GB2128525A

GB2128525A - Sleeve retainer

Info

Publication number: GB2128525A
Application number: GB08320661A
Authority: GB
Inventors: Jarma Leppanen
Original assignee: Tampella Oy AB
Current assignee: Tampella Oy AB
Priority date: 1982-08-27
Filing date: 1983-08-01
Publication date: 1984-05-02
Also published as: SE8304619L; FI822981A0; FI65470C; GB2128525B; SE8304619D0; FI65470B; DE3330611A1; FR2532357A1; GB8320661D0

Abstract

A sleeve retainer for use in an extension rod drilling machine when uncoupling a drill rod from the drill motor drive shaft comprises a frame (8) mountable on the feeding beam (2) of the machine, two jaw arms (12, 13) mounted coaxially and pivotably on the frame (8) and provided with jaws (14) facing each other, and a pressure-fluid operated actuating means (15) which pivots the jaw arms (12, 13) to a gripping position, in which the jaws (14) would be pressed against the connection sleeve (6) of the drill rod, and to an open position, in which the jaws (14) are displaced away from each other (Fig. 4). The actuating means is connected to the jaw arms (12, 13) so that the jaw arms (12, 13) and the actuating means (15) form a unit which is freely pivotable around the pivot shaft (11) of the jaw arms (12, 13) with respect to the frame (8). <IMAGE>

Description

SPECIFICATION Sleeve retainer for an extension rod drilling apparatus The present invention relates to a sleeve retainer for an extension rod drilling apparatus comprising - a frame mountable on a feeding beam of the drilling apparatus, - two jaw arms mounted coaxially and pivotably on said frame and provided with jaws facing each other, and - a pressure-fluid operated actuating means connected to said jaw arms so that said arms are pivotable to a gripping position, in which said jaws form a gap which can be pressed against a connection sleeve of a drill rod, and to an open position, in which said jaws are displaced away from each other in order to open said gap.

A sleeve retainer of this type is used in longhole drilling for maintaining the connection sleeve unrotatable when the drill shank of the drilling machine is turned loose from the sleeve for removing the drill rod.

In known extension rod drilling apparatuses the connection sleeve of the drill rod is, when discoupling the drill rods, maintained in engagement with the rod by braking the sleeve eccentrically while at the same time turning the shank loose from the sleeve. However, this procedure involves some disadvantages. Because the sleeve is braked eccentrically, the braking tends to push the sleeve against the thread of the shank, which causes locking of the thread and hampers the opening. In addition, the braking of the sleeve may cause a disengagement of the sleeve simultaneously both from the drill rod and the shank whereby the sleeve falls down and involves a safety hazard for the driller.

From the Swedish Printed Specification 391,770 is known a sleeve brake intended to be mounted at the front end of a drilling machine. The sleeve brake includes a pivotable long arm which supports a link provided with flexibly fastened jaws. When it is desired to disengage the drill sleeve, the link is by means of the arm pivoted upon the drill sleeve in order to lock it unrotatably.

By means of this device only hexagonal drill sleeves can be locked and its use, in addition, requires a large space around the machine.

The object of the present invention is to provide a sleeve retainer which avoids the above mentioned disadvantages and permits an automatic centering of the jaws around the sleeve.

This object is achieved by means of a sleeve retainer according to the invention which is characterized in that said actuating means is connected to said jaw arms so that the jaw arms and the actuating means form a unit freely pivotable around the pivot shaft of the jaw arms with respect to said frame.

The invention is based on the idea that, by connecting the actuating means to act only between the jaw arms, the actuating means does not prevent a simultaneous pivoting of the jaw arms on their shaft with respect to the frame.

When the jaw arms and the actuating means are aliowed to pivot as one unit, both jaw arms can automatically correct their positions around the sleeve when the jaws are closed under the action of the actuating means so that the jaws are precisely centered with respect to the axis of the sleeve while the actuating means presses the jaw arms against the sleeve. Due to this, no radial stress is applied on the threads of the sleeve and the drill shank whereby the thread opens more easily and is subjected to less wear. By means of the sleeve retainer sleeves of all shapes can be locked, and it does not require any large space of operation. A further advantage is that the connection sleeve cannot fall down accidentally because the jaws hold it during the entire disengagement.

The invention will be described in more detail in the following with reference to the accompanying drawing, in which Figure 1 is a schematic side view of an extension rod drilling apparatus provided with a sleeve retainer according to the invention, Figure 2 is a side view on an enlarged scaie of the sleeve retainer, Figures 3 and 4 are end views of the sleeve retainer in the gripping position and in the open position, respectively, and Figures 5 and 6 illustrate schematically two alternative embodiments of the sleeve retainer.

in Figure 1 of the drawings is shown an extension rod drilling apparatus comprising a drilling machine 1 displaceable by means of a feed mechanism (not shown) along a feeding beam 2.

The feeding beam supports a sleeve retainer 3 and a drill guide 5 for a drill rod 5 connected by means of a connection sleeve 6 to a drill shank 7 of the drilling machine.

The sleeve retainer 3 comprises a frame 8 provided with a support plate 9 and an upwardly directed support 10 fastened to said support plate.

The support plate is intended to be mounted in a conventional manner by'means of guide means (not shown) longitudinally siidably on rails on the feeding beam 2.

The support 10 supports a pivot shaft 11 on which are pivotably mounted two jaw arms 12, 1 3 located cross-wise in a scissor-like manner. Both jaw arms are formed by double-armed levers at the inner ends of which are fastened replaceable jaws 14 which form generally arc-shaped gripping surfaces 1 4a. The radii of curvature of said .surfaces substantially correspond to the radius of curvature of the cylindrical outer surface of the connection sleeve. The gripping surfaces of the jaws have, in the gripping position of the jaw arms shown in Figure 3, a common centre of curvature whereby the surfaces form a cylindrical gap for the connection sleeve. The axis A of said gap passes through the centre of curvature and is parallel with the pivot shaft 11 of the jaw arms.

The outer ends of the levers forming the jaw arms 12, 13 are connected to the cylinder and the piston rod, respectively, of a hydraulic actuating means mounted therebetween by means of pivot shafts 1 6 and 17, respectively. The pressure fluid connections of the cylinder are indicated by the reference numeral 1 8. The arrangement is such that the actuating means is able to pivot the jaw arms between the gripping position shown in Figure 3 and the open position shown in Figure 4.

The frame 8 is intended to be mounted on the raiis of the feeding beam 2 so that the axis A of the cylindrical gap formed by the jaws coincides with the axis B of the drill rod 5 coupled by means of the connection sleeve 6 to the drill shank 7, i.e.

with the drilling axis, Figure 1.

The sleeve retainer operates in the following manner: When it is desired to disengage the drill shank from the sleeve, the jaw arms are pivoted by means the actuating means to the gripping position to press the jaws from opposite sides against the sleeve. Due to the fact that the jaw arms pivot around the same shaft and the actuating means acts only between the jaw arms and is not at all supported by the frame, the jaw arms and the actuating means together form a freely pivotable unit whereby the jaws are automatically centered around the sleeve axis as they are pressed against the sleeve. When the sleeve has been locked in this way, the drill shank is rotated in a thread-opening direction.

The jaw arms are opened by pivoting the arms by the actuating means to the open position.

Alternatively, the counter-pressure of the hydraulic circuit of the actuating means may carry out the pivoting of the jaw arms to the open position when the operating pressure of the actuating means is disconnected.

In the free position of the control valve of the actuating means the counter-pressure of the hydraulic circuit, a spring or similar keeps the jaw arms in the open position supported against shoulders 1 9 and 20 so that the vibrations of the drilling machine and the feeding beams are prevented from freely striking the jaw arms against the shoulders whereby the durability of the construction and the bearings is improved.

The sleeve retainer 3 is connected to the drilling machine by means of a flexible coupling 21 comprising a rod 22 which is parallel with the feeding beam and is slidably mounted in a support 24 fastened to the sleeve retainer and in a support 25 fastened to the drilling machine. The rod is provided with three springs 26 located between both supports and between each support and a stop at the end of the rod, respectively.

Such a coupling permits a displacement of the sleeve retainer along with the drilling machine and also permits a displacement of the sleeve retainer with respect to the drilling machine. Due to this, the drilling machine can be fed backwards when opening the thread of the shank while the sleeve retainer remains stationary, whereby the sleeve retainer does not resist an axial movement between the sleeve and the shank when the thread is opened.

The alternative embodiments shown in the Figures 5 and 6 differ from the one shown in the Figures 2 to 4 only with respect to the mounting of the jaw arms.

The drawings and the description relating thereto are only intended to illustrate the idea of the invention. In its details the sleeve retainer according to the invention may vary within the scope of the claims.

Claims

1. A sleeve retainer for an extension rod drilling apparatus comprising - a frame (8) mountable on a feeding beam (2) of the drilling apparatus, - two jaw arms (12, 13) mounted coaxially and pivotably on said frame and provided with jaws (14) facing each other, and - a pressure-fluid operated actuating means (1 5) connected to said jaw arms so that said arms are pivotable to a gripping position, in which said jaws form a gap which can be pressed against a connection sleeve (6) of a drill rod (5), and to an open position, in which said jaws are displaced away from each other in order to open said gap, characterized in that said actuating means (1 5) is connected to said jaw arms (12, 13) so that the jaw arms and the actuating means form a unit freely pivotable around the pivot shaft (11) of the jaw arms with respect to said frame (8).

2. A sleeve retainer according to claim 1, characterized in that said jaw arms (12, 13) comprise double-armed levers, that said jaws (14) are located at adjacent ends of said levers, and that said actuating means (1 5) is connected to the opposite ends of said levers.

3. A sleeve retainer according to claim 2, characterized in that said jaw arms (12, 13) are mounted crosswise in a scissor-like manner.

4. A sleeve retainer according to claim 1, characterized in that said jaw arms (12, 13) are single-armed levers, that said jaws (14) are located at adjacent ends of said levers, and that said actuating means (15) is connected to points positioned between the ends of each lever.

5. A sleeve retainer according to claim 1, characterized in that said jaw arms (12, 13) are mounted in said frame (8) by means of a common pivot shaft 1).

6. A sleeve retainer according to claim 1, characterized in that said jaw arms (12, 13) are provided with separate jaws (14) forming arcshaped gripping surfaces (1 4a), the radii of curvature of said surfaces substantially corresponding to the radius of curvature of the cylindrical outer surface of said connection sleeve (6).

7. A sleeve retainer according to claim 1, characterized in that said frame (8) is provided with stops (19, 20) against which said jaw arms (12, 13) abut in said open position under the action of a counter-pressure of said actuating means (15), a spring, or similar.

8. A sleeve retainer according to claim 1, characterized in that said frame (8) is provided with a flexible coupling (21) by means of which the frame is connectable to said drilling machine (1) for resilient displacement along with said machine and with respect to said machine.