GB2271953A

GB2271953A - Cutting elongate objects.

Info

Publication number: GB2271953A
Application number: GB9222788A
Authority: GB
Inventors: Steven Thomas Bolton
Original assignee: Hydra Tight Ltd
Current assignee: Hydra Tight Ltd
Priority date: 1992-10-30
Filing date: 1992-10-30
Publication date: 1994-05-04
Anticipated expiration: 2012-10-30
Also published as: GB9222788D0; GB2271953B

Abstract

A hydraulically operated cutter 15 for cutting a stud 10 close to a surface 11 from which it protrudes comprises a body 16 having an aperture 20 for locating it around the stud, a flat working face 17 for resting against a surface 11 and a cutter passage 22 inclined to the working face with an axis 25 intersecting the plane of the working face at the distal side of the aperture. A tapered cutter blade 30 has a cutting region 32 extending parallel to the working face and defining, with taper face 45, the lowest part of the blade so that as the blade is driven along axis 25 and through the stud it is able to effect cutting down to the level of surface 11. <IMAGE>

Description

Cutting elonaate obiects This invention relates to cutting elongate metallic objects, particularly, but not exclusively, studs, bolts, and the like and in particular relates to cutting such objects as protrude from a surface substantially at the level of such surface.

The invention takes the form of a cutter for such an elongate metallic object. Cutters for elongate metallic objects are known comprising a body, having a working face defining a datum plane, an object receiving aperture opening towards the working face and a cutter blade passage opening adjacent to the end of the aperture at one side of the aperture and having a longitudinal axis extending in a direction towards the side of the aperture opposite to said one side, a cutter blade supported in, and movable along, the passage and terminating in a cutting region displaceable, by movement of the cutter blade, across the aperture and drive means operable to move the cutter blade along the passage in the direction of said longitudinal axis.Such a cutter form is hereinafter referred to as being "of the type hereinbefore defined" and the present invention is associated with such a cutter form including a cutter blade driven, in operation, into a body contained in the aperture as distinct from a shearing between a pair of blade edges.

A requirement exists to cut through a steel stud or bolt which protrudes from a surface, such as a machine face or a rock face, such that a minimal amount of the stud remains protruding, such stud being typically of the order of 30mm in diameter. It is commonly accepted that an object of such material and dimensions requires the cutter blade to be driven by a hydraulic piston and cylinder arrangement acting against the end of the cutter blade along the longitudinal axis.However, the inevitable dimensions of such a piston and cylinder arrangement to provide the necessary cutting force means that the cutter blade or at least a tapered cutting edge thereof, is central with respect to the axis of the piston and cylinder and displaced from the periphery of the cutter tool and precluded from cutting the stud close to the surface from which it protrudes.

Notwithstanding the use of motive power other than hydraulic pressure to force the cutter blade of such a device, it is an object of the present invention to provide a cutter generally of the type hereinbefore defined that is capable of cutting an elongate metallic object closer to a surface from which it protrudes than hitherto.

According to the present invention cutter, for an elongate metallic object, of the type hereinbefore defined has the longitudinal axis of the cutter blade passage extending in a direction that is inclined with respect to the datum plane and intersects the datum plane towards the side of said aperture opposite to said one side, and has the cutting region of the blade extending parallel to the datum plane and substantially through said longitudinal axis direction and comprising for its whole length the closest part of the blade to the datum plane.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which Figure 1 is a sectional elevation through a stud cutter in accordance with the present invention shown operatively disposed with respect to a stud protruding from a surface, and Figure 2 is a plan view of a portion of the arrangement of Figure 1 showing the shapes and relative disposition of the stud, a stud containing aperture and a cutting blade.

Referring to Figure 1, a stud or bolt shank 10 protrudes from a surface 11 of a body, such as a rock face or machine to which it is firmly anchored and from which the protruding part is to be cut close to the surface 11.

A cutter device 15 in accordance with the present invention is shown in operational disposition with respect to the stud 10 and surface 11. The cutter device comprises a body 16 of steel having a working face 17 that defines a datum plane 18. The working face is conveniently coincident with the datum plane and, in the illustrated operational disposition, the datum plane is coincident with the surface 11.

The body 16 contains an object-receiving aperture 20 opening towards the working face at 21, which, as illustrated, is at the datum plane 18. The aperture has a longitudinal axis 20' extending substantially perpendicularly to the datum plane and conveniently takes a cylindrical form of circular cross-section extending completely through the body as a through aperture.

The body also contains a cutter blade passage 22 opening at 23 adjacent the end of the aperture at one side 24 of the aperture and having a longitudinal axis 25, which axis extends as a continuation of the passage across the aperture 20 towards the side 26 of the aperture opposite to said one side 24.

The cutter passage 22 contains a cutter blade shown generally at 30 comprising a body portion 31 which is movable along the passage and terminating in a cutting region 32 in the aperture 20. The passage 22 is conveniently circular in cross-section, that is, comprises a cylindrical drilling through body 16, and the cutter blade body portion 31 is correspondingly of circular cross-section. Drive means 35 comprises a cylinder 36 secured to the end of the body 16 and a piston 37 contained in the cylinder that define therebetween a fluid chamber 38 for receipt of hydraulic liquid at elevated pressure by way of coupling port 39.

The longitudinal axis of the cylinder is coincident with the longitudinal of the cylinder axis 25 of the passage and the piston 37 includes a piston rod 40 that extends along said longitudinal axis and is secured to the end of the cutter blade body remote from the cutting region.

A spring 42 surround the piston rod biases the piston away from the body 16 and serves to retract the cutter blade into the passage 22 so that only the cutting region extends into the aperture 20, where it may readily be inspected for damage and effect a limitation of the maximum diameter of stud which can be accommodated by the aperture. The drive means operates, upon receipt of hydraulic liquid, to overcome the spring bias and move the cutter blade along the passage and displace the cutting region 32 across the aperture in the direction of the longitudinal axis.

The passage 22 is inclined with respect to the datum plane at an angle, shown as ss such that the extension of its longitudinal axis intersects the datum plane 18 in line with the aperture 20 towards the side 26 of the aperture opposite to the side 24 and the rest position of the cutter blade. Although there is scope for variation in the precise point of intersection, discussed hereinafter, it is convenient, with the aperture opening at the working face/datum plane, for the intersection to occur in line with the side 26 of the aperture.

The inclination angle ss is in the range 120 to 200 but preferably is about 150.

Referring also to Figure 2 this shows a plan view of the portion of the arrangement of figure 1 in the vicinity of the aperture 20 of the device body 16, and like reference numerals are employed.

The cutting region 32 is defined by an end portion 42 of the cutter blade body tapering in thickness towards the cutting region at sides proximate to, and distal from, the datum plane as a wedge with faces 45, 46 respectively to form a linear cutting region extending parallel to the datum plane 18 and through the longitudinal axis 25 and comprising along its whole length the closest part of the blade to the datum plane. The tapering wedge faces 45, 46 are substantially equally inclined with respect to the longitudinal axis 25, at angles i ss, so that the taper 45 face proximate the datum plane extends parallel to the datum plane. The taper face 46 at the side of the longitudinal axis distal from the datum plane is shorter than the face 45 such that the significantly tapered portion is relatively short in the axial direction and more resistant to damage, its minimum length being determined by the maximum distance the blade is required to penetrate a stud to be cut.

The edge of the cutting region itself is preferably relatively blunt and radiussed as described in co-pending patent application GB9113991 (HYD 2240).

In plan view the cutting region, in a plane parallel to the datum plane, is shaped to have a substantially straight centre portion 47 with radiussed end portions 48, conveniently corresponding in curvature to the object receiving aperture 20.

The overall width of the cutting region corresponds to the width, in this case, diameter, of the cutter blade body and is smaller than the diameter of aperture 20 to permit the cutting region to be displaced across at least a major portion of the aperture without fouling the wall thereof.

As will be seen from Figure 2, a shorter straight centre portion 47 of the cutting region will permit displacement further across the aperture.

In operation, and disposed as shown in relation to a stud 10 to be cut, the working face 17 of the body 16 is supported on surface 11 with the stud extending through aperture 20, the drive means 35, by virtue of return spring 42, retracting the cutter blade to permit passage of the body over the stud. The drive means 35 is energised by pressure of hydraulic fluid supplied thereto such that the cutting edge of the cutter blade is displaced into contact with the stud and reaction to the driving force causes the body 16 at the side 26 of the aperture to bear against the stud. Thereafter the cutting region is forced to penetrate the stud and effect cutting thereof.It will be appreciated that as the cutter blade is urged along the direction of the longitudinal axis 25 the cutting edge, being the lowest part of the blade moves towards the point - of intersection with the datum plane, that is, the lowest point exposed of the stud, and the cutting region is not impeded by the cutter blade body reaching the datum plane.

The cutting force exerted on the stud, and reaction thereto is inclined at angle ss to the datum plane and surface 11 such that there is a force component tending to lift the body and cutter blade thereby putting a lateral (vertical) force on the tapered portion. Accordingly the angle of taper and the straight centre portion 47 are chosen to optimise both the cutting efficiency and strength of the blade.

It is found, at least with steels employed in threaded studs.

that when the cutting region has penetrated the stud for about three-quarters of its diameter the stud shears such that the cutting region does not have to cross the aperture 20 completely.

A guard 50 may be provided on the body to prevent the free end of the stud from flying from the aperture.

It will be appreciated that such characteristic shearing of the stud is independent of its diameter and having regard to the distance across the aperture that the cutting region is required to travel, that is, approximately to a distance of one quarter of the stud diameter from aperture side 26, it will be seen from Figure 2 that having regard to the diameter of any stud to be cut the width of the straight centre portion should correspond to no more than the chord length 20" of the aperture as such a distance along the direction of cut of one quarter of the stud diameter from the side 26 of the aperture. However, as the width of such straight centre portion also requires to be of the same order of magnitude as the diameter of the stud the use of different widths of cutting region is preferred for different sizes of studs.

Furthermore, as such different stud diameters also require different blade displacements that are inversely related to the cutting force required from the drive means, a cutting blade, in combination with drive means having appropriate force/stroke characteristics may be selected with respect to a common body and aperture.

An aperture 20 of circular cross-section is convenient to manufacture and inherently provides supports for the stud or other object at a side opposite to the cutting blade but may require the compromises of the abo':e-outlined criteria in respect of the width of the substantially straight portion of the cutting region. If desired, the cross-sectional shape of the aperture may be chosen to permit further travel of a wider cutting region or the portions of the body each side of said other side 26 of the aperture at the opening 21 may be removed or relieved to permit further travel of the blade.

As indicated above the angled direction of the cutting force through the cutter blade causes components of forces and reaction perpendicular to the surface 11 such that the body 16 tends to lift and tilt about the point reacting against the stud. If such motion is restrained, the force of such restraint is carried by the tapered portion of the cutter blade.

To minimise the action of such forces on the blade it may be preferred to permit the body to lift and tilt, notwithstanding that this varies the effective angle of inclination of the passage throughout the cutting operation.

The cutting force on the stud due to region 32 is concentrated whereas the reaction thereto is spread over as much of the aperture wall as makes contact with the stud. If desired the reaction force may principally be concentrated at the opening of the aperture, which is in line with the blade longitudinal axis 25 and thus the cutting force, by means of protrusion, (not shown) from the aperture wall at side 26. Alternatively, (also not shown), the aperture 20 may be made with its longitudinal axis inclined with respect to the datum plane such that it increases the angle made with respect to the passage longitudinal axis 25.The effect of such inclination is to provide, at the opening of the aperture closest to the datum plane an effective reaction point against initial cutting of a stud producing orthogonally to the datum plane and thereafter, as the upper part of stud is permitted to deflect by the cutter blade penetrations, a diffused support along its wall that includes a vertical component against body lift.

Other changes and modifications may be made without departing from the invention. For instance, the drive means may be other than hydraulic, and the working face 17 of the body may be separated from the datum plane it defines. That is, a datum plan outside of the working face would result in the passage axis 25 intersecting the datum plane part way across the object receiving aperture, which may be appropriate if shearing of part of the object is relied upon, whereas a datum plane within the working face would result in the passage axis intersecting the datum plane beyond the object receiving aperture, which may be appropriate if tilting of the body is relied upon to effectively increase the angle 13 during cutting so that the final point of intersection is at the lowest point on the object cut.

The precise form taken by the upper taper surface 46 is open to variation as is the cross-sectional shape of the cutter blade body and passage.

The cutter is not restricted to cutting studs or bolts of uniform circular cross-section and may be employed for cutting other protruding elongate objects, such as plain bars or pipes of circular and other cross-sections.

Claims

1. A cutter for an elongate metallic object comprising (1) a body having (i) a working face defining a datum plane, (ii) an object-receiving aperture opening towards the working face, and (iii) a cutter blade passage opening adjacent the end of the aperture at one side of the aperture and having a longitudinal axis extending towards the side of the aperture opposite to said one side, (2) a cutter blade supported in, and movable along, the passage and terminating in a cutting region displaceable, by movement of the cutter blade, across said aperture, and (3) drive means operable to move the cutter blade along the passage in the direction of said longitudinal axis, the longitudinal axis of the cutter blade passage extending in a direction that is inclined with respect to the datum plane and intersects the datum plane towards the side of the aperture opposite to said one side, and the cutting region of the blade extending parallel to the datum plane and substantially through said longitudinal axis direction and comprising for its whole length the closest part of the blade to the datum blade.

2. A cutter as claimed in claim 1 in which the working face is coincidental with the datum plane.

3. A cutter as claimed in claim 1 or claim 2 in which the longitudinal axis of the cutter blade intersects the datum plane in line with said side of the aperture opposite to said one side.

4. A cutter as claimed in any one of the preceding claims in which object-receiving aperture opens at said datum plane.

5. A cutter as claimed in any one of the preceding claims in which said aperture has a longitudinal axis extending substantially perpendicular to said datum plane.

6. A cutter as claimed in any one of the preceding claims in which said object-receiving aperture comprises a through aperture.

7. A cutter as claimed in any one of the preceding claims in which said object receiving aperture comprises a cylindrical form of substantially circular cross-section.

8. A cutter as claimed in any one of the preceding claims in which the passage is inclined with respect to the datum plane at such an angle that the direction of the longitudinal axis intersects the datum plane substantially in line with said one side of the object receiving aperture.

9. A cutter as claimed in any one of the preceding claims in which the longitudinal axis of the passage is inclined with respect to the datum plane at an angle in the range 120 to 200.

10. A cutter as claimed in claim 9 in which the angle is approximately 150.

11. A cutter as claimed in any one of the preceding claims in which the object receiving aperture has a substantially circular cross-section.

12. A cutter as claimed in any one of the preceding claims in which the cutting region of the blade is shaped, in a plane parallel to the datum plane as a substantially straight centre portion with radiussed end portions.

13. A cutter as claimed in any one of the preceding claims in which the cutting region is defined by an end portion of the cutter blade tapering in thickness towards said cutting region substantially equally inclined with respect to said longitudinal axis.

14. A cutter as claimed in claim 13 in which the taper at the side of the longitudinal axis distal from said datum plane is shorter than at the side proximate the datum plane.

15. A cutter as claimed in any one of the preceding claims in which the drive means comprises a cylinder containing a piston and defining therebetween a fluid chamber responsive to fluid pressure therein to displace the piston with respect to the cylinder, one each of said piston and cylinder being secured to the body and the other coupled to the said cutter blade.

16. A cutter as claimed in any one of the preceding claims in which the cutter blade passage is of circular cross-section and the cutter blade has a cylindrical body part slidably contained therein.

17. A cutter for an elongate right cylindrical metallic object comprising a cutter as claimed in claim 10 when dependant on claim 6 in which the width of the cutter blade is between the maximum diameter of an object to be cut by the cutter and the diameter of the object receiving aperture and the width of said substantially straight centre portion of the blade cutting region is approximately equal to the chord length of a cross-section through the object at approximately three quarters of the way therethrough in the direction of cut.

18. A cutter as claimed in claim 17 in which the radiussed end portions of the blade correspond in curvature to the object receiving aperture.

19. A cutter for an elongate metallic object substantially as herein described with reference to, and as shown by, the accompanying drawings.

20. A cutter for an elongate metallic object comprising (1) a body having a flat working face comprising a datum plane, an object-receiving aperture opening to the working face and a cutter blade passage opening to the aperture adjacent the opening of the aperture to the working face and at one side thereof, the passage having a longitudinal axis extending in a direction that is inclined to the working face and intersects the datum plane substantially at the side of the aperture opposite to said one side, (2) a cutter blade supported in, and movable along, the passage and terminating in a cutting region displaceable, by movement of the cutter blade, across said aperture, and (3) drive means operable to move the cutter blade along the passage in the direction of said longitudinal axis.