US2915821A - Hand operated metal panel cutters - Google Patents

Description

Dec. 8, 1959 Mr E. PARTIN HAND OPERATED METAL PANEL CUTTERS Filed Dq. 15, 1958 United States Patent 2,915,821 HAND OPERATED METAL PANEL CUTTERS Melvin E. Partin, Glendale, Ariz.

Application December 15, 1958, Serial No. 780,582

7 Claims. (Cl. 30-449) This invention concerns hand operated metal panel cutters.

These panel cutters are of the type adapted to enter a panel, in the door of a cabinet or the like, and open up a hole by the use of a pointed portion of the blade and thereafter cut an opening in the panel either along a straight or curved line with a minimum of effort and leave a smooth edge on both of the edges of the metal along the cut.

One of the objects of the invention is to provide a cutting instrument for sheet metal having two handles, one of which is stationary relative to a cutting foot while the other handle is adapted to move up and down pivotally, relative to the first handle, move a cutting blade through a slot in the cutting foot of the stationary handle whereby a curl or thin strip of metal is cut from the sheet metal, thereby making two sheer edges to admit the blade for further cutting action and movement through the sheet metal.

Another object is to provide a sheet metal panel cutter adapted to cut flat sheets of metal from a hole formed within the metal; said cuts being made without the necessity of cutting through the edge of the metal; said cutter being provided with a stationary cutting handle having a shoe at its lower end and a movable cutter disposed therebelow and pivoted on the stationary cutter and carrying a blade positioned between the axis of pivot and the handle shank so that the blade is drawn upward through a slot in the shoe during the cutting movement and the position of sheer is advanced toward the tip of the blade and into the sheet metal during each cutting stroke.

Still another object is to provide a sheet metal panel cutter, adapted to open up a hole in a panel without damaging the edges thereof and which will cut out and remove a narrow strip or curl of metal during the process of cutting; the parts being arranged so that the cutting action is from the rear of the blade toward the tip as it enters a slot in the cutting shoe; the point of pivot of the movable hand being arranged so that the movable handle operates as a lever of the second class and the blade advances toward the point of sheer during each cutting stroke, while the distance from the point of sheer to the handle pivot is shortened during the cutting stroke.

Other objects will appear hereinafter.

I attain the foregoing objects by means of the device, parts, and combinations of parts illustrated in the accompanying drawing, in which:

Figure l is a side elevational view of a panel cutter embodying my invention;

Figure 2 is a top view thereof;

Figure 3 is an elevational view of the cutting end thereof;

Figure 4 is a sectional view taken on line 44 of Figure 1 and drawn on an enlarged scale; and

Figure 5 is a side view of the cutting head with the movable handle at the end of a cutting stroke.

Similar numerals refer to similar parts in the several views. 1

Referring to Figure 1 the panel cutter 2 includes a stationary handle 3 having a grip 4 at its outer end, and a shoe 5 at its inner end. This shoe isformed by a continuation of the shank portion 6 of the handle which is bent angularly downward at its inner end 7 and then bent at right angles to the downwardly bent portion 7 to form the shoe 5. The bottom shoe face 8 is shaped like an elongated oval. The toe 10 is somewhat rounded as is the heel 12. A centrally positioned rectangular opening 9' or slot admits blade 25 on handle 20.

Within the curved portion C of the stationary handle 3 between the shank 6 and the bent end portion 7 there is a web 14 which is drilled to receive a pivot screw 15. This forms a pivot bearing for the movable lower handle 20. The lower handle has a shank 21 with a grip 22 at its outer end and a pivot bearing 23 at its inner end which is slotted to receive web 14 and drilled to receive screw 15. The grips 4 and 22 are adjacently positioned similar to handle grips or loops on conventional shears. The lower or movable handle 20 pivots on screw 15. Outward from the pivot screw 15 the handle shank 21 is slotted at 35 to receive the upturned shank 24 of an L-shaped cutter blade 25. The cutting portion 26 of blade 25 extends below and substantially parallel to shank 21 and has a flat upper face which is sharpened along the edges 29 where this flat face joins the side flanks 27 of the blade. An auxiliary cutting edge 28 is formed as a sharpened single edge along the curved lower end portion of the blade 25. As the blade cutting portion 26 moves upward through slot 9 the edges 29 have a shearing action relative to the sharpened edges 31 of slot 9 in shoe 5. These edges are formed along the junction of the sides 32 of slot 9 and the bottom face 8 of the shoe. There is a clearance of about two and one half thousandths of an inch between each edge 29 and the adjacent side 32 of slot 9. This is necessary to allow for the flow of the metal sheet A being cut.

As shown in Figure 1 the grip portions of the handlesv are close together and it may be considered that the movable handle is at the end of its cutting stroke. It will be noticed that only the tip portion 30 of blade 25 protrudes through the slot 9 in the shoe 5. Moving handle 20 downward moves blade 25 to the position shown by dotted outline 25a, Figure 5. This is the open position.

With the face 8 of the foot 5 placed flat on the sheet metal material A which is to be cut and after an entrance hole is made in the material, either by forcing the blade tip 30 through the material or by separately drilling a hole, the tip 30 is worked into the hole by a rocking motion and the hole opened by using the sharpened underside 28 of the blade.

After the blade is inserted the main cutting action is commenced by working handle 20 upward relative to the handle 3. The top of the blade then functions as a double edge cutter in slot 9 and removes a strip or curl K of metal from the sheet A. This curl is in the form of a narrow strip made by the cutting action of each top side edge 29 of blade 25 as it shears against the sides of the slot 9. The upward motion of handle 20 moves blade 25 from the dotted outline position 25a to the position shown in solid lines 25, in Figure 5. Likewise, the handle 20 moves from position 2001 to position 20. During this cutting motion the blade edge 26 moves accurately upwardly and forwardly. This draws the cutting edge upwardly and forwardly through slot 9 and forces curl K upwardly and forward out of the kerf formed by the out. There is also a sliding movement of the blade relative to the metal. The resulting cut is clean and sharp. It

Patented Dec. 8, 1959;

is to be noted that the movable handle operates as a lever of the second class and that as each cutting stroke progresses the leverage of the handle increases. That is the force applied to the grip 22 becomes more effective as the point of cut D advances toward the axis of pivot which is the axis of screw 15.

It is known that in many metal cutters of the snip or scissors type the cutting action requires more force to be applied to the grip ends of the handles as the point of cut nears the ends of the blades than is required when the cutting movement is started. These snips or scissors are constructed as levers of different classes than that of the handles and blade and shoe shown here. Therefore the cutter blade 25 has more cutting force as grip 22 approaches grip 4, assuming that the force applied to the grip is the same throughout the cutting stroke.

It is also to be noted that the flanks 27 of blade 25 converge smoothly towards lower edge 28. This structure permits the tool to cut in a curve line in either direction. The blade tip 30 moves easily in the kerf in sheet A and there is suifice clearance between the blade flanks and the material of sheet A (or any other similar material) to allow the blade and shoe to follow any curve desired. The standard types of curve cutters heretofore used cannot cut the curves as heretofore mentioned.

I claim:

1. A hand operated metal panel cutter composed of a stationary handle having a shoe on its downwardly curved inner cutting end extending beneath said handle, a bottom cutting face on said shoe having a centrally disposed longitudinally extending slot adapted to receive a cutting blade, a movable handle pivotally attached at its forward end to the inner side of the curved portion of the stationary handle; an L-shaped fiat blade having an upturned shank attached to said movable handle at a position rearward from its pivotal attachment to the stationary blade and a forwardly extending cutting portion ending in a point; the upper face of said cutting portion being flattened to provide cutting edges at its junction with the side flank faces of the blade.

2. A hand operated metal panel cutter composed of a stationary handle having a shank, a hand grip at the outer end of the shank and a downwardly bent portion at its inner end and a shoe extending at right angles to said bent portion of said handle; said shoe extending beneath said shank and having a smooth bottom face and having a centrally positioned longitudinally extending slot adapted to receive a cutting blade; a Web having a pivot bolt hole extending below said bent portion of said handle; a movable handle having a shank, a hand grip at its outer end and a pivot bearing at its inner end pivoted to the web on the stationary handle; a flat blade secured to the shank of said movable handle outward from said pivot bearing and extending below and substantially parallel to said handle shank; said blade having a flat face and parallel side Hanks and longitudinally extending parallel cutting edges along the sides of said flat upper face, and said pivot bearing being disposed relative to said shoe and blade so that said blade enters said slot with an arcuately upward and forward motion when said movable handle is pivotally moved upward toward said stationary handle.

3. The device as described in claim 2 wherein the slot in the shoe has a width sufficient to provide a clearance between the cutting edges of the blade and the cutting edges of the slot in the shoe to allow the metal being cut to flow slightly during cutting action and prevent choking of the cutting action.

4. The device as described in claim 2 wherein the blade is a substantially L-shaped piece of metal with the cutting blade extending at right angles to the shank, and wherein the movable handle has a vertical slot disposed outward from the pivot bearing, removably holding the shank of said blade.

5. The device as described in claim 2, wherein the cutting blade is placed between the pivot bearing and the handle grips, and has its main cutting edge extending forward through the slot in the shoe of the upper bearing, so that during the cutting movement of the blade the distance between the place of cut and the pivot bearing axis shortens, thereby increasing the mechanical advantage of the leverage when force is applied to the handle grips.

6. The device as described in claim 2, wherein the blade has a flat upper main cutting edge and side flanks smoothly tapering toward a lower cutting edge, and wherein there is a clearance between the side flanks and the side edges of the slot in the stationary handle shoe whereby the direction of cut may be varied either to the left or the right of the center of the cut to enable the user to cut circles or curves in either direction.

7. The device as described in claim 2, wherein the lower handle has a slot to receive the upwardly extending shank of a cutting blade and a screw extending through the slot in the cutting blade and the shank to removably secure the blade in the movable handle.

No references cited.

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