EP0521413B1 - Fixing of a shearing pick in its holder - Google Patents

Abstract

During the fixing of a shearing pick (16) in its holder, the shearing pick (16) having a pick shank (15) and the holder having a pick pocket (8) which accommodates the pick shank (15) and is fixed to the work head (2) of a winning machine, with at least one holding element which holds the shearing pick (16) in the pick pocket (8), each holding element being designed as at least one working piston (13) which is arranged in the pick pocket (8), can be actuated by pressure and exerts on the shearing pick (16) a clamping force directed perpendicularly to its longitudinal axis (16c), short replacement times are made possible in a simple shape of the shearing pick (16) without a great deal of design effort and at the same time the reliable retention of the shearing pick (16) in the holder for the entire duration of its use is ensured by each working piston (13) being acted upon by pressure via a pressurised supply line (3) for spray liquid supplying at least one spray nozzle. <IMAGE>

Description

The invention relates to an attachment of a cutter bit in its holder, the cutter bit having a cutter shaft and the holder having a cutter pocket which receives the cutter shaft and is fastened to the working head of a mining machine, with at least one holding element by which the cutter bit is held in the cutter pocket, wherein each holding element is designed as at least one pressure-actuated working piston arranged in the chisel pocket, which exerts a clamping force directed perpendicularly to the longitudinal axis of the chiseling chisel.

Large quantities of dust fall during the underground extraction of mineral resources, for example coal, with cutting machines which endanger the health of the miners operating the machines. Therefore, during the operation of these extraction machines, water is injected under high pressure into the working area of the cutter bit, so that the dust is bound by the liquid vapor thus formed. In order to effectively prevent the formation of dust, the outlet nozzle for the spray liquid is arranged as close as possible to the location of the dust formation, specifically the chisel tip of the cutting bit itself or its holder.

During their use, the cutting chisels are loaded by large forces acting perpendicular to their longitudinal axis and, depending on the composition of the processed rock, are subjected to severe wear. They must therefore be replaced after a certain period of use. The extraction machine must be shut down to replace the chisels. Since mining operations are interrupted during this time, the bit changes lead to an increase in operating costs.

There are many known ways of reducing the time required for replacing the cutter bit by designing and handling the attachment of the cutter bit in the holder as simply as possible. For example, a cutting chisel of the type mentioned at the outset is known, the chisel shaft of which has depressions into which clamping elements made of elastic material projecting beyond the side walls of the chisel shaft are inserted.

In this way, a frictional engagement is formed between the inner walls of the chisel pocket and the chisel shaft after inserting this chisel chisel into the chisel pocket of the holder.

The advantage of this attachment lies in the fact that, in contrast to the further known prior art, no additional attachment elements, such as clamping wedges or locking pins, are required for fixing the cutting bit in the chisel pocket of the holder. It proves to be disadvantageous, however, that the clamping forces of the clamping elements have to be overcome both when inserting and when pulling out the cutting bit. In addition, premature wear of the elastic clamping elements can occur with these cutting bits, as a result of which the safety of the attachment of the bit in the holder is impaired.

From DE-A-39 35 691 a chisel arrangement for mining extraction machines is known, the chisel being insertable in the chisel pocket of a chisel holder and being fixed in the chisel pocket by means of a securing element. In this case, the securing element can be raised into the locking position by hydraulic pressurization of an actuating cylinder space and / or can be reset from the locking position into the unlocked position. At least one displacement piston is used for pressurizing the actuating cylinder space and, depending on whether a chisel or several chisels are to be locked together, can be arranged on the chisel pocket or on a tool carrier carrying the chisel pocket. In any case, a system that is closed to the outside and filled with hydraulic medium, within which the hydraulic medium is displaced with the aid of the displacement piston, is used. The known chisel arrangement is technically complex since at least one independent hydraulic system must be created. If a common displacement piston is used, a plurality of chisels can thus be locked or unlocked at once, but this leads to a relatively large displacement piston unit. If separate displacement pistons are used for each chisel holder, they can be made small and arranged in the vicinity of the chisel, but a separate work step is required to lock and unlock each individual chisel.

The invention is therefore based on the object of creating a fastening of a cutter bit without great design effort, which allows short replacement times with a simple shape of the cutter bit and at the same time ensures the secure hold of the cutter bit in the holder for the entire duration of its use.

This object is achieved in the generic attachment of a cutter bit in a holder according to claim 1 in that each piston is pressurized via a pressurized supply line for at least one spray nozzle supplying spray liquid.

By means of the invention, the spray liquid under pressure in the liquid supply line is used as a hydraulic force transmission medium, in that the liquid pressure is converted into a clamping force acting on the chisel shaft with the aid of at least one working piston. Since the extraction machine is only put into operation when there is sufficient fluid pressure, this is the case for the entire operating time of the cutter bit Clamping of the chisel ensured in the chisel pocket of the holder.

If the extraction machine is stopped to change the worn chisel, the spray liquid flow is also interrupted at the same time, so that the pressure in the feed line drops. At the same time, the working piston is free of force and the chisel bit of the cutting bit is relieved of the clamping force. The chisel chisel can then be removed from the holder with a simple movement without effort.

The chisel bit of the cutter bit can have an easy-to-produce shape since no additional fastening elements have to be attached to it. In addition, the requirements for the dimensional accuracy of the chisel shaft can be reduced because the positive locking between the walls of the chisel shaft and the walls of the chisel pocket of the holder is ensured at all times by the clamping exerted by the working piston.

If the cutter bit is particularly unevenly subjected to large forces acting on it, the retention of the extraction bit in the holder can be improved in that the bit pocket has two working pistons which are arranged in opposite side walls of the bit pocket and are axially offset in the axial direction of the bit shaft. Due to the offset working pistons, the cutting chisel is tilted in the chisel pocket during the action of the clamping forces. The offset of the working pistons can be selected so that the cutter bit is additionally supported at the points of contact of the chisel shaft and the chisel pocket against the cutting forces stressing it.

Any movement of the cutting chisel in the direction of its longitudinal axis can be avoided in that the chisel shaft has a depression in which the working piston engages. A particularly secure mounting can be achieved in that the depressions have a longer, inclined base surface as a working surface for the working piston in such a way that the cutting bit is drawn into the chisel pocket when the working piston is pressurized. In this way it can also be ensured that the head of the cutting bit is supported on the upper side of the holder by means of projections formed in the transition area between the bit head and the bit shaft.

The power transmission between the working piston and the chisel shaft can be further improved in that the working piston has a curved end face. Because of this shape of the piston there is point contact between the chisel shaft and the working piston. This facilitates the movement of the cutting chisel during clamping and ensures that the chisel shaft comes to rest on the surfaces of the chisel pocket provided for this purpose.

If the safety of the cutter bit holder in the holder is to be increased further, this can be done in that the bit shaft and the bit pocket have a uniform prismatic cross-section and the bit shaft can be pushed into the bit pocket with play and that at least one working piston is located opposite one of the edges is arranged, which are formed between two acute-angled side surfaces of the chisel pocket.

Fig. 1

eine Halterung mit eingesetztem Schrämmeißel im Längsschnitt;

Fig. 2

die Halterung gemäß Figur 1 in Aufsicht;

Fig. 3

ein Halteelement der Halterung gemäß Figur 1 in vergrößerter Darstellung als Ausschnitt X der Figur 1;

Fig. 4

die Halterung gemäß Figur 1 im Schnitt entlang der Schnittlinie I-I der Figur 1.

The invention is explained in more detail below with reference to a drawing which represents an exemplary embodiment. Show it:

Fig. 1

a holder with inserted cutting chisel in longitudinal section;

Fig. 2

the holder of Figure 1 in supervision;

Fig. 3

a holding element of the bracket according to Figure 1 in an enlarged view as section X of Figure 1;

Fig. 4

1 in section along the section line II of FIG. 1.

A holder 1 with a chisel pocket 8 is welded to a working head 2 of a cutting machine. A groove-shaped feed channel 3 is formed on its outer rear side 1a and is connected to a pressure line 2a for spray liquid formed in the working head 2. From the feed channel 3 lead in the upper 1b and the lower wall 1c perpendicular to the rear 1a bores 4,5 each to an upper threaded opening 6 arranged in the area of the end face 1d of the holder 1 and a lower, opposite the upper in the direction of the rear 1a of the holder 1 offset threaded opening 7. The threaded openings 6, 7 extend from the outside of the walls 1c, 1d to the mouths of the bores 4, 5 and are smaller in diameter through bores 6a, 7a the chisel pocket 8 formed by the walls of the holder 1 is extended.

The chisel pocket 8 has a hexagonal, prismatic cross section, the edges 8c, 8d of which are formed between the surfaces 8a, 8b which meet at an acute angle, are arranged in the upper and lower walls 1b, 1c of the holder.

Pressure cylinders 9, 10, which are provided with a threaded section 10a and a hexagonal screw head 10b, are screwed into the threaded openings 6, and are extended below the threaded section 10a by a cylindrical wall 10c. A circumferential groove 10d, in which an O-ring 11 is seated, is formed in the cylindrical wall 10c at a distance from the threaded section 10a. The O-ring 11 seals the circumferential liquid channel 12 formed between the threaded section 10a and the groove 10d with respect to the chisel pocket 8. The threaded section 10a is divided by two opposing second grooves 10e arranged perpendicular to the circumferential groove 10d, each of which is connected via a bore 10f arranged below the screw head 10b to a cylinder space 10g enclosed by the threaded section 10c and the extension of the grooves 10e. A working piston 13, which leaves the opening of the bore 10f open, is inserted into the cylinder space 10g with little play. The cylinder space 10g is also sealed off from the chisel pocket 8 by an O-ring 14 which is inserted in an open groove 13a which runs around the circumference of the working piston 13. The end face 13b of the working piston 13 is curved as a spherical section.

A chisel shaft 15 of a cutting chisel 16, which is similar in shape to the cross section of the jacket pocket 8 Cross section has been inserted into the chisel pocket 8 with play. On the upper and lower edges 15a, 15b of the chisel shaft 15, notches 15d are arranged opposite to the working pistons 6,7 and extend transversely to the longitudinal axis 15c of the chisel shaft 15 and have a long base surface 15e inclined towards the tip 16a of the cutting bit 16. The cutting chisel 16 has, in the region of the transition to the chisel shaft 15, projections 16b which abut against the end face 1d of the holder 1 as stops.

When the cutting machine is started up, pressurized spray liquid is fed into the feed channel 3 via the pressure lines 2a and from there passes through the bores 4, 5, the circumferential fluid channel 12, the vertical grooves 10e and the bores 10f into the cylinder space 10g of the working cylinder 10 When the cylinder space 10g is pressurized, the drive piston 13 is pressed out of the cylinder space 10g until its curved end face 13b meets the respectively inclined base surface 15e of the notches 15d. The curved end face 13b of the working piston 13 reliably prevents the cutting bit 16 from accidentally falling out even when the pressurization is no longer present. From this point on, a clamping force directed perpendicular to the longitudinal axis 16c of the cutter bit 16 is exerted via the working piston 13, the force direction of which is redirected on the inclined base surfaces 15e in such a way that the clamping force has a force component directed towards the rear side 1a of the holder 1. This component of force pulls the cutting chisel 16 into the chisel pocket 8 of the holder 1 until the projections 16b Form-fit against the end face 1d of the holder 1. Due to the staggered arrangement of the two working pistons 13, the chisel bit 16 simultaneously executes a slight tilting movement and is tilted in the chisel pocket 8 by the remaining force component of the clamping force directed perpendicular to the longitudinal axis 16c of the chisel bit 16.

To change the worn cutting chisel 16, the cutting machine is stopped and the spray liquid flow is interrupted, as a result of which the pressure in the cylinder space 10g drops and the working piston 13 becomes force-free. The cutting chisel 16 can now be pulled out of the jacket pocket 8 without effort.

During the extraction, the working pistons 13 are pushed back into the cylinder space 10g by their curved end faces 13b sliding on the inclined base surface 15e of the recess 15d. In this way, the chisel shaft of the new cutting chisel can be pushed into the chisel pocket 8 unhindered.

Claims (7)

1. An attachment of a shearing pick (16) in its holder, the shearing pick (16) having a pick shank (15), and the holder having a pocket (8) which receives the pick shank (15) and is attached to the working head (2) of an extracting machine, at least one retaining element being provided by which the shearing pick (16) is retained in the pocket (8), each retaining element taking the form of at least one pressure-actuatable working piston (13) which is disposed in the pocket (8) and which exerts on the shearing pick (16) a clamping force directed perpendicularly to its longitudinal axis (16c), characterized in that each working piston (13) is pressure-actuated via pressurized supply line (3) for spraying the fluid supplied to at least one spray nozzle.
2. An attachment according to claim 1, characterized in that the working piston (13) is disposed in a working cylinder (10) which can be pressure-actuated by the spraying fluid and which is screwed into a tapped opening (6, 7) with which one side wall (1b, c) of the pocket (8) is formed.
3. An attachment according to claims 1 or 2, characterized in that the pocket (8) has two working pistons (13) which are disposed in opposite side walls (1b, c) of the pocket (8) and are offset axially in the axial direction of the pick shank (15).
4. An attachment according to one of claims 1 to 3, characterized in that the pick shank (15) is formed with a depression (15d) in which the working piston (13) engages.
5. An attachment according to claim 4, characterized in that the depressions (15d) have an inclined base surface (15c) which acts as an engagement surface for the working piston (13) and is so inclined that when the working piston (13) is pressure-actuated, the shearing pick (16) is drawn into the pocket (8).
6. An attachment according to one of the preceding claims, characterized in that the working piston (13) has an arcuate end face (13b).
7. An attachment according to one of the preceding claims, characterized in that the pick shank (15) and the pocket (8) have a uniform prismatic cross-section and the pick shank (15) can be inserted with clearance into the pocket (8), and at least one working piston (13) was disposed opposite one of the edges which are formed between two lateral surfaces (8a) of the pocket (8) which are disposed at an acute angle.

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