Mining or in situ disintegration of hard material – Cutter tooth or tooth head – Planar type bit mount
Reexamination Certificate
1999-01-26
2001-02-13
Bagnell, David (Department: 3673)
Mining or in situ disintegration of hard material
Cutter tooth or tooth head
Planar type bit mount
C299S102000
Reexamination Certificate
active
06186597
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a pick system for mining ploughs, in particular coal ploughs, of the kind comprising at least one pick holder arranged on the plough head or on a pick carrier thereon, and a replaceable plough pick insertable by its shank into a matching socket in the pick holder in which it is held, with rear end support and with an interference fit, in its working position with its cutting tip projecting from the socket on the working side and in which it is secured against detachment by a securing element which can be displaced from a locking position when the pick is to be replaced.
BACKGROUND OF THE INVENTION
Coal ploughs used successfully for many years in underground long wall face workings have pick holders arranged on the plough heads, usually on pick carriers pivotally mounted thereon, and provided with sockets into which the plough picks can be inserted by their shank, which is usually flat-sided. The shanks of plough picks which are known and in common use are matched in its conformation and dimensions to the shape and size of the sockets in which they are inserted, so that the picks are held in the sockets of the pick holders with their shanks in form-fitting engagement. To stop the picks from coming out of their holders in the opposite direction to their insertion direction when the plough is in operation, when the plough performs its working motion in the opposite direction to its cutting direction, it is necessary to provide some means of securing the picks in their sockets. Numerous such means have been proposed, e.g. locking pins, studs, and bolts; retaining keys; collets secured with heavy duty dowel pins or screws, etc. (DE-PS 1291708, DE 2538682 C2, DE 3440448 C2, DE 3531781 C1, DE 3122868 C2, DE 3806363 C2, DE 4105238 C2, DE 4431701 C2).
In the known plough pick systems commonly used in mining for many years, the pick holders are invariably designed so that the picks have to be inserted by their shanks into the sockets from the working or coal face side, and must be removed from the sockets in the pick holders towards that side, after the securing elements have been released, when pick replacement is necessary. Frequently the clearance needed for this operation between the plough, or its picks, and the coal face is available only at the end of a long wall face.
The known plough pick systems commonly used in the mining industry usually require, besides the securing elements used as loose parts, additional fastening elements for fixing the securing elements in the locked position. Such fastening elements include, among others, elastic clamps, plastic plugs provided with steel pins, clamping collets and screws, etc. The result of using such additional fastening elements is that production costs, and consequently plant costs, are increased. In many cases the known systems are difficult to handle when picks are being inserted or replaced, and/or are unreliable in service so that losses of picks while the plough is operating are not uncommon. One known system uses securing elements consisting of captive spring-mounted plunger pins on the pick which automatically snap into the locked position upon insertion of the pick into the holder (DE 4102140 A1). Here again the picks must be inserted into the pick holders from the working side, and removed towards that side.
Taking as its starting-point a plough pick system of the kind initially referred to, the invention has the basic object of providing a pick arrangement, suitable for use in mining, which can be handled more easily when the pick is inserted into the holder, and also when the pick is being removed for replacement.
SUMMARY OF THE INVENTION
In accordance with the invention, the pick holder has, on the side leading in the working direction of the pick, a pick lead-through opening through which the pick is insertable by the shank as far as a rear stop in the pick holder socket and through which the pick is removable, after the securing element has been unlocked, when it is to be replaced.
With the pick system configuration according to the invention, the pick can be inserted into the socket in the pick -holder not from the working side as in the past, but from the side which is at the front in the direction of cutting, through the pick lead-through opening provided on that side, and removed in the opposite direction via the said lead-through opening when replacement is necessary. The job of inserting the picks into the pick holders, and also that of replacing the picks, is made much easier, as increased clearance between the picks and the working face is not required; instead, the clearance usually present in front of the pick holders can be utilized. Production can also be simplified in a number of ways with the configuration of pick holders according to the invention, with the form-fitting seating and support of the picks in their sockets. Matters can be advantageously arranged so that the front lead-through opening in the pick holder is extended to form an opening in the pick holder on the working side from which the pick's cutting tip can project.
In accordance with another important feature of the invention, the interior of the socket in the pick holder has at least one shank bearing and guiding surface which is inclined at an oblique angle to a plane parallel with the cutting direction, so that when the pick is removed from the lead-through opening its outlying cutting tip is moved away from the working face. With this embodiment of the pick system, when the pick is removed for replacement it is guided forwards by the pick holder in a constrained manner, causing its outlying tip to move away from the working or mining face, so that the pick can be replaced easily and quickly even if its cutting tip is in close proximity to the working face. Conversely, this feature also facilitates insertion of the pick into the socket. It is advisable that the said bearing and guiding surface in the socket, and the side face of the pick shank which is guided by this surface on insertion and removal of the pick, be set at an oblique angle of some 5° to 20°, preferably 5° to 10°, to a plane parallel with the cutting direction.
As is customary in known plough picks, which, like those according to the invention, are, as a general rule, designed for one-sided cutting, the pick provided in the system according to the invention is held by its shank in the pick holder socket in a form-fitting manner, and is supported at the rear by the pick holder against the cutting forces occurring in operation. In another advantageous configuration of the invention, the pick shank has a rear supporting and guiding extension engaging in a recess in the pick holder socket in which the shank is held in a form-fitting manner, and the axis of the recess in the socket and that of the supporting and guiding extension engaging therein are inclined at the abovementioned oblique angle. The tenon-like supporting and guiding extension fixedly and integrally arranged on the shank of the pick according to the invention positively locks the pick in the pick holder in the transverse direction, and also serves to guide the pick on its insertion or replacement. The supporting and guiding extension may be given some other cross-section, for example a round cross-section, or alternatively a flattened segmental cross-section. In each case, the said socket recess is adapted to the cross-section of the supporting and guiding extension.
A particularly advantageous embodiment of the invention is obtained if the pick shank and/or the supporting and guiding extension has a conical taper, or when viewed in plan narrows trapezoidally, from its front region towards its rear end. In this self-centring embodiment the side surfaces of the pick shank and/or of its supporting and guiding extension do not make full-face contact with the surrounding surfaces until the end of the insertion movement, which greatly facilitates insertion of the pick.
Rear-end support of the pick inside the pick holder may be provided through-the said supporting
Hahn Detlef
Heiderich Ernst
Marker Georg
Richter Peter
Wald Wolfgang
Bagnell David
DBT Deutsche Bergbau--Technik GmbH
Singh Sunil
Vickers Daniels & Young
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