Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
1999-06-02
2001-03-27
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C052S592100, C052S591100
Reexamination Certificate
active
06205639
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a method for making a building board, such as a floorboard, which board is intended to be mechanically joined to similar building boards and which board comprises a board body as well as, for the mechanical joining, a metal strip which is mechanically connected to, and projects from, the board body and which is formed with a locking element intended to engage with a complementary locking groove of an adjoining building board.
More specifically, the invention relates to an improved technique for the mechanical connection between the metal strip and the body.
BACKGROUND, FEATURES AND ADVANTAGES OF THE INVENTION
A building board, for example a floorboard, provided with a projecting metal strip formed with a locking element for mechanical joining is described in WO 94/26999. The content of that document shall be considered to be part of the present description, and provides a more detailed description of how such building boards can be designed and joined together. The background, features and advantages of the invention will be described specifically for this known type of floorboard, but it should be emphasised that the invention is useful for making building board types other than floorboards, such as wall panels and roof slabs. All references to the term “floor-board” should therefore be considered to apply to building boards in general.
WO 94/26999 thus discloses a system for mechanical joining of floorboards. A first mechanical connection provides mutual vertical locking of the joint edges and may be in the form of a tongue-and-groove joint along the joint. A second municipal connection provides mutual horizontal locking of the boards in a direction at right angles to the joint edges of the boards.
In order to illustrate the situation upon which the present invention is based, reference is now made to
FIG. 1
, which shows in section a joint between two identical mechanically joined floorboards
2
. The method according to the invention is useful for making such floorboards. The design and the function of the floor-boards
2
substantially correspond to what is known from WO 94/26999. However, there are certain differences compared to the prior art with respect to the geometrical shapes of a gripping stud and a locking element.
Each board
2
has a top side
4
and underside
6
and, for illustration purposes, can be assumed to be made of a board body S of laminated fibreboard, plastic composite, wood or the like. The thickness of the body S can, for example, be 7 mm. To enable a mechanical connection, opposite joint edges
8
of the boards
2
are formed with an integrated metal strip
10
mounted at the factory, as well as a locking groove
16
. The strip
10
is preferably made of sheet aluminium and extends horizontally from the underside
6
of the board
2
in the direction of the second floorboard and runs continuously throughout the entire length of the joint. However, the strip
10
can be divided into smaller parts, which cover the main portion of the length of the joint.
In order to achieve the required joint tolerances as well as simple laying, the strip
10
is integrally formed with the board, i.e. it is mounted at the factory and should specifically not be mounted in connection with laying. As a non-restrictive example, the strip
10
may have a width of about 30 mm and a thickness of about 0.6 mm. Metal sheet materials other than aluminium could also be used.
Along its one side edge, the strip
10
is formed with a locking element
12
, bent from the sheet material, which exhibits an active locking surface
14
having a height of e.g. 1.0 mm. In the joined state, the locking element
12
is received in a locking groove
16
, formed in the underside
6
of the second board and extending parallel to and spaced from the joint edge
8
. The locking element
12
and the locking groove
16
together form the above-mentioned second mechanical connection, locking the boards
2
to each other in the direction designated D
2
. More specifically, the locking surface
14
of the locking element
12
serves as a stop with respect to the surface
18
of the locking groove
16
closest to the joint edges
8
.
When the boards
2
are joined together according to
FIG. 1
, they can occupy a relative position in the direction D
2
where a small play &Dgr;, as small as 0.01 mm, exists between the locking surface
14
and the locking groove
16
. This play makes it possible to displace the boards
2
in the direction of the joint without the use of tools. This displaceability facilities the laying and enables joining together the short sides by snap action. Reference is made to WO 94/26999 for a more detailed description of the function and advantages of this construction.
The strip
10
is mounted in a tolerance-equalising groove in the underside
6
of the board
2
. In this embodiment, the width of the equalising groove is approximately equal to half the width of the strip
10
, i.e. about 15 mm. The functioning of and different ways of forming the equalising groove are described in detail in WO 94/26999 and, consequently, need not be repeated here.
The strip
10
is mechanically fitted to the body S in the following manner. A groove
20
is provided in the underside
6
of the body S at a distance from a recess
22
adjacent to the joint edge
8
. The groove
20
may be formed either as a continuous groove extending throughout the entire length of the body S, or as a number of separate grooves. Together with the recess
22
, this groove
20
defines a dove-tail gripping stud
24
of the body S. In its fastened state in
FIG. 1
, the strip
10
exhibits a number of punched and bent tongues
26
as well as one or more lips
28
, which are bent round opposite sides of the gripping stud
24
. The term “gripping element” will be used in the following as a general term for tongues, lips and corresponding components of the strip which are formed from the sheet material and bent round the gripping stud
24
of the body S.
SUMMARY OF THE INVENTION
A main object of the invention is to provide a technique for improving building boards of the type mentioned above.
A particular object of the invention is to provide a technique for improving the mechanical fastening of the strip to the body.
It is also an object of the invention to provide a technique for improving a manufacturing method for building boards of the type mentioned above.
For achieving these and other objects, according to the invention a method is provided for making a building board having the features recited in the appended claims.
Thus, the invention provides a method for making a building board, which exhibits a board body formed with a gripping stud, and a metal strip extending from the body, from which are formed gripping elements which are bent round the gripping stud for mechanical fastening of the strip to the body, as well as a locking element for enabling mechanical joining of the board to similar boards. The method is characterized by preforming the gripping elements of the strip prior to bending them round the gripping stud, and subsequently bending the preformed gripping elements round the gripping stud, the preforming being such that, as a result of the bending, the preformed gripping elements strike against the gripping stud and thereby undergo a deformation in the opposite direction to the preforming in a final stage of the bending.
The preforming which occurs during said final stage of the bending preferably results in a biasing of the gripping elements of the strip against the gripping stud.
The preforming as well as the bending of the gripping elements are preferably carried out by means of punching means operating essentially at right angles to a principal plane of the strip/building board, and, in a particularly preferred embodiment, such punching means are arranged in one and the same punching tool so that they are stationary in relation of each other during the preforming and the bending.
For achieving good fastening, and for elimina
Burns Doane , Swecker, Mathis LLP
Cozart Jermie E.
Hughes S. Thomas
Valinge Aluminum AB
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