GB2498722A

GB2498722A - Grinding process and apparatus for serrated cutting edges

Info

Publication number: GB2498722A
Application number: GB1201127.6A
Authority: GB
Inventors: Oliver Graham Garside; James Robert Kitching
Original assignee: DAKIN FLATHERS Ltd
Current assignee: DAKIN FLATHERS Ltd
Priority date: 2012-01-24
Filing date: 2012-01-24
Publication date: 2013-07-31
Anticipated expiration: 2032-01-24
Also published as: GB201201127D0; GB2498722B

Abstract

A process for grinding serrated cutting edges on a moving blank steel band comprises moving two cooperating grinding heads towards and away from the blank steel band, each grinding head carrying at least one grinding wheel. Each grinding head may comprise up to seven grinding wheels which may be driven independently at a closely controlled constant speed by an electric motor. The axes of the grinding wheels may be parallel with the axis of the blank steel band. The travel of the grinding wheels towards the blank steel band and the time the wheels remain in any one position determine the shape of the serrations. The serrated cutting edge may be formed in a single pass. The grinding heads may be moved independently by servo motors and controlled by computer. The cutting edges may be formed on a knife or a saw. Also disclosed is a serrated cutting edge characterised by flattened out gullet bottoms and flattened tips (fig. 5), the edge being advantageous for cutting foam and similar stiff, low resistance materials.

Description

One pass grinding machine, process for obtaining a ground cutting edge and cutting edge thereby obtained.

This invention concerns the process of producing cutting edges on steel band blanks, especially serrated cuffing edges, a machine to produce such cuffing edges and a cuffing edge produced by that process on that machine.

The traditional process of producing serrated cuffing edges usually requires two or three operations. The first is to stamp out the shape of the serration of the blade edge followed by producing the cutting edge by grinding either one face only or both faces depending on the specific purpose of the knife or saw. A third operation may be polishing the ground edge to create a smooth finish on the blade. The steel band is delivered on large rolls which arc fed into a stamping machine to create the basic shape of the serration. Since the stamping is a step by step process requiring the band feed to stop and start. After a whole roll of band is processed, the steel band with the shaped edge is then transferred to a grinding machine.

The grinder is set to a specific paffem and can only be changed at the end of each complete batch of specific serration has been achieved.

Our new and improved grinding machine will perform the whole process in a "one pass" operation, avoiding the step by step method required with the classical grinding machines.

Our grinding machine operates with two grinding heads, each of which can carry can take up to seven grinding wheels. For most edge shapes three wheels per head is the usual arrangement.

However, for more complex edge shapes and for higher production rates more than three wheels per head are used. The grinding wheels are arranged to rotate, usually at a constant speed, in a plane transverse to the direction of travel of the steel blank. The heads move towards and away from the blank as they grind the shape of the tooth. With the blank being pulled past the rotating grinding wheels, the shape of the teeth is determined by the speed of the head movement towards or away from the blank, the time the heads stay in any one position and the distance the heads move towards or away from the blank. The parameters of the head movements are controlled by micro-processor and can be adjusted infinitely to any setting within a range limited only by the construction of the machine.

The grinding heads are arranged on opposite sides of the blank enabling two different processes to take place on the same machine without major resetting of the machine. For knives with a single sided ground edge, two blanks can be fed through the machine simultaneously and each of the Iwo heads grinds one of the blanks, each from the side on which the respective head is situated. For double-floe ground knives, the two heads work simultaneously on the same blank The heads are offset in the direction of the travel of the knife (or saw) blank to avoid the wheels interfering with each other when grinding the gullet of the serration, at which point part of the grinding wheel will protrude beyond the blank.

For example, in figure 2, the left hand head and its grinding wheels has reached the point in the grinding process when it starts to produce the serration. Until the whole of the gullet is shaped, the upper -of the wheel will be protruding to the right of the blank being processed. In order to be able to grind the opposite face of the blank in the same pass, the grinding wheels of the right hand head are placed staggered in the direction of the feed with respect to the grinding wheels on the left hand head.

The grinding wheels are tooth-belt driven by precision geared electric motors to ensure steady speed for the grinding wheels and reduce the chance of speed reduction whcn the grinding pressure increases during the process. The motors are fixed to the slides on which the heads travel to ensure constant tension on the driving belts.

The slide movement is achieved by servo motors controlled on CNC (computer numeric controlled) axis for absolute accuracy of movement to the heads. Wheel configuration can be varied according to requirements from two per head to six or even seven.

The edge creation proceeds as follows. The steel blank is fed in or pulled through the guide on the machine. The blank guide is situated in between two grinding heads. With the blank orientated vertically, the heads are arranged in a horizontal relationship with the position of the blank, such that a horizontal movement of the heads will result in a contact with the blank.

The process to create one tooth of the inventive serrated edge consists of three separate steps, all in one continuous operation with the blank moving past the grinding wheels without slowing or stopping.

Step (1) is moving the heads to the maximum programmed distance towards the blank and holding it there for a predetermined time (grinding the gullet).

Step (2) is to retreat the heads gradually to the predetermined minimum distance and holding them there for a different predetermined time (producing the tip).

Step (3) is the gradual reapplication of pressure to move the heads to their programmed maximum working distance and holding them there, again for the first mentioned predetermined time (creating the second gullet).

Because the machine is constructed in such a way that the relative geometry between the various operative parts is variable to a high degree, the number of types and shapes of achievable serrations is immense. This versatility combined with total computer control, makes our machine and our process highly competitive and efficient. It can produce as much as 180 mm per second of serrated edge of any configuration.

As said here above, any conceivable type of blade edge can be produced with this machine.

The two faces could be ground to a different extent, for example, with one face hollow ground and the other flat ground. The gullet can be stretched or contracted, gullets can deeper or shallower and tips can be long points or short stumps. All possible shapes form part of this invention, as long as they are produced by our machine.

However, the preferred shape of serration produced by this process and forms on such a machine is shown in figure 5. The blade is double (both faces) hollow ground, has a flat bottomed gullet and flattened serration tips. This configuration is advantageous for efficient cufting of foam and similar stiff low resistance materials.

The invention will be described in greater detail by means of reference to the drawings.

Figure 1 shows a schematic 3 dimensional view of the grinding machine used to realise the invention.

Figure 2 shows the same machine in front elevation.

Figure 3 shows a three wheeled grinding head creating a cutting edge.

Figure 4 shows one grinding head turned through 90° relative to figure 3.

Figure 5 shows a piece of band knife with the preferred serration Figure I shows schematically the construction of the grinding machine. Two grinding heads are mounted side by side with their axes parallel to each other. The axes have grinding wheels mounted at the forward end, as shown in the figure. The wheels are belt driven by electric motors, one for each head. The heads and motors are mounted on slides that move the heads perpendicular to the grinding wheel axes. Those slides are activated by precision hydraulic motors for high precision step-less movement which in turn is controlled by micro processors.

Figure 2 is a stripped down representation of the machine sccn from in front The front pair of grinding wheels is shown with the blank feeder guide in between the wheels. The arrows at the bottom of the figure indicate the movement of the slides carrying the grinding heads.

Needless to say, the two heads are independently driven and can be operated separately or simultaneously.

Figure 3 shows the grinding wheels grinding the serrations in to the blank. The blank is pulled from left to right in this figure and the grinding wheels are pushed towards or pulled away from the blank, depending on which part of the serration is being ground. In this figure the movement of the grinding heads is perpendicular to the plane of the paper.

Figure 4 shows the grinding process at two critical points. The left hand part shows the gullet being ground and the right hand -shows the tip being ground. And finally, figureS shows a strip of the final product in its preferred form.

Claims

<claim-text>Claims: A process for grinding serrated cuffing edges onto a blank steel band wherein two grinding heads, carrying at least one grinding wheel each, cooperate by moving towards and away from said blank steel band.</claim-text> <claim-text>2. A process for grinding serrated cuffing edges onto blank steel band wherein each grinding head carries a set of up to seven grinding wheels.</claim-text> <claim-text>3. A process for grinding serrated cuffing edges according to claims I to 3 wherein each set of wheels is driven at a closely controlled constant speed.</claim-text> <claim-text>4. A process for grinding serrated cuffing edges according to claims I to 3 wherein each set of wheels is driven by its own electric motor.</claim-text> <claim-text>5. A process for grinding serrated cuffing edges according to claim I and 2 wherein the axes of the grinding wheels are aligned parallel to said blank steel band.</claim-text> <claim-text>6. A process for grinding scrratcd cutting edges according to claimsito 3 whcrcin the shape of the serrations is dctcrmined by the distance of travcl of the grinding wheel into the blank and by the time it remains in any one position.</claim-text> <claim-text>7. A process for grinding scrratcd cutting edges according to any one of the preceding claims wherein the movement of the grinding heads is achieved by servo motors which are controlled on CNC axes.</claim-text> <claim-text>8. A process for grinding serrated cuffing edges according to any one of the preceding claims wherein the said serrated cuffing edge is finished in one pass.</claim-text> <claim-text>9. A process for grinding serrated cuffing edges according to any one of the preceding claims wherein said cutting edges are formed as knife or saw edges.</claim-text> <claim-text>10. A grinding machine for carrying out the process according to claims I to 9 wherein serrated cuffing edges are ground into a moving blank steel band, comprising two grinding heads cquippcd with at least onc grinding wheel each, which grinding wheels arc movcd towards and away from said moving blank steel band to grind thc said serrations.</claim-text> <claim-text>11. A grinding machine according to claim 10 wherein each of said grinding heads moves independently of the other towards or away from said blank.</claim-text> <claim-text>12. A grinding machine according to claim 10 and 11 wherein each head can carry up to seven grinding wheels.</claim-text> <claim-text>13. A grinding machine according to claim 10 to 12 wherein each set of said grinding wheels is driven separately by and electric motor.</claim-text> <claim-text>14. A grinding machine according to claim 10 wherein the shape of the serrations is determined by the distance of travel of the grinding wheel into the blank and by the time it remains in any one position.</claim-text> <claim-text>15. A grinding machine according to claim 10 wherein the final shape of the cutting edgc is achieved in one single pass of the blank through the machine.</claim-text> <claim-text>16. A grinding machine according to any one of the preceding claims, wherein the grinding operations are computer controlled.</claim-text> <claim-text>17. A serrated cutting edge produced by the process according to claims 1 to 9.</claim-text> <claim-text>18. A serrated cutting edge according to claim 17 which shows flattened out gullet bottoms and flattened tips.</claim-text> <claim-text>19. A serrated cutting edge according to claim 18 which is produced and finished in one single pass through the said grinding machine.Amendment to the claims have been filed as follows Amended Claims: 1. A process for grinding serrated cutting edges onto a continuously moving blank steel band wherein two grinding heads, carrying at least one grinding wheel each, cooperate by moving towards and away from said moving blank steel band.
2. A process for grinding serrated cutting edges onto a continuously moving blank steel band according to claim I, wherein each grinding head carries a set of up to scven grinding wheels.
3. A process for grinding serrated cuffing edges according to claims I and 2 wherein each set of wheels is driven at a closely controlled constant speed.
4. A process for grinding serrated cuffing edges according to claims I to 3 wherein each set of wheels is driven by its own electric motor.
5. A process for grinding serrated cutting edges according to claim 1 and 2 wherein the (0 axes of the grinding wheels arc aligned parallel to said continuously moving blank steel C band.
6. A process for grinding serrated cutting edges according to claims 1 to 3 wherein the r shape of the serrations is determined by the distance of travel of the grinding wheel into the continuously moving blank and by the time it remains in any one position.
7. A process for grinding serrated cuffing edges according to any one of the preceding claims wherein the movement of the grinding heads is achieved by servo motors which are controlled on CNC axes.
8. A process for grinding serrated cuffing edges according to any one of the preceding claims wherein the said serrated cutting edge is finished in one pass.
9. A process for grinding serrated cuffing edges according to any one of the preceding claims wherein said cutting edges are formed as knife or saw edges.
10. A process for grinding serrated cuffing edges according to any one of the preceding claims wherein said cutting edges are formed with flattened out gullet bottoms and flattened tips.II A grinding machine for carrying out the process according to claims I to 10 wherein serrated cuffing edges are ground into a moving blank steel band, comprising two grinding heads equipped with at least one grinding wheel each, which grinding wheels are moved towards and away from said continuously moving blank steel band to grind the said serrations.12. A grinding machine according to claim 11 wherein each of said grinding heads moves independently of the other towards or away from said blank.13. A grinding machine according to claim 11 and 12 wherein each head can carry up to seven grinding wheels.14. A grinding machine according to claim 11 to 13 wherein each set of said grinding wheels is driven separately by and electric motor.15. A grinding machine according to claim 11 wherein the shape of the serrations is determined by the distance of travel of the grinding wheel into the continuously moving blank and by the time it remains in any one position.16. A grinding machine according to claim 11 wherein the final shape of the cutting edgc (0 is achicvcd in onc single pass of thc blank through the machine.17. A grinding machine according to any one of the preceding claims, wherein the grinding operations arc computer controlled. r</claim-text>