GB2073642A - Blade retainer for billet shears - Google Patents

Abstract

A blade-retaining means for billet shears comprising a blade holder (1) with a V-shaped recess (2) therein in which a two part blade (5, 6) is clampable on bearing members (3, 4). Each bearing member has a bearing surface with lamina-like resilient tongues (13) which extend at an inclination to the bearing surface; each bearing member (3, 4) has for receiving a blade half (5, 6) a recess, which is formed by a strip (7) on the narrow, outer side of a blade half and also by a strip (8) on one longitudinal side of said blade half. Each blade half (5, 6) when inserted into the recess of a bearing member (3, 4) projects beyond the inner narrow side of the associated bearing member (3, 4), to leave a distance a therebetween in the zone of the centre line of the billet to be cut. <IMAGE>

Description

SPECIFICATION Blade-retaining means for billet shears This invention relates to blade-retaining means for billet shears, and more particularly to shears in which two cemented-carbide blade halves may be clamped by chucking wedges into a blade holder in a blade support.

German Auslegeschrift 1 160 274 discloses blade-retaining means for billet-shears, in which a blade divided in line with the profile centre and adapted to the billet cross section is clamped by chucking wedges in the blade holder. The blade holder fitted into the blade supports is rectangular in construction so a large amount of material is needed which makes it very expensive.

German Democratic Republic Patent Specification 120 175 discloses a billet shears blade-retaining means which is improved with regard to the amount of material used whereby blade-retaining means located in the receiving recess in the blade support is in the shape of a V.

The blade, also divided in line with the profile centre of the shearing cross section, is formed by two strip-like blade halves which are inserted into the V-shaped receiving recess and clamped tightly by two oppositely acting chucking wedges in combination with additional tightening screws disposed in each blade half. In this prior art bladeretaining means, spacing shims are inserted between the blade halves and the support of the top blades to adapt the blades to the profile size of the billets, in accordance with the height of stroke of the billet shears.

Owing to their constructional features, the known blade-retaining means for billet shears are suitable only for blades-made of tool steel. Due to the intermittent loadings on the cutting edges during the shearing of round, square or flat steel billets, the blades must not only be as hard as possible but they must also be very tough to prevent jagging of the cutting edges. As a result; there are pre-determined limit values for the material which can be used for the cutting edges, and this means that full use cannot be made of high-alloy hot or cold worked steels.For this reason it has also hitherto proved impossible to make use in billet shears of shearing blades which are made of cemented-carbide, although due to its considerable hardness, which is preserved even at elevated working temperatures, the lastmentioned material seems to be particularly suitable to be used in billet shears.

It is an object of the invention to provide a btade-retaining means for billet shears which enables cemented-carbide shearing blades to be used and prevents jagging of the cutting edges as a result of the heavy intermittent loading of the cutting parts thereby ensuring economic use of the cutting material and also a long life of the blades themselves.

The problem to which the invention relates is to improve the blade holders of known bladeretaining means for billet shears with divided blades so as to absorb the intermittent loading exerted on the cutting parts during the shearing operation.

To this end, the present invention provides an arrangement in which bearing members are disposed, in use, between each blade half of the divided blade and the V-shaped recess of the blade holder; the bearing surface of each bearing member has lamina-like resilient tongues which extend at an inclination thereto; each bearing member has for receiving a blade half a recess, which is formed by a strip disposed on the narrow, outer side of its blade half and also by a strip disposed on one longitudinal side of said blade half, and each blade half is insertable into the recess of a bearing member to project beyond the inner narrow side thereof so that a-distance is left between the bearing members in the zone of the profile centre.

Preferably, the clamping of the blade halves inserted in the bearing members is performed by two oppositely acting chucking wedges which engage with the strips on the narrow, outer side of the bearing members via clamping surfaces which also have lamina-like resilient tongues.

An important feature of the invention is the function and construction of the bearing members.

Due to their resilient properties, the resilient tongues disposed on the bearing surface of the bearing members produce a springing of the blade halves during the intermittent impact of the top blade on the billet to be shorn off, and thereby damp loading on the cutting edges. In these conditions, the shearing operation takes place resiliently, thus enabling even materials of great hardness, more particularly cemented-carbide, to be used for making the blade and blade halves, without the risk of jagging the cutting edges. The resilience of the blade holder also demands a clamping arrangement which preferably has a correspondingly resilient intermediate member.

This function can be performed by the resilient tongues which may be provided on the clamping surface of the chucking wedges. The resilience of the bearing members is also ensured by the feature that they are shorter than the blade halves mountable thereon and are at a distance from one another in the zone of the place of contact and separation of the blade halves - i.e., in the zone of the profile centre. In addition to the resilient reduction of the intermittent loading, the bladeretaining means also evens out expansion differences between the individual structural components such as occur during the shearing of pre-heated billets by the heating up, more particularly of the blade halves, resulting therefrom.In this respect the chucking wedges having resilient tongues act in conjunction with the resilient tongues of the bearing members and prevent the release of the clamping forces retaining the blade halves in their position.

A preferred embodiment of the invention will now be described in greater detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a sectional side elevation of blade retaining means for billet shears for the shearing of steel billets of circular cross section; Figure 2 is a plan view of Figure 1; and Figure 3 is a further side elevation of a part of Figure 1 but sectioned along the line A-A in Figure 2.

Referring to the drawings, there is shown a blade-retaining-means for billet shears comprising a blade holder 1 formed with V-shaped recess 2 therein into which two bearing members 3 and 4 are inserted together with cemented-carbide blade halves 5 and 6. For receiving its blade half, each bearing member 3, 4 defines a recess which is formed between a strip 7 positioning along the narrow, outer side of a blade half 5, 6 and a strip 8 positioned along one longitudinal side of the blade half 5, 6. The resulting recess in the bearing members 3 and 4 determines the position of the blade halves 5 and 6, which extend upwardly from the bearing members 3 and 4 on the inner narrow side, so that a gap a is produced between the bearing members 3 and 4 below the place of contact of the two blade halves 5 and 6 - i.e., on the centre line 9 of the billet 10 to be shorn off.

The cutting edges 1 1 and 12 of the inserted blade halves 5 and 6 produce the semi-circular contour of the circular billet 10 which is to be shorn off.

Also adapted to the shape of the cutting edge parts 1 1 and 12 are the strips 8 on the longitudinal sides of the bearing members 3 and 4, their shape being set back in relation to the cutting edges 1 1 and 12, in accordance with the amount of regrinding needed.

On their bottom sides which bear against the Vshaped recess 2 of the blade holder 1, the bearing members 3 and 4 have lamina-like resilient tongues 13 which extend at an angle to the bearing side, these tongues 13 absorbing the intermittent loading of the cutting edges 11 and 12.

The blade halves 5 and 6 are attached and clamped by chucking wedges 14 which engage with the strip 7 on the narrow outer side of the bearing members 3 and 4 and are clamped by tightening screws 15. The clamping surfaces of the chucking wedges 14 also have resilient tongues 16, which provide the required resilience to the clamping arrangement.

Claims (3)

1. A blade retaining means for billet shears comprising a blade holder having a V-shaped recess therein in which a blade divided into two parts in line with the centre line of the billet to be cut is clampable by clamping means on bearing members, each bearing member having a bearing surface with lamina-like resilient tongues thereon which extend at an inclination thereto, and each bearing member having a recess for receiving one of said blade halves, said recess being formed by a strip disposed, in use, on the narrow, outer side of the blade inserted therein and a strip disposed along one longitudinal side of said blade half, each blade half being insertable into said recess to project beyong the inner narrow side of its associated bearing member to leave a gap between the bearing members in the area of the centre line of the billet to be cut.

2. A knife-retaining meansfof billet shears as claimed in claim 1, wherein chucking wedges engage with the strips provided on the narrow, outer side of the bearing members, the clamping surfaces of the chucking wedges clamping surfaces with lamina-like resilient tongues thereon.

3. A knife-retaining means for billet shears substantially as herein described with reference to the accompanying drawings.