The present invention relates to a manually operated shearing machine-, driven by a conventional drill and intended for shearing sheet-metal with thicknesses up _t » to about 5 mm, said machine comprising a body provided

5 with support wheels, two cutting wheels cooperating with each other on the body, the sheet-material being sheared between the cutting edges thereof, one of said wheels being driven and the other rotating with the sheet-material being cut.

10 As accessory to relatively powerful hand drills, machines of the type described are intended to fill a gap between all small hand tools which can really only be used for thin-gauge sheet-material, and large machines which are expensive to purchase and are per-

15 manently anchored in the workshop floor.

The object of shearing machines of this type is to enable both straight and curved cuts of unlimited length to be effected simply and quickly.

However, it has been found that cutting curved sheet- 20 metal cuts is not entirely devoid of problems when attempted with conventionally arranged cutting wheels. There is resistance to the curve, which leads to uneven cuts. i

The object of the present invention is to eliminate 25 these problems and provide a means permitting uniform, clean edges to be easily achieved when shearing both straight and curved cuts. Furthermore, the arrangement according to the invention shall be so designed that by simple and quick adjustment the shearing wheels

achieve the correct position in relation to each other.

This is achieved with the machine according to the pre¬ sent invention, the essential novelty being that the cutting wheels are arranged obliquely at an angle o to the normal plane of the sheet-material to be sheared and that the free side surfaces of the shearing wheels are bevelled close to the shearing edges at the same angle c , forming peripheral surfaces, the shearing wheels being so arranged in relation to each other that said peripheral surfaces lie in the same plane and form a nip.

The inclination of the shearing wheels offers consider¬ ably better turning ability so that uniform, clean cuts can be achieved, even by an inexperienced operator.

Bevelling of the free side surfaces of the cutting wheels with said angle ° , gives peripheral surfaces bounding on the shearing edges, said surfaces lying in the normal plane to the sheet-material to be cut. Thus, after sharpening of the cutting edges, any adjustment of the mutual position of the shearing wheels necessitated can be achieved by a simple vertical adjustment. The axle of the lower shearing wheels may thus suitably be se¬ cured by means of an eccentric fixed mounting.

According to a preferred embodiment of the invention the angle -K is approximately 3 .

Additional advantages and characteristics will be re¬ vealed in the following claims and in the following de¬ tailed description with reference to the accompanying drawings in which

Figure 1 shows a side view of the sheet-material

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shearing machine according to the invention.

Figure 2 shows a front view of the sheet-material shearing machine according to Figure 1 , and

Figure 3 shows a detailed enlargment of the shearing 5 machine wheels at the nip.

The drawings show a shearing machine according to the in¬ vention, comprising a body 1 , in turn comprising a first upper, vertical section 2, a second lower, vertical sec¬ tion 3 and an intermediate horizontal section 4. The 10 upper and lower body sections are laterally displaced in relation to each other. The body is manufactured in one piece, by casting, for instance, or by welding together the three body sections in order to obtain a robust con¬ struction.

15 The shearing machine also comprises shearing members con¬ sisting of two cooperating shearing wheels, one a driven shearing wheel 5 and the other a freely rotating or co- rotating shearing wheel 6, said wheels being located each in its own vertical plane and thus parallelly dis-

20 placed in relation to each other. The driven shearing wheel 5 is toothed, the tooth edges facing the direction of rotation. The driven wheel 5 is arranged on an axle journalled in the upper section 2 of the body. The freely rotating wheel 6 is journalled on an axle, mounted in the

25 lower body section 3 preferably by means of an eccentric fixed mounting. The axles are parallel and located at a predetermined distance from each other dependent on the diameters of the shearing wheels 5,6. Furthermore, the axles are rigid, i.e. have fixed journalling both axially

30 and radially. The design of the body as a single, sturdy construction contributes to this fixation of the axles. The eccentric mounting of the lower axle, described above.

enables adjustment in radial direction to compensate for material losses when the cutting edges are sharpened.

Each shearing wheel 5, 6 has an inner face 10, 11 facing the body parts 2, 3 respectively, an outer face 12, 13 with free surface, and a radially outer surface 14, 15, respectively. The outer faces 12, 13 have greater dia¬ meter than the inner faces 10, 11 and the radially outer surfaces 14, 15 thus become bevelled.

According to the invention the shearing wheels 5 and 6 are inclined in relation to the vertical plane, at an angle of C . This is to facilitate manoeuvrability when shearing curved cuts. The peripheral edges of the wheel faces 12, 13 are bevelled at the same angle Z. to form peripheral angles 16, 17.

Thus, after sharpening the cutting edges, which is done from the radially outer surface, the lower shearing wheel 6, with its eccentric securing means, need only be ad¬ justed in vertical direction.

Cutting edges 18, 19 are formed between the radially outer surfaces 14, 15 and the peripheral surfaces 16, 17, respectively. The angle between the cutting edges shall preferably be less than 90 and the bevelling of the radially outer surfaces should therefore exceed the angle _ .

According to a preferred embodiment of the invention the angle °Sis about 3 . A suitable bevel for the radially outer surface is therefore approximately 5°.

To achieve efficient shearing it is important that the shearing edges 18, 19 must touch each other, and the peripheral outer parts 16, 17 of the outer faces 12, 13 of the shearing wheels therefore lie in the same plane.

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The nip 20 formed by the shearing wheels has thus no intermediate gap and the shearing wheels are therefore single-shearing. A single cutting groove or shearing cut is thus formed continuously when the shearing machine 5 passes over a sheet of metal, the sheet passing through the nip 20. This also results in there being no cuttings.

Thus, besides acting as connector between the upper and lower parts of the body, the intermediate horizontal part 4 also functions as a deflector and for this purpose is

10 constructed in the form of a wedge, the leading edge being situated in line with the nip 20 of the shearing wheels 5, 6, perpendicular to the direction of feed of the sheet-metal and spaced therefrom, i.e. slightly after said nip. The wedge-shaped deflector 4 has an upper and

15 a lower support surface, the upper support surface advan¬ tageously being coplanar with the shearing-wheel nip or contact point so that one of the separated pieces of sheet is carried to the upper supporting surface of the deflector, while the other separated piece of sheet will

20 be guided beneath the lower supporting surface of the de¬ flector.

The top shearing wheel may be driven by a reduction gear comprising a combination of a worm and gearing enclosed in the upper part 2 of the body. The reduction gear is connected

25 to or constructed on a drive shaft extending rearwardly from the body 1 to connect with the chuck of a conven¬ tional hand drill 21 as the power source. A bar 22 is secured to the body 1 and extends rearwardly therefrom. The bar functions as a drive-shaft lead-in and guide means

30 and is provided at its rear end with a mounting 23 to support and secure the power source 21, which may be pneumatically or electrically driven.

The shearing machine also comprises two support wheels 24,

25 journalled on a shaft 26 secured to the lower part of the body. The shearing machine on wheels is thus readily mobile and can be easily manoeuvred by the operator to a convenient working position during the shearing opera- tio .

The drive source is preferably of stepless type so that the sheet can be sheared at a controlled speed depending on the conditions prevailing. The sheet feed through the nip thus depends on the speed of the driven shearing wheel - 5. Provided a drill with reverse gear is used, the shearing machine can be reversed into a cut already made. This is extremely useful when cutting pieces from a large sheet.

A conical support 27 is arranged in connection with the lower shearing wheel 6. This supports the piece of sheet which passes beneath the deflector during the shearing process. The conical surface deviates from cylindrical form by an angle σC , and the sheet will therefore be supported on a surface disposed in the plane of the sheet during the shearing process.

The shearing machine may also be constructed for shearing on a bench or the like, i.e. at normal arm level, in which case the drive shaft 20 and the bar 22 can be shortened or removed entirely from the above .described embodiment and mounting for the power source is combined directly with the body to enable detachable connection of the power source to the reduction gear shaft.

As is clear from the drawings and the description above, the shearing machine is impeded by no elements whatsoever at the sides on a level with the nip 20 of the shearing wheels 5, 6 or near the deflector. There is thus nothing to obstruct the relative movement of the sheet or the shearing machine. This means that the sheet to be cut may

have any desired width and the cut can be made to an arc, even an arc with very small radius. Neither is there any obstruction at said level in the direction of relative movement of the sheet after the cut has been made, i.e. 5 behind the shearing machine.

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Thus the shearing machine according to the present inven¬ tion surprisingly enables heavy-gauge sheet of any material to be cut. Sheet of virtually any desired gauge can be cut by appropriate dimensioning of the shearing wheels and power 10 source. The edges of the cut are clean and uniform, re¬ quiring no subsequent machining, unlike the edges obtained in flame cutting, which additionally destroys the hot hardening of the sheets.

The actual shearing operation is virtually silent and 15 smooth, with excellent control of the shearing line at the speed considered appropriate, particularly if a variable speed transmission is used.

Large sheets can be cut and there is no difficulty in cutting long, even curves after the sheet has been placed 20 on the supports at the nip level. An important advantage is also that a conventional drill can be used as power source and can be rapidly and easily connected to the shearing machine as shown and described above.