EP0827815A1 - Pliers for cutting transversely plastic tubes - Google Patents

Abstract

The cutting pliers comprises two branches (3,4) pivoted to each other about a transverse spindle (5). One branch has a cutting blade (40) at its end and the other branch end has a hollow seat (30) for receiving the tube. The blade has two cutting edges (41,42) forming an obtuse angle of between 120<o> and 150<o>. This is such that the angle ( alpha ) between the cutting edge (41) furthest from the spindle and a straight line (F) passing through a point (43) in the blade and the spindle, is greater than the angle ( beta ) formed by the other cutting edge and the line. The point describes during pivoting a circular arc (A) which cuts the line segment (D) joining the spindle and the tube centre (C) of larger diameter resting in the seat. The start of the cut is made by the point and the end of the cut is made only by the cutting edge (41) furthest from the pivoting spindle.

Description

The present invention relates to a device of pipe cutter pliers to cut a tube transversely plastic material.

We already know tube cutter clamp devices, they both comprise articulated branches, one to the other around a transverse axis, one of which includes its end a cutting blade, while the end of the other comprises a seat intended to receive the tube with cut.

In general, a pipe cutter has a blade with a straight edge, which presents the disadvantage of requiring significant effort at the start cutting, indeed the cutting edge attacks the tube tangentially and the tube tends to slightly flatten, so that the contact area between the sharp and the tube is a line, making the primer of difficult cutting, with risk of crushing the tube and therefore deformation of it.

This disadvantage manifests itself more especially when the tubes are of a large diameter, and more precisely when the diameter / thickness ratio of the tube is large, since the tube is then less rigidity.

To partially overcome this drawback, some have proposed tube cutters allowing to make a so-called "pulling" or "pulling" cut, that is to say that instead of placing the pivot axis near the line coinciding with the cutting edge, said axis is distant, so that with the classic cut is associated a translational movement of the cutting edge on the object to be cut.

Others have proposed clamp devices pipe cutter comprising, like pipe cutters of the type guillotine, a two-edged blade at an angle obtuse projecting and having a point which makes it possible to initiate cut with little effort, and avoid crushing the tube, on the other hand, at the end of cutting the two cutting edges attack the inner wall simultaneously and tangentially of the tube, which requires significant effort.

However, it would be possible to remedy this disadvantage of using a blade with two cutting edges would form an acute angle, but this would require a large blade stroke, therefore a large distance branches of the tool, which would not facilitate its use.

We also know, from document CA-A-1 178 426, a tube cutter clamp device which comprises a blade with two cutting edges making an angle between them 70 ° and 100 °, preferably 85 °, the closest cutting edge of the pivot axis at an angle to the horizontal between 20 ° and 60 °, preferably 55 °, while the other cutting edge makes an angle with the horizontal included between 20 ° and 60 °, preferably 40 °.

If this device allows the realization of a more efficient cutting than other existing devices, it nevertheless has several drawbacks, on the one hand the angle made by the cutting edges requires a large branch opening, which requires significant force at the start of the cut and limits the cutting capacity, and on the other hand, at the end of the cut, despite the angular offset cutting edges with respect to the horizontal, there remains a phase where said cutting edges attack the wall of the tube by the interior simultaneously and tangentially, with consequently the need for a significant effort.

The object of the present invention is to remedy these various drawbacks by proposing a clamp device pipe cutter whose use is easier than that of existing devices, since they do not require any effort important whether at the beginning or at the end of the cut.

The tube cutter clamp object of the present invention comprises two branches articulated in pivot to each other around a transverse axis, of which one has a cutting blade at its end, while that the end of the other has a hollow seat intended to receive the tube to be cut, and it is characterized essentially in that said blade has two cutting edges forming a projecting obtuse angle between them between 120 ° and 150 °, and so that the angle formed by the cutting edge farthest from said axis and a straight line passing by the tip of said blade and said axis is larger that that formed by the other cutting edge and said straight line; and in that said tip describes, during its pivoting, a arc of circle which cuts the line segment which joins said pivot axis and the center of the larger tube diameter likely to rest in said seat, so that the initiation of the cut is made by said point and that the end of cut is carried out only by the cutting edge farthest from said pivot axis.

According to an additional characteristic of the device according to the invention the edges of the blade make an angle of 135 °.

According to another additional characteristic of the device according to the invention, the circular arc that describes the point of the blade cuts the line segment joining the axis pivot in the center of the larger diameter tube likely to rest in the seat, at a point in the middle region of the radius of said tube.

According to another additional characteristic of the device according to the invention the angle formed by the cutting edge farthest from the pivot axis and the straight line passing by the point of the blade and said axis is double that of formed by the other cutting edge and said straight line.

The tube cutter device according to the invention is designed to optimally cut a tube with a diameter which corresponds to that of the headquarters. However, it allows cut tubes of smaller diameter, even those with diameter is too small to allow cutting to begin blade tip means, in fact, in this case the ratio tube diameter / thickness is small, and the cutting edge further from the pivot axis then suffices for the achieving a perfect cut without significant effort, as much as said cutting is carried out "by pulling".

In addition, to allow the setting of a tube of very small diameter, so that it does not escape from the seat when of the section, said seat has on its edge the most away from the pivot axis a notch where can come wedge said tube.

Furthermore, the cutting effect "pulling" at tendency to bring the tube towards the bottom of the seat.

The advantages and features of the present invention will emerge more clearly from the description which follows and which relates to the appended drawing, which represents a non-limiting embodiment thereof.

• les figures 1a et 1b représentent des vues schématiques partielles d'un dispositif de pince coupe-tube existant, lors de deux étapes d'une coupe.
• les figures 2a et 2b représentent des vues schématiques partielles d'un autre dispositif de pince coupe-tube existant, lors de deux étapes d'une coupe.
• la figure 3 représente une vue en plan d'un dispositif de pince coupe-tube selon l'invention.
• les figures 4a, 4b, 4c et 4d représente des vues schématiques du même dispositif, lors de différentes étapes de fonctionnement.

In the attached drawing:

• Figures 1a and 1b show partial schematic views of an existing tube cutter clamp device, during two stages of a cut.
• Figures 2a and 2b show partial schematic views of another existing tube cutter clamp device, during two stages of a cut.
• FIG. 3 represents a plan view of a tube cutter clamp device according to the invention.
• Figures 4a, 4b, 4c and 4d show schematic views of the same device, during different stages of operation.

If we refer to Figures 1a and 1b we can see an existing pipe cutter clamp, including a seat 1 intended to receive a tube 2 to be cut, and a blade 10 which has a straight edge 11.

On the figure we can see that at the beginning of cutting, cutting edge 11 attacks tube 2 tangentially which requires significant effort, especially as the tube 2 tends to crash.

In Figure 1b we can see that at the end of the cut there is no risk of crushing since the part of the tube 2 remaining to be cut is in contact with seat 1, by against the cutting line remains important.

If we now refer to Figures 2a and 2b we can see another tube cutter clamp device existing, which includes a blade 12 comprising two cutting edges 13 and 14 forming an obtuse angle between them protruding, which allows to attack the tube 2 by a point 15, as can be seen in FIG. 2a, thus avoiding the risk of tube 2 being crushed, and limiting the effort to provide.

However, as shown in the Figure 2b, the end of cut requires a significant effort from causes the cutting edges 13 and 14 to attack tangentially the internal wall of the tube 2 simultaneously along two lines.

If we now refer to Figure 3 we can see a tube cutter device according to the invention, it has two branches 3 and 4 pivotally mounted on a axis 5, the branch 3 has at one end a seat 30 in shape of an arc of a circle, while branch 4 comprises its end opposite the seat 30, a cutting blade 40.

It should be noted that seat 30 can also be V-shaped

The blade 40 has two cutting edges 41 and 42 making an angle of 135 ° between them, creating a point 43, which describes, during the pivoting, an arc of a circle A intersecting at a point B the line segment D joining the axis pivot 5 and the center C of circle E which corresponds to the larger diameter tube likely to rest in the seat 30.

The length of the segment CB can be understood between the ratios R / 5 and R / 1.25, where R is the radius of the circle E, the optimum value being R / 2.25.

In addition, the angle formed by the cutting edge 41 and a straight line F passing through the axis 5 and the point 43, is more large than the angle ß formed by the cutting edge 42 and the right F. In the embodiment shown, the angles a and ß are 30 ° and 15 ° respectively.

If we now refer to Figures 4a, 4b, 4c and 4d, we can see different stages of cutting a tube 2.

In FIG. 4a, the blade 40 attacks the tube 2 by its point 43, the initiation of the cut can thus be carried out effortlessly and without deformation of the tube 2.

In FIGS. 4b and 4c, the cutting edges 41 and 42 cut the wall 20 of the tube 2 in the thickness direction which corresponds to the minimum effort required.

In FIG. 4d, the cutting edge 42 has passed through the tube 2 and the cutting edge 41 completes the cutting of the tube 2 tangentially without risk of deformation and without effort like a classic single-edged blade, benefiting from more of the "pulling" effect, due to the value of the angle at.

We can also see in these figures that the seat 30 has a notch 31 allowing the setting a small diameter tube, the cut of which will be made only by cutting edge 41.

Claims (7)

Pipe cutter clamp device for cutting transversely a plastic tube, comprising two branches (3, 4) pivotally articulated one to the other around a transverse axis (5), one of which is provided at its end with a cutting blade (40), while the end of the other has a hollow seat (30) intended to receive the tube (2) to be cut, characterized in that said blade (40) has two cutting edges (41, 42) forming between them a projecting obtuse angle of between 120 ° and 150 °, and so that the angle (α) formed by the cutting edge (41) furthest from said axis (5) and a straight line (F) passing through the tip (43) of said blade (40) and said axis (5) is greater than the angle (ß) formed by the other cutting edge (42) and said straight line (F); and in that said point (43) describes, during pivoting, an arc of a circle (A) which cuts the line segment (D) which joins said axis (5) and the center (C) of the larger diameter tube likely to rest in said seat (30), so that the primer of the cut is made by said point (43) and that the end cutting is carried out only by the cutting edge (41) the further from said pivot axis (5). Device according to claim 1 characterized in that the cutting edges (41, 42) of the blade (40) make an angle of 135 °. Device according to claim 1 or the claim 2 characterized in that the arc of a circle (A) as described by the point (43) of the blade (40) cuts the segment right (D) joining the pivot axis (5) to the center (C) larger diameter tube likely to rest in the seat (30), at a point (B) located in the middle region the radius of said tube. Device according to claim 3 characterized in that the middle region is bounded by the values R / 5 and R / 1.25, R being the radius of the tube plus large diameter capable of resting in the seat (30). Device according to claim 4 characterized in that the arc of a circle (A) that describes the tip (43) of the blade (40) intersects the line segment (D) joining the pivot pin (5) to the center (C) of the larger diameter likely to rest in the seat (30), at a point (B) located at a distance of R / 2.25 from said center (C). Device according to any one of previous claims characterized in that the angle (a) formed by the cutting edge (41) furthest from the axis of pivot (5) and the right (F) passing through the point (43) of the blade (40) and said axis (5) is double the angle (ß) formed by the other cutting edge (42) and said straight line (F). Device according to any one of previous claims characterized in that the seat (1) has in its edge furthest from the axis of pivoting (5), a notch (31) allowing the setting of a small diameter tube.

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