (about 0.013 cm) should be avoided because of the excessive amount of binder needed to obtain a proper bond. . On the other hand, flakes having a thickness greater than about 0.075 inches are relatively stiff and tend to overlap each other at a slight angle when formed into a mat. Eventually, excessively high mold pressure is required to bring the flakes into intimate contact with one another as desired. For flakes having a thickness falling within the above range, thin flakes produce a smooth surface, while thick flakes require less binder. These two factors balance against each other when choosing the best average thickness for any particular application. The average thickness of the flakes is preferably about 0.015 to about 0.25 inches (about 0.038 to about 0.635 cm), and most preferably about 0.020 inches (about 0.051 cm).

The flake width is not very important. The flakes should be wide to ensure that they lie substantially flat when felting during mat formation. The average width should generally be less than or equal to about 3 inches and less than the average length. For best results,
Most of the flakes are about 1/16 to about 3 inches (about 0.1
It should have a width of 59 to about 7.62 cm).

The flake thickness can be adjusted primarily by blades placed on the flaker. The length and width of the flakes can likewise be highly adjusted by the flaking operation. For example, when producing flakes by ring flaking a finger ring, the maximum length is generally set by the length of the finger ring. Other factors, such as the moisture content of wood and the amount of skin on wood, affect the amount of fines produced during flaking. Dried wood is more brittle and tends to produce higher amounts of fines. During peeling and subsequent handling, hides are more likely to be broken into fines than wood during flaking and subsequent handling.

The size of the flakes can be highly adjusted during the flaking operation as described above, but usually some sort of classification is performed to remove unwanted particles, both too small and too large. It is necessary to ensure that the average length, thickness and width of the flakes are within the desired range. When using flaking of pills, it is usually necessary to use both screen and air classification to properly remove both undersized and oversized particles, while finger ring flakes are usually screen classified. It can be appropriately sized by only.

Flakes from raw wood may contain up to 90% moisture. The moisture content of this mat must be substantially low for molding, as described below. Also, moist flakes tend to stick together, complicating pre-blending classification and handling. Therefore, the flakes are preferably dried in a conventional dryer, such as a tunnel dryer, prior to classification to the desired moisture content for the compounding process. The flakes are usually dried to about 6% by weight or less, preferably about 2 to about 5% by weight, based on the dry weight of the flakes. If desired, the flakes can be dried to a moisture content on the order of 10 to 25% by weight prior to classification and then to a desired moisture content for post-classification formulation. This two-step drying can reduce the total energy requirement for drying flakes made from raw wood. This is because the drying of the particles, which must be removed during the classification, is unnecessary in the drying in the second stage.

A known amount of dried and classified flakes is introduced into a conventional compounder, such as a paddle-type batch compounder, in which the amount of resinous particle binder, optionally wax and the like, previously determined. Add the additives of 1. while tumbling or stirring the flakes in the compounder. Suitable binders include those used in the manufacture of particleboard and similar pressed textiles and are thus referred to herein as "resinous particleboard binders". Representative examples of suitable conjugates are: thermosetting resins, such as fetor-formaldehyde, resoncinol-formaldehyde, melamine-formaldehyde, urea-formaldehyde,
Urea-furfural and condensed furfuryl alcohol resins, and organic polyisocyanates, either alone or in combination with urea-formaldehyde or melamine-formaldehyde resins. Particularly suitable polyisocyanates are those which contain at least two active isocyanate groups per molecule, the materials of which are: diphenylmethane diisocyanate, m
-Phenylene diisocyanate, p-phenylene diisocyanate, chlorophenylene diisocyanate, toluene diisocyanate, toluent isocyanate,
Triphenylmethene triisocyanate, diphenyl ether-2,4,4'-triisocyanate and polyphenyl polyisocyanates, especially diphenylmethane-4,4'-diisocyanate.

The particular type of binder used depends primarily on the intended use of the pallet. For example, pallets with urea-formaldehyde resins have sufficient moisture durability for many applications with minimal exposure to moisture, but generally cannot withstand extended outdoor exposure and are reusable. Sex is very limited. Phenol-formaldehyde and melamine-formaldehyde resins provide excellent moisture resistance, but require substantially long cure times. Polyisocyanates, even in small amounts, are urea-formaldehyde or phenol-
It offers greater strength and moisture resistance than formaldehyde resins, and the resulting pallets can be reused for extended numbers of cycles. Polyisocyanates cure in about the same time as urea-formaldehyde resins. However, polyisocyanates are expensive and tend to stick to metal parts, necessitating the use of mold release agents. These factors balance each other when choosing to use a particular binder.

Binder systems containing both urea-formaldehyde resin and polyisocyanate at a solids weight ratio of about 4: 1 to about 1: 1 are less expensive than polyisocyanate alone, but urea-formaldehyde or phenol-. It provides superior strength properties and moisture resistance over binders obtained from formaldehyde resins alone, and the pallet is reusable, which is beneficial for many applications.

The amount of binder added to the flakes during the compounding process depends primarily on the particular binder used, the flake size, moisture and type, and the desired properties of the pallet. Generally, the amount of binder added to the flakes is about 2 to about 15% by weight, preferably about 4 to about 10% by weight, as solids, based on the dry weight of the flakes. When polyisocyanates are used alone or in combination with urea-formaldehyde resins, the amounts can be further towards the lower end of these ranges.

The binder can be mixed with the flakes in dry or liquid form. For best coverage of the flakes, the binder is preferably applied by spraying drops of liquid binder onto the flakes as they are tumbled or agitated in the blender. When using polyisocyanates, a conventional mold release agent is preferably applied to the surface of the die or formed mat prior to pressing. In order to improve the water resistance of the pallet, a conventional liquid wax emulsion is preferably likewise sprayed onto the flakes during the compounding process. The amount of wax added is generally about 0. 0 as a solid based on the dryness importance of the flakes.
5 to about 2% by weight. Other additives, such as colorants, flame retardants, insecticides, fungicides, etc., are added during the compounding process.
It can also be added to flakes. The binder, wax and other additives can be added separately in any order or in bonded form.

The moist mixture or composition of binders, waxes and flakes from the compounding process is formed into a loosely felted single or multi-layered mat which is compressed into pallets. The moisture content of the flakes should be adjusted within certain limits to ensure proper coating with a blender during the compounding process and to increase binder hardening and flake deformation during molding.

The presence of moisture in the flakes promotes the incorporation of the flakes into intimate contact with each other and forms the leg members, and enhances uniform heat transfer throughout the mat during the molding process, thereby providing a uniform heat transfer. To ensure proper curing. However, excessive amounts of water tend to decompose some binders, especially urea-formaldehyde resins, and generate water vapor which can cause blistering. On the other hand, if the flakes are too dry, the flakes will contain excessive amounts of binder, leaving insufficient amount of binder on the surface for good bonding, and the surface tends to harden. Yes,
This prevents the desired chemical reaction between the binder and the cellulose in the wood. The latter situation is especially true for polyisocyanate binders.

Generally, the moisture content of the composition after formulation is about 5 to 5 including the original moisture of the flakes and the moisture added during formulation with the binder, wax and other additives.
It should be about 25% by weight, preferably about 8 to about 12% by weight. Generally, higher moisture levels within these ranges can be used for the polyisocyanate binder. This is because the polyisocyanate binder does not produce a bond product when it reacts with cellulose in wood.

The composition is formed into a rectangular, generally flat, loosely felted mat, preferably a multilayer mat, corresponding to the outer dimensions of the pallet. US Patent 3,3
Mats can be formed using conventional dispensing systems similar to those disclosed in Nos. 91,223 and 3,824,058. Generally, such a distribution system
It includes an endless belt or plate-like carriage supported on a conveyor and one or more (eg, three) hoppers spaced apart along the belt in the direction of travel for receiving the composition. When forming a multi-layer mat according to the preferred embodiment, a plurality of hoppers are typically used, each hopper having a dispensing head extending across the width of the carriage, the heads comprising the composition as the carriage moves beneath them. Sequentially depositing separate layers of.

To produce a pallet with the desired strength properties, the mat should have a substantially uniform thickness and the flakes should lie substantially in a horizontal plane parallel to the surface of the carriage. It should lie down and be randomly oriented with respect to each other in that plane. The thickness uniformity of the mat can be adjusted by depositing two or more layers of the composition on the carriage and metering the composition flow from the forming head.

The desired irregular orientation of the flakes space the forming head over the carriage, thus allowing the flakes to be about 1 to about 3 inches (about 2.54 to about 7.6) into the carriage.
It can be increased by having to fall at a distance of 2 cm). As the flat flakes fall from that height, they tend to fall in a spiral downwards and land generally flat in an irregular pattern. Wider flakes within the aforementioned range enhance this effect. A scraper or similar device spaced above the carriage can be used to ensure a uniform thickness or depth of the mat. However, such means usually tend to align the top layer of the flakes, ie eliminate the desired irregularities. Therefore, the thickness of the mat is preferably adjusted by closely metering the flow of composition from the forming head.

The thickness of the mat used depends on the size and shape of the wood flakes, the particular technique of forming the mat, the desired thickness and density of the deck and leg members of the pallet, the shape of the pallet (particularly of the leg members). Size and shape), and the molding pressure used, will vary. For example, if the pallet is 0.5 inches thick (1.2
7 cm deck members and 45 lbs / ft3 (0.
When having a density of 72 g / cm ³ , mats typically have about 3 inches when using round flakes.
m), and when using flakes made by ring flaking of finger rings will have a thickness of about 4 inches (about 10.16 cm). Of all these variables, the final density of the pallet is the main factor in determining the mat thickness.

Referring to FIG. 4, the mat 30 is compressed in a heated press or mold 32. The mold 32 includes a moveable M die 34 and a stationary F die 36, which together define a mold chamber having the shape of a pallet. F-die 36 includes a plurality of cavities 40 (one shown), each cavity defining an exterior of leg member 16, and M-die 34 having a plurality of corresponding protrusions 42 (1).
Each of which is shown), and each protrusion defines the interior of the leg member 16.

The mat 30 is removed from the forming carriage and deposited on the F die 36 as illustrated. When the M die 34 is closed, a portion of the mat 30 is draw molded, i.e., drawn down into the cavity 40 of the F die,
The leg member 16 is formed. This contrasts with the material flowing into the mold when using a plastic material and a finely divided fibrous molding composition. Thus, the leg member 16
The corner joint between the deck member 12 and the deck member 12 is particularly susceptible to structural weakening resulting from the tendency of the flakes to be pulled apart during the molding operation.

The method of the present invention uses wood flakes having a size within the ranges described above for the most part, and mat 30
This tendency is minimized by forming a layer of wood flakes which is substantially flat and irregularly oriented. Instead of pulling the corners of the corner apart to separate them, a number of flakes bend or deform somewhat around the corners, thereby providing a bond with substantial structural integrity.

Due to this draw or draw action on the mat during molding, there are some practical restrictions on the shape of the pallet. Referring to FIG. 2, the inclination of the sidewalls 22 and 24 with respect to the main horizontal plane of the deck member 16, as indicated by angle A, should not exceed about 78 °. Deck member 12
If it is desired to have a relatively tight corner between the bottom of the foot and the leg member 16, the outer radius labeled R ₁ should be substantially larger than the inner radius labeled R ₂ . Large leg members (eg, 7 inches x 9 inches (17.78 cm x 2)
2.86 cm)] is generally a small leg member [eg, 5 inches (12.7 cm)] when the sidewalls have the same slope.
It is easier to mold than the diameter. Generally, the slope and depth are smaller for smaller leg members. Side wall 22 and 2 of the leg member
4 generally has a thickness that is 70-110% of the thickness of the deck member, preferably about 80-85%. The thickness of the bottom wall can be about 60-100% of the thickness of the deck member.

The leg members are about 6 inches (about 15.2) from each other.
4 cm). Even at this distance, requiring an additional amount of flakes to compensate for the amount of flakes drawn or drawn into the F die cavity during the forming operation, especially when forming deeper or longer leg members. There is. For example, as shown in FIG. 4, the mat is formed outside the mold, and the M die and F
Approximately 1.75 inches (about 4.45 cm) when manufacturing a 40 inch x 48 inch (101.6 cm x 121.9 cm) pallet with 9 leg members placed between the dies.
A leg member having a depth of up to (shown as dimension D in FIG. 2) can be conveniently drawn from such a mat.

FIGS. 5-7 illustrate another technique for depositing flakes in a mold so that longer or deeper leg members can be drawn. In the technique shown in FIG. 5, the cavity 40 of the F die 36 is first substantially filled with the composition 44 and formed on the outside of the mold, similar to the mat 30 in FIG. 4, of a substantially uniform thickness. The loosely felted mat 46 is deposited on the F die 36, over the filled cavities and then the mold is closed.

In the technique illustrated in FIG. 6, a loosely felted mat 48 of substantially uniform thickness is formed on the outside of the mold, similar to mat 30 in FIG. 4, and is deep drawn. Mound of additional composition required (mo
und) 50 is deposited on top of the mat 48 at a location corresponding to the location of the F die cavity 40, which mat 48 is then placed in the mold. The technique illustrated in FIGS. 5 and 6 has been successfully used to form pallets with leg members up to 5 inches (12.7 cm) deep and sidewall slopes of 56 ° to 77 °. .

In the technique illustrated in FIG. 7, the mat 52 is loosely felt directly onto the F die 36 by passing it under the forming head (not shown).
Alternatively, the mat can be deposited on a remote caul plate or pan that conforms to the F die, which is subsequently placed on the F die. The additional composition required for deep draw forming is provided by the tendency of the F-die cavity 40 or caul plate to absorb excess composition during the felting operation.

Molding temperatures, pressures and times vary widely depending on the thickness and desired density of the pallet, the size and type of wood flakes, the moisture content of the flakes, and the type of binder used. The temperature used is sufficient to, within a reasonable time, not carbonize the wood, at least cure the binder and drive water out of the mat. Generally from ambient temperature to about 450 ° F (about 232 ° C)
Molding temperatures in the range of up to can be used. Temperatures above about 450 ° F. (about 232 ° C.) can carbonize wood.
When using a binder system comprising a urea-formaldehyde resin and a polyisocyanate, about 250 to about 375 ° F.
Molding temperatures of from about 121 to about 191 ° C are preferred, while phenolic-formaldehyde resin binders have molding temperatures of from about 300 to about 425 ° F (149 to about 218 ° C).

The molding pressure used is such that the wood flakes are intimately close to each other, without breaking them, until the lignin begins to seep out, breaking the fibers and degrading the structural integrity.
It should be sufficient to press into contact.
Molding pressure applied to the net die area is typically about 30
0 to about 700 psi (about 21.1 to about 49.2 kg / cm ³ )
Is.

The molding or pressing cycle time depends on the pallet having suitable structural integrity for handling.
Sufficient to at least partially cure the binder.
The press cycle is typically about 2 to about 10 minutes.
However, shorter or longer times can be used when using pressure-curing binders, or when more complete cure of some thermosetting binders is desired.

After removing the pallet from the mold, the edges are trimmed to the desired final dimensions, for example 40 inches x 48 inches (101.6 cm x 121.9 cm). The molding apparatus can include means for providing built-in trimming during pressing. A typical pallet, when using a thermosetting resin type binder, is approximately 9% by weight.
Resin, about 1% by weight wax and about 92% by weight wood. The resin content is typically about 5% by weight when using polyisocyanate resin,
And when the binder is a combination of urea-formaldehyde resin and polyisocyanate, it is about 7% by weight.

It is believed that those of ordinary skill in the art, with the aid of the foregoing description, will be able to make full use of the present invention without undue effort. Further explanation will be given by the following examples. These examples
It should not be considered as limiting the invention.

EXAMPLE I Poplar round flakes [average length 1.75 inches (4.
45 cm), average thickness 0.21 inch (0.53 cm)],
9 wt% urea-formaldehyde resin and / wt%
Various strength tests were performed on sample pallets made in accordance with the present invention using the waxes of. The sample pallet has an average density of 39 pounds / cubic foot (0.63 kg).
/ Cm ³ ). 300 ~ 350psi (21.1 ~ 2
Pressure of 4.6 kg / cm ³ ) 300-325 ° F (149
A temperature of ˜163 ° C. and a pressing time of 4.5-7 minutes was used for molding.

The leg crush test is based on Tinius Olson (Tin).
ius olson) tester with 16 legs in the dry state and 16 legs soaked for 24 hours and then dried to constant weight at 15% relative humidity and 70 ° F (21 ° C). did. The average crush strength for maximum load is 3.548 lbs (1.611 kg) for the first group and 2.7 for the second group.
It was 27 pounds (1.238 kg). Based on these test results, a nine-leg pallet could theoretically reach up to 24.543 lbs (1
1.143 kg) can be supported.

The strength of the deck was 3 inches × 14 inches (7.62 cm × 35.
56 cm) sample was determined by testing. The average crush factor is 2.435 pounds per square inch (17
It was 1.2 kg / cm ³ ). The other samples were soaked for 48 hours and tested when wetted to have an average crush factor of 1000 pounds per square inch (70.3 kg / cm ³ ).
Met.

Example II Pallets with legs of different sizes and shapes were molded from various flakes and binders. The leg sections from these pallets were tested for crush strength. The legs of these pallets were fitted with 50% relative humidity and 70 ° F (2
Conditioned at 1 ° C and subjected to a compressive load perpendicular to the pallet deck surface at a maximum bending of 0.5 inch (1.27 cm) at a load rate of 0.10 inch / minute (0.0254 cm / minute). Up to. The results from these tests are summarized in Table 1.

[0061]

[Table 1]

From these test results, all leg parts were found to be in accordance with ASTM Static Load Capacity.
Minimum requirements for Test (static load capacity test), ie,
The center leg of a 2000 lb capacity pallet must support 15% of 9750 lbs (4426 kg), or 1462 lbs (663.7 kg). It turns out that the requirement is far exceeded.

From the above description, those skilled in the art can easily confirm the essential features of the present invention, and various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention. And can be adapted to the requirements.

[Brief description of drawings]

FIG. 1 is a perspective view of a pallet having various features of the present invention.

2 is a cross-sectional view generally taken along line 2-2 of FIG.

FIG. 3 is a schematic flow diagram illustrating various steps of a preferred method of forming pellets of the present invention from residual and surplus wood.

FIG. 4 is a simplified schematic side view of a mold or press illustrating various techniques for depositing a mat of wood flakes on an F die prior to mold closure.

FIG. 5 is a simplified schematic side view of a mold or press illustrating various techniques for depositing a mat of wood flakes on an F die prior to mold closure.

FIG. 6 is a simplified schematic side view of a mold or press illustrating various techniques for depositing a mat of wood flakes on an F die prior to mold closure.

FIG. 7 is a simplified schematic side view of a mold or press illustrating various techniques for depositing a mat of wood flakes on an F die prior to mold closure.

[Explanation of symbols]

10: pallet, 12: deck member, 14: upper surface, 1
6: Hollow leg member, 18: Bottom wall, 20: Bottom surface, 22:
Side wall, 24: side wall, 30: matte, 32: press or mold, 34: movable M die, 36: stationary F die, 4
0: cavity, 42: protrusion, 44: composition, 46: mat, 48: mat, 50: mound, 52: mat.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tauno Bee Kilpera Box 41, Atlantic Mine, Michigan, USA 41 (72) Inventor Anders Eland, 1108, Carrage Avenue, Houghton, Michigan, USA ( 72) Inventor James F. Hamilton 1307 Ruby Avenue, Houghton, Michigan, USA

Claims (18)

[Claims] 1. (a) An average length of 1.25 to 6 inches (3.18 to 15.24 cm) and an average thickness of 0.0.
05-0.075 inch (0.013-0.191 cm)
And flake-like wood particles having an average width of 3 inches (7.62 cm) or less and shorter than the average length, (b) mixing the resinous particleboard binder with the wood particles, c) depositing a loosely felted layered mat formed from the mixture on one open part of the mold containing two separate parts defining a mold chamber having the shape of the article, in each layer of the mat Wood particles lying substantially flat in a plane generally parallel to the major plane,
And (d) closing the mold and applying sufficient heat and pressure to the mat to compress it into the desired shape and size of the article and bond the wood particles together to form a unitary structure. A method of forming an article having a major surface and at least one non-planar portion displaced from the major surface, the method comprising: forming. 2. The article is a pallet having a deck member including a main plane and a non-planar portion formed of a plurality of hollow leg members integrally protruding from the deck member, each leg member being the deck member. A bottom wall and a side wall spaced apart from the bottom wall, the side wall integrally connecting the bottom wall to the deck member and sloping outwardly from the deck member toward the bottom wall. The method according to claim 1, wherein 3. The mold has an M die and an F die; and step (c) forms the mat having a substantially uniform thickness outside the die, and the mat is an M die. The method of claim 1, further comprising: disposing between an F die and an F die. 4. The article has a base including a principal plane and a non-planar portion formed of a hollow member integrally protruding from the base; the mold has an M die and an F die, and each hollow member. And step (c) forms the mat having a substantially uniform thickness outside of the mold, and the mound of the mixture is placed on the mat over the cavity of each F die. The method of claim 1 including depositing at a location corresponding to the location and placing the mat between the M die and the F die with the mound generally aligned with the cavity of the respective F die. 5. The article has a base including a main plane, and a non-planar portion formed of a hollow member integrally protruding from the base; the mold has an M die and an F die, and each hollow member. And (c) substantially filling the cavities of each F die with the mixture to form the mat having a substantially uniform thickness outside the mold. And then placing the mat between the M die and the F die. 6. The article has a base including a main plane and a non-planar portion formed of a hollow member integrally protruding from the base; the mold has an M die and an F die, and each hollow member. Forming a mat having a substantially uniform thickness on a distant caul plate having a shape corresponding to the F die and forming the mat with the F die. The method of claim 1, comprising placing on top of. 7. The wood particles have an average thickness of 0.015 to 0.
The method of claim 1, which is 025 inches (0.038-0.064 cm). 8. The method of claim 1 in which the wood particles have an average thickness of 2-3 inches (5.08-7.62 cm). 9. The method of claim 1 wherein the majority of the wood particles are 1/16 to 3 inches (0.159 to 7.62 cm) wide. 10. The pressure applied to the mat in step (d) is 300 to 700 psi (21.1 to 49.2 kg / c).
The method according to claim 1, which is within the range of m ² ). 11. The method of claim 1 wherein heating to the mat during step (d) ranges from ambient temperature to 450 ° F. (232 ° C.). 12. The method of claim 1 further comprising the step of drying the wood particles to a moisture content of 6% or less prior to step (b). 13. The method of claim 1 wherein the amount of binder mixed with the wood particles during step (b) is in the range of 2 to 15% by weight as solids, based on the dry weight of the wood particles. 14. The method of claim 13 in which the binder comprises an organic polyisocyanate having at least two active isocyanate groups per molecule. 15. The method of claim 1 wherein the liquid wax composition is further mixed with wood particles during step (b). 16. The method according to claim 1, wherein the total moisture content of the mat is in the range of 5 to 25% by weight. 17. The method according to claim 16, wherein the total moisture content of the mat is in the range of 8-12% by weight. 18. The article has a base including a main plane and a non-planar portion formed of a hollow member integrally protruding from the base; the mold has an M die and an F die, and each hollow member. 2. The method of claim 1 including a cavity for forming; and step (b) directly forming the mat having a substantially uniform thickness on the F die.