GB2105388A - A mineral cutting tool, particularly a ploughing or shearing tool - Google Patents

Abstract

A mineral cutting tool comprises a pick 1, a pick holder 2 and a releasably latching device 3 for the pick 1, a shank 4 of the pick 1 being insertable into a recess of the pick holder 2. In order to obtain shock- absorbed operation of the pick 1, the shank 4 has a grooved recess 10 open at the free end of the shank 4 and extending inwardly therefrom, with a separation plane 11 extending transversely to the direction of working and thereby defining a forward spring limb 12 and a rearward fastening limb 13 of the shank 4. <IMAGE>

Description

SPECIFICATION A mineral cutting tool, particularly a ploughing or shearing tool The invention relates to a mineral cutting tool, particularly to a ploughing or shearing tool, with a pick, a pick holder and a detachable fastening device for the pick, the pick being insertable by means of a shank into a recess of the pick holder, and the shank having a detent recess with a holding surface into which a clamping stud of the pick holder engages.

It is well known that, in use, ploughing and shearing tools are subjected to considerable shock and impact loadings. This frequently leads to premature damage or even to loss of the hard metal tips with which the cutting faces of the tools are armoured. The invention is intended to offer help in this respect.

The object of the present invention is to provide a mineral cutting tool, particularly a ploughing or shearing tool of the above-described type in which the tool works under shock-absorbing conditions in the tool holder.

According to the present invention there is provided a mineral cutting tool, particularly a ploughing or shearing tool, comprising a pick, a pick holder and a detachable fastening device for the pick, a shank of the pick being insertable into a recess of the pick holder, the shank having a detent recess with a holding surface into which a clamping stud of the pick holder is engageable, the shank having a grooved recess open at the free end of the shank and extending inwardly therefrom, with a separation plane extending transversely to the direction of working, and thereby defining a forward spring limb and a rearward fastening limb of the shank.

The invention is founded on the recognition that when the pick is in use, a torque occurs by which the shank, particularly in the region of its base, is pressed against the corresponding contact surface of the pick holder recess, especially as support of the pick in its upper area of transition from its head portion to its shank occurs at its rear shank surface against the pick holder recess which there widens out and forms a buttress.On account of the division of the shank that is taught in accordance with the invention, by virtue of the grooved recess which extends transversely to the direction of working, a forward and a rearward limb are formed, whereby with appropriate design of shape of cross-section, the forward limb fulfils the function of a spring limb in relation to the pressure forces there occurring, whilst the rearward limb, considerably relieved of load, can fulfil the function of a fastening limb which is performed by the detent recess for the spring loaded clamping stud of the detachable fastening device.The spring limb makes possible a shock absorbing withdrawal movement of the pick during shock and impact loading around an axis of swing transverse to the operating direction, towards the rear of the pick in the transitional area between the shank and the head portion, on account of the buttress-like support in the pick holder recess or against the pick holder. It is an important feature of the invention that the shank itself does not have to be - as with normal constructions -- of solid material, but on account of the existence of the grooved recess according to the invention, is capable of absorbing perfectly the loads occurring on the pick, in use, and in addition to this enables shock-absorbing operation of the pick so that premature damage and even loss of the hard metal tips forming the cutting faces is no longer to be feared.The principal advantages achieved by the invention are to be seen in this.

Further preferred features of the invention are described as follows. The invention recommends that the grooved recess is formed as an inverted V-shaped recess on the uniform-rigidity beam principle. In this way the shock-absorption effect is further improved because the spring action of the spring limb is particularly effective. This applies still more in view of the fact that in accordance with a further feature of the invention, the grooved recess possesses, at least on the spring limb side, a concave inner surface. Thus the spring limb is constructed with spring elasticity just at the point where its foot presses against the corresponding contact surface of the pick holder recess, and it possesses a strengthened crosssection in the pick head portion.The invention further teaches that a clamping groove with constrictions in the transition region is located at the apex of the V of the grooved recess, to clamp the connecting bar of a double stud of flexible elastic material such as rubber or plastics. The flexible elastic double stud serves to dampen transverse movements of the pick in the pick holder. In fact movement play between the shank and the pick holder recess, and hence between the pick and the pick holder recess, are as a rule unavoidable for manufacturing reasons. The transverse movements of the pick or its shank in the pick holder resulting from this are absorbed by means of the double stud according to this feature of the invention, which in addition to this prevents, or at least greatly reduces, vibration effects that occur with the rigid connections hitherto used.

Finally the clamping groove at the apex of the V of the grooved recess prevents any harmful notch effects.

The invention will now be described in greater detail, by way of examples, with reference to the accompanying drawings, in which: Figure 1 is a side elevation, partly in section, of a mineral cutting tool in accordance with the invention, with an enlargement of the clamping stud portion; Figure 2 is a plan view of Figure 1; and Figure 3 is a sectional view, to an enlarged scale, of the clamping groove portion of Figures 1 and 2.

In the drawings is shown a mineral cutting tool comprising a shearer pick 1, a pick holder 2 and a releasable latching device 3 for releasably fastening the pick 1 to the pick holder 2. As is known, such a pick is used with rotary cutting heads -- known as spiral vane shearer drums or discs - or with shearing chains or the like. The direction of shearing is indicated by the arrow of Figure 1 pointing to the right. The pick 1 is inserted by its shank 4 into a recess 5 of the pick holder 2. The shank 4 possesses a detent recess 6 with a slanting holding surface 7 into which a clamping stud 8, which is supported in the pick holder 2, engages and there fits against the slanting holding surface 7.This clamping stud 8 can be retracted against the effort of a return spring 9 in the well-known manner by a lever (not shown) or the like, whereby the latching device 3 is retracted from the position illustrated in which it projects into the recess 5, and a pick 1 can be replaced. The shank 4 has a grooved recess 10, open at the free end of the shank and extending inwardly therefrom, with a separation plane 11 extending transversely to the direction of working.

Thereby the shank 4 is subdivided into a forward spring limb 12 and a rearward fastening limb 13.

The main forces exerted on the pick 1 when working are indicated by the other arrows of Figure 1, which clearly show that a torque arises which ensures that the pick 1, supported from the rear, is pressed with its spring limb 12 and particularly the bottom portion of this spring limb against the corresponding contact surface 14 of the recess 5 and thereby provides a shockdampening effect. Consequently the shock and impact loadings acting on hard metal tips 15, with which the cutting surfaces of shearing pick 1 are faced, are considerably reduced, and in any case are smoothly absorbed. A grooved recess 10 is formed as an inverted V-shaped recess and has a concave inner surface, at least on the spring limb side. Thereby the spring effect of spring limb 12 is further increased. Also a clamping groove 1 6, with constrictions in the transition region, Is located at the apex of the V grooved recess 10, to clamp a connecting bar 17 of a double stud 18 of flexible elastic material, such as rubber or plastics, so that pick 1 also receives transverse support and Its transverse movements arising from the normal play are likewise damped. Of course the spring limbs 12 and 1 3 act pre-eminently in an elastic and shock-absorbtng manner in this case also, because the play space becomes filled with debris/dust etc. when the mineral cutting tool is operating. At the same time pick 1 is held In a practicable manner so that quick and easy replacement is ensured,

Claims (4)

1. A mineral cutting tool, particularly a ploughing or shearing tool, comprising a pick a pick holder and a detachable fastening device for the pick, a shank of the pick being Insertable into a recess of the pick holder, the shank having a detent recess with a holding surface into which a clamping stud of the pick holder is engageable, the shank having a grooved recess open at the free end of the shank and extending inwardly therefrom, with a separation plane extending transversely to the direction of working, and thereby defining a forward spring limb and a rearward fastening limb of the shank.

2. A cutting tool as claimed in Claim wherein the grooved recess is formed as an inverted V-shaped recess.

3. A cutting tool as claimed in Claim 1 or Claim 2, wherein the grooved recess has, at least on the spring limb side, a concave inner surface.

4. A cutting tool as claimed in Claim 2 or Claim 3 when appendant to Claim 2, wherein a clamping groove with constrictions in the transition region Is located at the apex of the V of the grooved recess, to clamp a connecting bar of a double stud of flexible elastic material.