Base for a paper punch and method of forming same

A method of forming a base (118) for a paper punch (154) is disclosed as including the steps of (a) providing a cast iron core (102) with a wall (104) and a plate (106) with a hole (108); (b) providing two generally U-shaped cast iron plates (110); (c) positioning the plates (110) spaced apart from and on opposite sides of the core (102); and (d) insert-molding the core (102) and plates (106) with a plastics material, e.g. ABS.

This invention relates to a base for a paper punch and a method of forming such a base and, in particular, such a base for a paper punch suitable for paper crafting purposes.

BACKGROUND OF INVENTION

In the field of paper crafting, pieces of paper or cardboard of various shapes are punched out from sheets of paper or cardboard by paper punches. A conventional paper punch is shown inFIGS. 1 and 2and generally designated as10. The paper punch10has a operating handle12operatively associated with a main body14. A generally horizontal slot16is provided in the main body14, for insertion of a sheet of paper or cardboard18. The operating handle12may then be pivoted downwardly to move a punch die (seeFIG. 4) to punch or cut out a piece of shaped paper or cardboard18afrom the piece of paper or cardboard18, as shown inFIG. 3.

As shown inFIG. 4, the operating handle12is pivotable about a point20to bear down on a metal punch die22to move vertically downward to pass through a slot24between an upper jaw26and a lower jaw28of a metal base30to perform the cutting action. Upon release of the downward force, a spring32provided between the punch die22and the base30acts to return the punch die22to the upper stable position as shown inFIG. 4.

In a conventional paper punch, the die and the die holder (also called a “base”) are made of metal or metal alloy (such as copper, aluminium, silver, zinc or tin) by low pressure die cast, e.g. by injection molding. Although it has been known that the cost of the product may be reduced if at least part of the die or base is made of a plastics material, it has long, been held by people in the field that such may jeopardize proper alignment between the die and the base, in particular during the course of relative movement between the die and the base in the punching action. It is also believed that the strength and rigidity of the base may be compromised if part of it is made of other materials, e.g. a plastics material.

It is thus an object of the present invention to provide a base for a paper punch, a paper punch with such a base, and a method of forming such a base in which at least part of the base is made of a plastics material, while minimizing the aforesaid envisaged shortcomings, or at least to provide a useful alternative to the trade and public.

SUMMARY OF THE INVENTION

According to a first embodiment of the present invention, there is provided a method of forming a base for a paper punch, including the steps of (a) providing a core part with a wall member and a plate with at least one hole; (b) providing at least two generally U-shaped plate members; and (c) insert-moulding at least said core part with a plastics material.

According to a second embodiment of the present invention, there is provided a base for a paper punch, including a body part fixedly engaged with a core part with a wall member and a plate with at least one hole, and two generally U-shaped plate members spaced apart from and on opposite sides of said core part; wherein said core part and plate members are made of a material different from that with which said body part is made.

According to a third embodiment of the present invention, there is provided a paper punch including a die and a base, said base being formed by a method including the steps of (a) providing a core part with a wall member and a plate with at least one hole; (b) providing at least two generally U-shaped plate members, and (c) insert-moulding at least said core part with a plastics material.

According to a fourth embodiment of the present invention, there is provided a paper punch including a die and a base, said base including a body part fixedly engaged with a core part with a wall member and a plate with at least one hole; and two generally U-shaped plate members spaced apart from and on opposite sides of said core part; wherein said core part and plate members are made of a material different from that with which said body part is made.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

According to a first method for forming a base according to the present invention and as shown inFIG. 6, there is firstly formed a cast iron core102with a cylindrical wall104and a plate106in which a shaped through hole108is formed. The plate106is perpendicular to the wall104. The shaped108is sized and shaped to receive the cutting edge of a corresponding punch die (not shown). The core102may be formed of other metals, metal alloys, or some other suitably strong materials.

Two generally U-shaped cast iron plates110are also provided. Each U-shaped plate110has two arms112a,112bwhich are spaced apart from each other by a gap114. The U-shaped plates110may be formed of other metals, metal alloys, or some other suitably strong materials.

As shown inFIG. 7, the core102and U-shaped plates110are positioned within a mould pair116formed of an upper mould116aand a lower mould116b. The plates110are on opposite sides of and spaced apart from the core102. A plastics materials, e.g. acrylonitrile-butadiene-styrene terpolymer (ABS), may be injected into the mould in the direction of the arrow A inFIG. 7to insert-mould the core102and U-shaped plates110.

A base118formed of such a method is shown inFIGS. 8 to 10, in which the U-shaped plates110, shown in phantom lines, are fully embedded within a body120. The core102is also fixedly engaged with the body120. It should be understood that although the plates110are shown here as fully embedded within the body120of the base118, it is envisaged that the plates110may be fixedly secured to the body120, yet with one of its major surfaces exposed to the outside environment.

As shown inFIGS. 11 to 13, in order to allow the base118to function, the wall104of the core102is cut by a circular cutter122to form a slot124(seeFIGS. 14 to 16) which forms, with the gaps114of the U-shaped plates110, a common opening126allowing insertion of a piece of paper or cardboard for cutting purposes.

A paper punch incorporating the base118formed according to the method discussed above is shown inFIG. 17and generally designated as150. The paper punch150has an operating handle152which is pivotable to bear on a punch die154to cause the punch die154to pass through the common opening126formed of the slot124and the gaps114of the U-shaped plates110of the base118.

It is clear from the foregoing discussion that as part of the base118is formed of a plastics material, the cost of production is reduced, without compromising the strength and integrity of the base118. The U-shaped plates110provide support and strength to the base118, and prevent deformation of the base118, in particular during the punching action.

According to an alternative method, the core102and the U-shaped plates110are formed integrally with each other of the same material (e.g. cast iron) simultaneously. They are thus fixedly engaged with each other when formed. The core102and the U-shaped plates110are then placed within the mould pair116for carrying out the insert-moulding process to form the base118.

According to a further alternative method, only the core102is placed within the mould pair116for insert-moulding. After moulding, the two U-shaped plates110are at least partly received with a respective recess on a respective side of the base118and fixedly engaged therewith by interference fit (also called “press fit”).

It should be understood that the above only illustrates examples whereby the present invention may be carried out, and that various modifications and/or alterations may be made thereto without departing from the spirit of the invention.