WO2012033540A2

WO2012033540A2 - Enhanced power compact bolt cutter

Info

Publication number: WO2012033540A2
Application number: PCT/US2011/001576
Authority: WO
Inventors: Michael H. Panosian; James Stobar; Josh Keeler
Original assignee: Panosian Michael H; James Stobar; Josh Keeler
Priority date: 2010-09-10
Filing date: 2011-09-12
Publication date: 2012-03-15
Also published as: WO2012033540A3

Abstract

An enhanced power compact bolt cutter or the like includes a pair of levers pivoted relative to each other to form opposing cutting jaws to one side of a pivot point and actuating arms to the other side of the pivot point. The actuating arms are greater in length than the lengths of the cutting jaws to provide a first mechanical advantage M1 in transmitting forces applied to the actuating arms to the cutting jaws. A pivotally mounted handle can be gripped and actuated by a user in a repetitive ratcheting motion to drive a smaller gear. A gearbox includes the driven smaller diameter gear or pinion for driving a larger diameter gear. A cam is coupled to the larger diameter gear to share common rotational motions with the larger diameter gear. Using the smaller diameter gear to drive the larger diameter gear provides a second mechanical advantage M2 so that the total mechanical advantage for transmitting forces from the handle to the jaws is M=M1x M2. Instead of cutting edges on the jaws other functional members can be used such as crimping elements or the like.

Description

ENHANCED POWER COMPACT BOLT CUTTER

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to hand and power tools and, more specifically, to an enhanced power compact bolt cutter.

2. Description of the Prior Art

Cutting bolts, steel rods and other hard workpieces requires the use of tools that exhibit significant mechanical advantages since the forces that are required to cut such items are substantially beyond the forces that can be manually applied by most if not all users.

Typically, in order to attain the mechanical advantages required to cut bolts or the like bolt cutters use shear-type cutters that use two pivoted levers that have relatively short, stubby cutting jaws on one side of the pivot while having long handles on the other side of the pivot. The mechanical advantage offered by such shears is the ratio of the lengths of the long handles in relation to the lengths of the short cutting jaws. Clearly, in order to enhance mechanical advantage with such tools the handles are frequently made long and increase in length as the cutting power needs to be increased. While some such bolt cutters have extremely long handles, reaching some several feet long, there are practical limits. The most obvious limitation is storage, as such bolt cutters cannot be carried on a tool belt or even included in standard toolboxes. Also, as the handles become very long the weight of the tool increases and using the tool becomes inconvenient and unwieldy. SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a bolt cutter that does not have the disadvantages inherent in known bolt cutters.

It is another object of the invention to provide a bolt cutter that is compact and yet provides a significant mechanical advantage.

It is still another object of the invention to provide a bolt cutter that, for its size, provides increased cutting power as a result of enhanced mechanical advantage.

It is yet another object of the invention to provide a bolt cutter that is simple and convenient to use.

It is a further object of the invention to provide a bolt cutter of the type under discussion that provides a significant mechanical advantage while it can be carried on a tool belt or in a standard-sized toolbox.

Is still further object of the invention to provide a bolt cutter as in the previous objects that allows a user to cut bolts and other hard stock with a compact hand and/or power tool.

In order to achieve the above objects, as well as others that will become apparent hereinafter, an enhanced power compact bolt cutter in accordance with the present invention comprises a pair of levers pivoted relative to each other to form opposing cutting jaws to one side of a pivot point and actuating arms to the other side of said pivot point. The actuating arms are greater in length then said cutting jaws to provide a first mechanical advantage M1 in transmitting forces applied to said actuating arms to said cutting jaws. Handle means a provided for gripping and actuation by a user. Gear means providing a second mechanical advantage M2 couple said handle means to send actuating arms, whereby the total mechanical advantage from transmitting forces from said handle means through said cutting jaws is M=M1xM2. The invention also contemplates the use of an electrical motor driving the gear mechanism instead of the handle means so that a user can apply enormous forces as the cutting jaws by simply actuating a switch that drives the motor and gear mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

Those skilled in the art will appreciate the improvements and advantages that arise from the present invention upon reading the following detailed description, claims and drawings, in which:

Fig. 1 is a perspective view of an enhanced power compact bolt cutter in accordance with the present invention, shown in its cutter jaws closed position;

Fig. 2 is a side elevational view of the bolt cutter shown in Fig. 1 ;

Fig. 3 is a side elevational view of the bolt cutter shown in Figs. 1 and 2, showing the other side of the tool and the relative movements of the mechanical parts to enhance the cutting power of the tool;

Fig. 4 is a lower perspective view of the bolt cutter shown in Fig. 1 with the cover of the gearbox removed to show the gear mechanism for enhancing the power of the tool while minimizing the lengths of the handles;

Fig. 5 is a side elevational view of the bolt cutter shown in Fig. 4; Fig. 6 is similar to Fig. 3 with part of the housing removed to illustrate the manner in which the gear mechanism imparts a force to the cutting levers by means of a cam;

Figs. 7a-7d are side elevational views of an alternate embodiment of the compact bolt cutters showing different optional positions of the handles;

Fig. 8 is an enlarged side elevational view of the bolt cutter of Figs. 7a-7d showing the additional feature for adjusting the gear ratio;

Figs. 9 and 10 are opposite side elevational views of another embodiment of the compact bolt cutters in which the cam is driven by a motor instead of being driven manually;

Fig. 11 is a perspective view of the internal components of the bolt cutter of Figs. 9 and 10, showing the details on the cam side of the drive;

Fig. 12 is similar to Fig. 11 but showing the gear side of the drive;

Fig. 13 is a perspective view still another embodiment of the bolt cutter showing the battery pack for energizing the motor drive and replaceable cutting blades on the cutting jaws;

Figs. 14 and 15 are side elevational and perspective views, respectively, of the bolt cutter shown in Fig. 13 with the cutting blades removed or separated from the cutting jaws; and

Fig. 16 is a perspective view of yet another embodiment of the bolt cutter that has a long neck between the cam drive and the cutting jaws at a remote end of the tool and handle supporting the battery pack and the motor drive at a proximate end. DESCRIPTION OF PREFERRED EMBODIMENT

Referring now specifically to the figures, in which identical or similar parts are designated by the same reference numerals throughout, and first referring to Figs. 1 and 2 an enhanced power compact bolt cutter in accordance with the present invention is generally designated by the reference numeral 10.

The bolt cutter 10 includes a fixed support plate 12 that has a proximate portion 12a that forms part of a handle 12a, a mid-portion 12b and a forward or remote portion 12c. A fixed lever 14 has a fixed jaw 14a formed with a cutting edge of 14c. A movable lever 16 includes a jaw 16a with a cutting edge 16c and a lever arm 16b. The fixed lever 14 is secured to the support plate 12 in any suitable manner, while the movable lever is pivotally mounted on a pair of pivot plates 18a, 18b arranged on opposite sides of the jaws and secured by bolts 20, 22 that also serve as pivot pins.

Referring to Figs. 1 and 2, shown in phantom outline is a workpiece W, such as a metal rod or the like, indicating a typical or optimum position for such a workpiece while being cut. The length or distance L1 is between the positions of the bolts 20, 22 and the typical position of the workpiece, while the length or distance L2 is between those bolts and the end of the lever arm 16b, together defining a first mechanical advantage M1 =L2/L1. As indicated, the distance or length L2 is normally maximized in traditional bolt cutters to enhance the mechanical advantage. However, with the bolt cutter 10 of the present invention the length L2 can be maintained relatively small since the mechanical advantage M1 only provides a part of the mechanical advantage of the overall tool, as will be described.

In order to enhance the mechanical advantage of the bolt cutter 10 it is provided with a gearbox 24 that includes a housing 24a and a cover 24b.

Referring to Figs. 4-6, a large diameter gear 26 is mounted for rotation about a bolt 28 that also serves as a pin or axle. A ratcheting mechanism 32 is connected to the housing 24a and includes a small diameter gear 30 that can be selectively rotated about a bolt 33 that also serves as a pivot or axle about which a movable arm 32' can be pivoted. The small diameter gear 30 is meshed with the large diameter gear with the teeth of such gears being engaged with each other as best shown in Fig. 6. As is well known, the mechanical advantage of a set of meshed gears of different diameters is the ratio of those diameters. Thus, when the small diameter gear is manually driven or actuated in order to rotate or drive the larger diameter gear a second mechanical advantage M2=D2/D1 is achieved, where D2 is the diameter of the larger diameter gear 26 and D1 is the diameter of the smaller diameter gear 30. The mechanical advantage can also be expressed as the ratio of the number of teeth in the larger gear to the number of teeth in the smaller gear, where the smaller gear is the pinion gear while the larger gear is the driven gear.

As is known, the total or composite mechanical advantage when two mechanical advantages are involved is the product of the two mechanical advantages. Thus, with the bolt cutter 10 the total mechanical advantage is M= Mix M2. It will be appreciated that while spur gears are shown any gear

mechanisms may be used that are compact and provide mechanical advantage. Thus, is also possible to use external or internal gears, helical, bevel, crown, worm, a noncircular, rack and pinion or the like.

The larger diameter gear 26 is fixed to a cam 34 on the axle or bolt 28 so that both the large gear 26 and the cam 34 share rotational movements. A roller 36 is mounted on a bearing 38 provided at the free end of the lever 16b, the roller 36 being arranged to engage and follow the cam surface or edge 34'. To maintain the roller 36 on the handle 12a a member 40 having a free arcuate portion 40' is configured and arranged to engage and urge the a roller 36 downwardly, as viewed in Fig. 6, to normally urge the jaw 16 to rotate in a counterclockwise direction, as viewed in Fig. 6, to thereby separate the cutting edges 14c, 16c when permitted to do so by the cam 34. When the cam 34 is positioned so that the roller 36 engages the region 34a having the smallest diameter the cutting jaws or edges 14c, 6c are pivoted to points of maximum separation. However, repeated actuations of the handle or movable arm 32' and rotations in the direction ml causes the driven, smaller diameter gear 30 to rotate in a clockwise direction m2, as viewed in a Fig. 3. By successively repeating actuations and movements of the handle movable arm 32', the rotations of the small gear 30 are transmitted to the larger gear 26. Although the larger gear will rotate more slowly than the rotation of the smaller gear 30 these motions impart a greater torque to the larger gear. The rotation of the larger gear 26 will, in turn, rotate the cam 34 in a counterclockwise direction as viewed in Fig. 3, gradually moving portions of successively larger diameter against the roller 36 of the cam until the larger diameter portion 34b forces the roller 36 to move to its radially outwardly maximum position thereby causing the jaws or cutting edges 14c, 16c to close and come into contact as shown in Fig. 6.

The gear box or housing 24a is preferably a closed and sealed housing by tightening the fasteners or screws 42. Suitable lubricants can be provided within the gearbox to minimize friction and that, therefore, maximize the forces applied to the jaws 14, 16.

It will be appreciated that while the handle or movable arm 32' will need to be pulled a number of times before the cutting edges 14a, 16a close together, significantly higher forces will be transmitted to the cutting jaws opposed to the forces manually applied by a user to the handle 12a and movable arm 32'.

After the cutting action has been completed, after the roller 36 is forced outwardly by the high cam portions 34b, continued actuation of the handle

32'causes continued rotation of the cam in direction m3 as shown in Fig. 3. Once the cam is moved beyond the position generally shown in Fig. 6 and the edge or step 34c passes the roller the biasing arm 40 causes the movable lever 16 to rotate in a counterclockwise direction as viewed in Fig. 6 when the roller 36 moves down the step 34c from the high point 34b to the low point 34a. Once the jaws are separated by the biasing member 40 the bolt cutter 10 is again ready for another cutting operation. It will be appreciated that the mechanism described can also be used to increase the mechanical advantage of other hand tools including, but not limited to, pruners, cable cutters, crimpers, etc.

Referring to Figs. 7a-7d another embodiment of the bolt cutter is shown that has the ability to change the relative angular orientations of the handles and the directions of the cutting jaws. In Fig. 7a the handles are generally in-line with the direction of the cutting blades or jaws, and Fig. 7b shows the handles separated prior to being manually moved to the fixed handle to drive the gears and the cam as described. In Fig. 7c the handles are shown displaced

approximately 90° from the positions shown in Fig. 7a, and Fig. 7d shows the handles separated as in Fig. 7b. The nature of the cutting job and the space considerations dictate the positions of the handles in any given application.

However, once the handles are locked in place repeated actuation of the handles causes the gears and the cam to move as described.

In Fig. 8 an enlarged side elevational view of the bolt cutters of Figs. 7a-7d is shown, also showing detail of gear ratio adjustment lever 46 that allows a user to change the gear ratio from any one of three different ratios. It will be evident to those skilled in the art that the specific ratio options are not critical and may be selected for any given application. It will be clear, however, that the selected gear ratio will also dictate both the speed at which the cutting jaws close and thus cut the work as well as the force that the user will need to apply to the handles- these being inversely related. The less force to be applied the higher the gear ratio and the slower the cutting action. The present invention can also be used with a motorized drive so that repeated actuations of the handles is not necessary. Referring to Figs. 9-12 the cutting components and gear drive are shown. However, instead of the handles actuating the gears and cam a motor 50 has a shaft 52 at least a portion of which is provided with a worm gear 54. The gear 54 is coupled to gear 56 that drives a larger diameter gear 26 by means of gear 30 mounted on the same shaft as the gear 56 and fixed to share the rotations thereof. The motor is connected to a source of energy, such as a battery pack, through a switch in a conventional manner. The switch can be arranged on the handle so that it can be conveniently engaged by a finger of the user when the motor is to be energized. As with the manual version rotation of the gears actuates the cam 34 that, in turn, controls the angular position of the movable jaw relative to the fixed jaw. Suitable biasing means, such as a spring (not shown) can be used to re-open the jaws after the cutting operation when the cutting jaws are brought into contact with each other and the motor is energized to move the cam beyond the high point 34b.

In Figs. 13-15 another embodiment is shown the operation of which is the same as previously described. An elongate handle 60 is provided that serves as a handle during use, with a battery pack 62 being mounted at one end of the handle while the previously described motor drive is provided. The motor can be housed within the handle 60 to actuate the drive including gears and cam as aforementioned. An ergonomically positioned trigger switch 64 closes the circuit by applying the battery voltage to the motor when the motor is to be energized. In Figs. 14-15 the cutting jaws are provided with means to replace worn or damaged cutting blades. Thus, the jaws 70, 72 are configured to receive blades 74, 76 that can be secured to the jaws by means of set screws 78 received within holes 80, 82. Preferably, to insure proper alignment and optimal positioning of the cutting blades grooves 84 are provided in the surfaces of the jaws facing each other. Tongues 86 are dimensioned to be received within the grooves 84 to facilitate alignment and insertion of the set screws.

A still further embodiment is shown in Fig. 16, in which the gears and cam are provided at a remote end of an elongated neck 90. At the proximate end a pistol-type handle includes the trigger switch, the battery pack and the motor drive. However, since the motor drive is spaced from the gears located at the other end, an elongated rod or shaft 92 is coupled to the drive motor, or is an extension of the motor shaft, i.e. a long motor shaft that extends the length of the neck 90. The elongated rod or shaft drives the equivalent of gear 56 shown in Fig. 12. The unit shown in Fig. 16 is especially useful in cutting items near the ground, such a rebars, without the need of the user to bend down or work on his or her knees. The unit is also clearly useful in reaching other locations not normally reachable, such as overhead construction bars or rods.

In connection with all of the motor-driven units the speed of the motor as well as the gearing ratio is selected to cause to close in approximately 4 seconds. Clearly, this is not critical and other criteria can be used. As aforesaid, if quicker closings are desired the motor speed can be increased or the gear ratio changed. It is contemplated that the gears be made of carbon steel while the cutting blades of chromium molybdenum (CrMo). The design criteria may be based on the power applied by 24" bolt cutters-this dictating the forces to be applied that, in turn, dictate the other electrical parameters of the motor and the gear ratios.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes won't readily occur to those skilled in the art, it is not designed to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents

may be resorted to, falling within the scope of the invention.

Claims

CLAIMS:

. Enhanced power compact bolt cutter comprising

a pair of levers pivoted at intermediate positions to form opposing cutting jaws with opposing cutting edges to one side of the pivot point and actuating arms to the other side of the pivot point, said actuating arms having end portions spaced remotely from said pivot point a distance greater than the distance of said cutting jaws from the pivot point to provide a first mechanical advantage M1 for transmitting forces applied to said actuating arms to said cutting jaws;

handle means for gripping and actuation by a user; force enhancing means coupled to at least said one of said lever end portions for providing a second mechanical advantage M2 when a force is transmitted by a user through said handle means to said at least one of said actuating arms and to said cutting jaws,

whereby the total mechanical advantage for transmitting forces from said handle to said cutting jaws is equal to M = M1 x M2.

2. Enhanced power compact bolt cutter as defined in claim 1 , wherein said handle means comprises a fixed handle and a movable handle that can be manually reciprocated between positions proximate to and spaced from said fixed handle by drawing said handles together and releasing said movable handle relative to said fixed handle, respectively, said force enhancing means being responsive to reciprocating movements of said handles to create the mechanical advantage M. Enhanced power compact bolt cutter as defined in claim 2, wherein said force enhancing means includes a gear reduction system in which said movable handle actuates rotation of a first gear having a diameter D1 , a second gear having a diameter D2 being in meshed engagement with said first gear, wherein D2/D1>1 to reduce the speed of rotation of said second gear in relation to said first gear, and

cam means including a cam mounted for rotation with the rotation of said second gear and a cam follower linked to a movable actuating arm to selectively urge it to move the cutting edges closer together or further apart.

Enhanced power compact bolt cutter as defined in claim 3, wherein said second gear and cam are mounted for rotation therewith about a cam axis, said cam radial dimension gradually and increasingly increasing from a minimum first radial distance and a maximum second radial distance before rapidly dropping again to said minimum first radial distance, said cam follower causing said cutting jaws to come together when said cam is caused to move along said cam from said minimum distance when said cutting jaws exhibit maximum spacing for receiving a work to said maximum distance when said cutting jaws substantially abut against each other for cutting the work, additional rotation of said cam causing said cam follower to drop to said minimum distance to re-open said cutting jaws to ready the bolt cutter to receive another work to be cut.

Enhanced power compact bolt cutter as defined in claim 1 , wherein said levers are at spaced pivot points to cause said cutting jaws to move in relation to each other in directions opposite to the relative motions of said actuating arms, whereby movement of said actuating arms together causes said cutting jaws to separate and separating said actuating arms causes said cutting jaws to draw closer together.

Enhanced power compact bolt cutter as defined in claim 3, further comprising ratchet means coupled to said first gear and movable handle to enable said first gear to continuously rotate in the same direction with reciprocating movements of said movable handle. Enhanced power compact bolt cutter as defined in claim 3, further comprising a cover or housing to enclose said gear reduction system; and lubricating means within said housing to lubricate said gears.

Enhanced power compact bolt cutter as defined in claim 1 , wherein said cutting jaws are generally arranged along a predetermined direction and said handles are arranged along a direction generally coextensive with said predetermined direction.

9. Enhanced power compact bolt cutter as defined in claim 1 , wherein said cutting jaws are generally arranged along a predetermined direction and said handles are arranged along a direction generally parallel with said predetermined direction.

10. Enhanced power compact bolt cutter as defined in claim 1 , wherein said cutting jaws are generally arranged along a predetermined direction and said handles are arranged along a direction generally normal with said predetermined direction.

11. Enhanced power compact bolt cutter as defined in claim 1 , wherein said cutting jaws are generally arranged along a predetermined direction, and further comprising adjustment means for modifying the angular orientation of said handles relative to said

predetermined direction.

12. Enhanced power compact bolt cutter as defined in claim 3, wherein said gear reduction system is adjustable for selecting one of a plurality gear ratios for cutting a work.

3. Enhanced power compact bolt cutter comprising

force enhancing means coupled to at least said one of said lever end portions for providing a second mechanical advantage M2 when a force is transmitted by a user through said handle means to said at least one of said actuating arms and to said cutting jaws, whereby the total mechanical advantage for transmitting forces from said handle to said cutting jaws is equal to M = M1 x M2; and

drive means for driving for drive said force enhancing means.

14. Enhanced power compact bolt cutter as defined in claim 13,

wherein said drive means comprises an electrical power drive.

15. Enhanced power compact bolt cutter as defined in claim 14,

wherein said electrical power drive includes an electrical motor.

16. Enhanced power compact bolt cutter as defined in claim 15,

wherein said electrical motor is coupled to said force enhancing means by means of a worm screw drive.

17. Enhanced power compact bolt cutter as defined in claim 14,

wherein said electrical power drive is powered by a portable battery.

18. Enhanced power compact bolt cutter as defined in claim 13,

wherein said cutting jaws comprise replaceable cutting edges.

19. Enhanced power compact bolt cutter as defined in claim 13,

wherein said cutting jaws and said force enhancing means are remotely spaced from said drive means by means of a hollow tubular member to which both said force enhancing means and said drive means are mounted and a drive shaft or rod extending through said hollow tubular member for mechanically coupling said drive means to said force enhancing means.

Enhanced power compact bolt cutter as defined in claim 19, further comprising a hand grip on said hollow tubular member to facilitate holding and handling the bolt cutter when cutting a work remotely when holding said drive means proximately to the user.