CA1178426A

CA1178426A - Tubecutter

Info

Publication number: CA1178426A
Application number: CA000396217A
Authority: CA
Inventors: Daniel Forget; Georgina Forget
Original assignee: Individual
Current assignee: SPECIALTY TOOLS OF CANADA Inc
Priority date: 1982-02-12
Filing date: 1982-02-12
Publication date: 1984-11-27

Abstract

TUBECUTTER

ABSTRACT
This invention is directed to a handy tool for readily cutting tubes, hoses, wire and other resilient elongated or cylindrical materials. The tool comprises a pair of scissorlike arms, which are pivotally secured to one another, a flat pointed shearing blade secured to the upper jaw of one of the arms and a blade receiving depression formed in the lower jaw of the other arms.
The intersection of the point of the cutting blade is offset from the centre line of the blade receiving depression formed in the lower jaw.

Description

T~BECUTTER

~IELD OF THE INVENTION
This invention is directed to a han(1y tool for readily cutting tubes, hoses, wire and other resilient or semi-resilient cylindrical or elongated materials.
BACKGRO~ND OF THE INVENTION
There is a strong need in the domestic and industrial worlds for a handy, reliable, easily portable tool which will readily and evenly cut rubber and plastic tubes, hoses, wire and other generally cylindri-cal or elongated resilient or semi-resilient materials such as insulation for electrical wiring and plastic water pipes. Any tools which are commonly available on the marketplace ~lave the disadvantage that they tend to compress or crush the tube hose, or the like, as it is being cut. Consequently, the cut is made while the tube is in a distorted condition and hence when the tube returns to its origindl position after the cut has been made, the cut edges are uneven and sometil~es jagged. A
smooth clean cut is thus not achieved by these conven-tional tools. Furthermore, the pressure re~uired to force the cutting edge of the tool through t}le resilient material is relatively high.
The applicant is aware of the folLowing references which disclose cutting devices of one type or another.

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U.S. Patent No. Inventor Issue Date

2,248,642 C.R. Phillips July ~, 1941 2,516,959 W.I. Coull Aug. 1, 1950 2,539,124 E.W. Findlay Jan. 23, 1951 2,975,518 P.N. Nelson March 21, 1961

3,807,046 Igyarto et al. Apr. 30, 1974 3,861,035 Ramey et al. Jan. 21, 1975 Igyarto shows a cutter for use in cutting relatively soft tubing. However, Igyarto does not disclose a cutting device which operates in a scissor-like fashion. His device operates in a pivotal manner much like a paper stapler. This is awkward and generally means that more hand pressure is required to cut the article since no mechanical advantage is provided. Furthermore, the tube to be cut is not cradled so as to reduce the tendency of the tube to compress as it is being cut, thereby resulting usually in an uneven cut of the tube.
SUMMARY OF THE INVENT~ON
I have invented a scissor-like tube cutter which cuts tubes, hoses, wire, or similar resilient or semi-resilient articles, with a minimum amount of pressure and provides a clean straight smooth cut edge.
The jaws of the cutter are formed to provide a cradle for the tube to be cut, thereby holding and evenly distributing the pressure applied to the tube and tending to minimize tube distortion and movement.
Furthermore, the point and two cutting edges of the flat blade are offset of centre and are of uneven angle. In this way, the point or intersection of the two cutting 117~

edges does not meet squarely with the centre line of the tube, which is resting in the cradle. Thus th~ shearing action imparted by the point and cutting edcJes of tJle blade on the tube is initiated at a point of~set oE the S centre line of the tuhe. This action tends to distrib-ute the shearing forces around the circumference of the tube, rather than directing them throuc~h the centre-line of the tube. This diverting action thereby tends to minimize the compression effect on the tube anc~ minimize the shearing forces that are required to cut the tube.
The result is a straic3ht, even, clean cut of the tube with minimum manual pressure required.
The invention is directed to a tube cutter comprising a pair of scissor-like arms, whic;l are pivotally secured to one another to provide a pair of jaws ancl a pair of handles, a flat pointed shearin~3 blade secured to the under side of the upper jaw of one of the arms; a blade and tube receiving depression ormed in the upper sicle of the lower jaw o~ the pair of arms; the intersection of the point of the cutting blade being offset from the centre line of the depression formed in the lower jaw.
In the cutting device, the interior angle of the point of the flat cutting blade may be in the range of about 70 to 100, in the restricted range of about 80 to 90, or preferably about ~5. The clepression formed in the lower jaw of the device may be V-shaped in confic~uration to ideally receive and cradle tubes or the like in a direction lateral to the alignment of the upper anc3 lower jaws.

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The cutting surface of the cutting blade may be machined to have in section a V-shaped first cutting surface and a bevelled upper ~econd surfac~, th~ second surface being of an acute angle less than the acute angle of the first cutting surface. The cutting blade throughout its travel distance does not contact the lower jaw of the cutting device.
In the cutting device according to the invention, the cutting blade may have forwardly and rearwardly cutting edges, the forwardly cutting edge being at an angle within the range of about 20 to 60 with the horizontal and the rearwardly cutting angle being at an angle within the range of about 35 to 75 with the hori~ontal. On a more restricted basis, the frontwardly cutting edge may be within the range of about 30 to 50 with the horizontal while the rear-wardly cutting edge may be at an angle in the range of about 45 to 65 with the horizontal. Pre~erably the cutting angle of the forward cutting edge ~ay be at an angle of about 40 from horizontal, wi~h the cutting angle of the rearwardly cutting edge being at an angle of about 55 with the horizontal.
In the cutting device, the flat cutting blade may be of generally pentagonal or rectangular configuration, two adjacent edges thereof being machined to form a sharp cutting edge.
DRAWINGS
In the drawings, which depict the invention:
FIGURE 1 represents a side elevation view of the tube cutter with a tube resting in the craclle of the lower jaw of the cutter;
FIGURE 2 represents a top elevation view of the tube cutter;
FIGURE 3 represents a section view taken along section line A-A of Figure l;
FIGURE 4 represents a side elevation view of one desiqn of cutting blade;
FIGURE 5 represents a side view of a second design of cutting blade; and FIGURE 6 represents an end elevation view of the cutting blade showing the double angled cutting edge.
DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION
Referring to FIGURE 1, which depicts a side elevation view of the tube cutter lj~the tube cutter 1 operates in a scissor-like manner about a pivot point, the upper jaw 2 moving upwardly or downwardly about the pivot point relative to lower jaw 3 in the ~lanner of ordinary scissors.
The upper jaw 2 holds and has secured thereto on the underside thereof a pointed cutting blade 4. The blade 4 is held in place on the upper cuttiny jaw 2 by means of a first holding pin 5 and a second holding pin 6. The underside of the upper jaw 2 has formed therein an upper hollow (preferably an inverted V-shape) which serves to receive the tube 9 without interference with jaw 2, as the upper jaw 2 and blade 4 are lowered in the direction of the lower jaw 3.
The lower jaw 3 has formed on the upper surface thereof a lower hollow or tube cradle 8, which -~5 -is preferably V-shaped and receives and cradles the circumference of most common tubes or similar resilient or semi-resilient articles on the market. The function of the tube cradle 8 is to accommodate and hold securely various diameters of tubes, or the like, and to evenly distribute the cutting forces throughout the contacting surface of the tube 9 as it is being sheared by descending cutting blàde 4. The V-shaped cradle 8 prevents the tube 9 from squirming as it is Cllt.
The cutting point 10, it will be noted by means of FIGURE 1 and the directional travel line indicated on that drawing, meets the top of the tube 9 at a point which is offset from the centre line of the tube 9. As shown in FIGUR~ 1, the off-set is in the direction of the pivot point of the cutting tool 1. An off-set to the other side of the centre-line of the tube 9 is also feasible. The off-set is ilnportant because the force applied by the point 10 on the tube 9, as point 10 moves downwardly, tends to be distributed somewhat circumferentially around the tube 9, and thereby minimizes the forces which would tend to distort the shape of tube 9 as it is cut. If the point 10 met the tube 9 on its centre-line, the cutting force would be directed partly to distorting or compressing the 2S tube 9. Such tube distortion action causes the tube 9 to be cut while in a distorted condition which results in an uneven cut when the tube 9 springs back to its unstressed condition after being cut. It also re~uires the application of more than minimal cuttiny pressure.
The point 10 ensures that tube cutting action is commenced at a point rather than over an are~.
Cutting action is therefore initiated with a Inirlir~um of pressure and tu~e distortion. This would no~ be th~
case if the cutting blade 4 had a curved or str~ight cutting edge. Furtl~ermore, it will be noted th~t the Eirst cutti~ng ed3e 11 of the blade 4 is at a more horizontal related angle than the cutting angle of the second cutting edge 12. These different cutting angles 11 and 12 spread the direction of the cutting forces and maximlze the cutting ability of the respect-ive cutting edges. The different angles also minimize the tube distortion effects of the blade ~ as it is applied downwardly in cutting tube 9. These different cutting blade edge angles therefore contribl~te to the tube 9 being sheared cleanly and evenly with I~inimum pressure.
As seen in FIGURE 4, the cutting blade 4 at its top edge has formed therein a pair of holcliny pin slots 13, which match with the pair of first and second holding pins 5 and 6 in the upper jaw 2.
Numerous trial tests have been conducted and it has been determined that the optimum angle of the point 10 is an interior angle in the neighbourhood of 8S.
Interiorpoint angles in the range of about 80to 90 have been found to perform reasonably ~rell w~ile interiorpoint angles in the range of about 70 to 100 perform ade~uately. The first cutting edge 11 is o~ti,nally of about 40 with the horizontal. The optimum angle of the second cutting edge 12 is optimally of abo~t 55 with the horizontal. Angles within the range of about 30 to 50 with the horizontal for the first cutting edge 11, and angles within the range of about ~5 to 6S with the horizontal for the second cutting edge 12 have ~een found to perform satisactorily. It is understood that the first and second edges may be reversed - the key beiny that the angle of the one cutting edge is different from the angle of the other cuttinc~ edge to provide optimum cutting capability.
FIGURE 3 illustrates a section view taken along section line A-A of FIGURE 1. It will be noted that the cutting blade 4 does not contact the lower jaw 3 at any point. The tube shearing action is achieved solely by the cutting blade 4 proceeding through the tube 9, and does not depend upon shearing contact between the blade 4 and the lower jaw 3, as is the function with a normal scissor cutting action.
Referring to FIGURE 6, which illustrates an end or section view of the cutting blade 4, it can be seen that the cutting edge of the blade 4 is machined to have two complementary facing surfaces, one above the other. The initial cutting edge and surface 14 is machined so that it has an acute cutting angle of about 25. For various applications, however, it may be found that cutting angles of the initial cutting surface 14 falling within the range of about 2Q to 30 may be satisfactory. Machined above the initial cutting surface 14, in complementary facing surfaces, are a pair of bevelled sur~aces 15. These second surfaces 15 are machined to have an effective acute angle of about 20.
The two second surfaces 15, being machined at an angle :;~ 1 '7~

which is more acute than the angle of the two initial cutting surfaces 14, enables the tube 9 as it is being cut to clear contact with the cuttiny blade 4 at an early point and thereby reduces friction and the cutting pressure that must be applied to the cutter 1 in order to cut the tube 9. This existence of the second surfaces 15 ensures that the blade 4 does not contact the tube 9 for an extended length of travel of the blade 4 through the tube 9 as the tube 9 is sheared. If an acute angle of more than or less than 25 Eor the pair of surfaces of the initial cutting edge 14 is selected, then it follows that the effective acute angl-e of the pair of second surfaces 15 must be less than that to achieve the friction reducing benefit.
FIGURE 5 illustrates an alternative construction of cutting blade 16. The first cutting angle 18 and the second cutting angle 19 are basically the same as the corresponding cutting angles for the blade 4. However, only one holding pin slot 17 is formed in the top portion of the cutting blade 16. The cutting blade 16 is basically rectangular in shape, which means that a series of cutting hlades 16 can be formed from an elongated rectangular piece of blade stock, as illustrated in FIGURE 5 by the dotted lines which extend upwardly to the right from cuttillg blade 16. A disadvantage with the pentagonal shape of cutting blade 4, as depicted in FIGURES 1 and 4, is that there is a certain amount of wastage of valuable carbon steel as the pentagonal shape is punched or cut from blade stock. To accommodate the rectangular shape of cutting blade 16, as depicted in FIGURE 5, the upper jaw 2 of the tube cutter 1 is modiEied to have only one holding pin, and to have a right angled sèat oE
accommodating construction formed in the upper jaw 2 50 that the blade 16 is prevented from SwingincJ or pivoting about holding pin slot 17, as force is applied on the blade 16 in order to shear a tube 9.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.

Claims

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. A cutting device comprising:
(a) a pair of scissor-like arms, which by being pivotally secured to one another, provide a pair of jaws and a pair of handles which can be opened or closed relative to one another;
(b) a flat pointed cutting blade secured to .
the underside of the upper jaw of one of the arms, the plane of the blade being in alignment with the plane of movement of the jaws and handles;
(c) an object receiving depression formed in the upper side of the lower jaw; and (d) the point of the flat blade being offset either rearwardly or forwardly from the centre line of the depression formed in the lower jaw when the jaws are closed together.

2. A cutting device as claimed in Claim 1 wherein the interior angle of the point of the cutting blade is in the range of about 70° to 100°.

3. A cutting device as claimed in Claim 1 wherein the acute angle of the cutting blade is in the range of about 80° to 90°.

4. A cutting device as claimed in Claim 1 wherein the acute angle of the point of the cutting blade is about 85°.

5. A cutting device as claimed in Claim 1 wherein the depression formed in the upper side of the lower jaw of the device is V-shaped in configuration.

6. A cutting device as claimed in Claim 1, 2 or 3 wherein the cutting surface of the cutting blade is machined to have in section a V-shaped first cutting surface and a bevelled second surface above the cutting surface, the second surface being of an acute angle less than the acute angle of the first cutting surface.

7. A cutting device as claimed in Claim 1, 2 or 3 wherein the cutting blade does not contact the lower jaw of the cutting device at any time.

8. A cutting device as claimed in Claim 1, 2 or 3 wherein the cutting blade has linear forwardly and rearwardly extending cutting edges falling in the plane of the cutting device, the forwardly cutting edge being at an angle in the range of about 20° to 60° with the horizontal, the rearwardly cutting edge being at an angle within the range of about 35° to 75° with the horizontal.

9. A cutting device as claimed in Claim 1 wherein the frontwardly cutting edge is at an angle within the range of about 30° to 50° with the horizontal while the rearwardly cutting edge is at an angle within the range of about of 45° to 65° with the horizontal.

10. A cutting device as claimed in Claim 9 wherein the cutting angle of the forwardly cutting edge is about 40° with the horizontal whereas the cutting angle of the rearwardly cutting edge is about 55° with the horizontal.

11. A cutting device as claimed in Claim 1, 2 or 3 wherein the flat cutting blade is of generally pentagonal configuration, two adjacent edges thereof being machined to form a sharp cutting edge.

12. A cutting device as claimed in Claim 1, 2 or 3 wherein the flat cutting blade is of generally rectangular configuration, two adjacent edges thereof being machined to form a sharp cutting edge.