GB2147686A

GB2147686A - Rotary hammer friction coupling

Info

Publication number: GB2147686A
Application number: GB08421570A
Authority: GB
Inventors: Jury Niktovich Kolgan; Sergei Anatolievic Sapozhnikov; Vladimir Porfirievich Balandin; Ivan Andreevich Prokhorov
Original assignee: VNI I PK I MEK VANNAGO I RUCHN
Current assignee: VNI I PK I MEK VANNAGO I RUCHN
Priority date: 1983-09-02
Filing date: 1984-08-24
Publication date: 1985-05-15
Also published as: GB8421570D0; ATA209984A; GB2147686B; CS372184A1; SE8403432L; CS263461B1; DE3423726A1; SU1209840A1; YU123284A; CH665256A5; DD254305A3; AT385813B; SE8403432D0

Abstract

A rotary hammer comprising a casing (1) accommodating a rotary drive (2) having a protective clutch in which one of the clutch members (5) has a non-round hole (6) and mounts an adjusting nut (8) and a bushing (13) with a non-round hole (14), the hammer drill also comprising a removable key (21) for adjusting the torque of the protective clutch, the key having a shaft (22) having a non-round portion (24) at the end thereof and corresponding to the non-round hole (6) and a sleeve (25) surrounding the shaft (22) which also has a non-round portion (26) corresponding to the non-round hole (14) of the bushing (13). <IMAGE>

Description

SPECIFICATION Rotary hammer The invention relates to the mechanical engineering, and in particular to hammer and rotary drilling machines, such as rotary hammers which are designed for use in the construction and mining industries and in geological explorations.

Known in the art is a rotary hammer (cf. US patent No. 3396557, 1968), comprising a rotary drive for rotating a working tool, including a protective clutch in which one clutch member has a shaft with a threaded shank protruding outside the rotary hammer casing and having a nut to which is secured an arm cooperating with a spring of the protective clutch.

In this prior art rotary hammer, the protective clutch torque is adjusted by turning the arm disposed outside the casing and connected to the clutch member by means of an adjusting nut.

These rotary hammers are, however, insufficiently reliable in operation because they have parts protruding outside the casing so that accidental shocks may result in damages to the rotary hammer. This disadvantage also impairs sealing of the interior of the rotary hammer casing.

Also known in the art is a rotary hammer (cf. US patent No. 3837409, 1974), comprising a rotary drive accommodated in the casing and having a protective clutch including a first clutch member, a second clutch member with a non-round hole, an adjusting nut installed on the second clutch member, and a retainer for holding a working tool against rotation.

The rotary hammer also has a removable key for adjusting the slip torque of the protective clutch and a retaining key for holding one of the clutch members against rotation.

The adjusting nut in this rotary hammer comprises a gear and rotary hammer casing has an opening which is sealed by means of a threaded plug. The opening is made in such a manner that the key, which is cylindrical and has a non-round portion made in the form of a gear, is inserted into the opening so as to mesh with the gear of the adjusting nut.

In this prior art rotary hammer the clutch member is first prevented from rotating by means of the retaining key received in the hole of a gear which transmits rotary motion to the shank of the working tool and which is connected to said clutch member through a gearing.

Torque transmitted by the protective clutch is adjusted by the removable key by turning the adjusting nut which is installed on the other clutch member.

To set a desired torque of the protective clutch, the retaining key is inserted into the casing of the rotary hammer to retain the first clutch member against rotation. Then the plug is removed from the casing to have access to the protective clutch, and the removable key is inserted into the opening to engage the adjusting nut. The adjusting nut is caused to rotate relative to the second clutch member by turning the removable key to deform a spring which determines the force pressing together friction plates of both clutch members, whereby the torque transmitted by the protective clutch is adjusted.

Maintenance and operation of this prior art rotary hammer are difficult since for adjusting the ultimate torque of the protective clutch four different members should be manipulated: the removable key, the retaining key, the rotary hammer and the plug.

in addition, this prior art rotary hammer is not sufficiently reliable since the interior of the rotary hammer is unsealed upon removal of the plug for adjusting the protective clutch, which may result in oil leakage and increased wear of working members of the rotary hammer.

It is an object of the invention to facilitate operation and maintenance and improve reliability of the rotary hammer.

This is accomplished by that a rotary hammer comprising a rotary drive accommodated in the casing and including a protective clutch having a first clutch member, a second clutch member with a non-round hole and an adjusting nut installed on this clutch member, a removable working tool, a retainer for holding the working tool against rotation and a removable key having a shaft with a non-round portion at the end thereof, according to the invention, is provided with a bushing with a non-round hole which is rotatably mounted on the second clutch member, the bushing being connected for combined rotation with the adjusting nut, the removable key is provided with a sleeve surrounding the shaft, loosely fitted thereon and having a non-round portion corresponding to the non-round hole of the bushing, the sleeve also having on the outer surface thereof a profiled portion for receiving the working tool retainer.

Therefore, according to the invention, the rotary hammer has a casing accommodating a rotary drive comprising a protective clutch having a second clutch member on which is rotatably mounted a bushing engaging the adjusting nut. In addition, the clutch member and the nut have respective non-round holes. The removable key is in the form of a shaft and a sleeve surrounding the shaft, both the shaft and the sleeve having non-round portions on their outer surfaces. When the removable key is inserted into the casing, it engages the respective holes of the second clutch member and the bushing. The sleeve is at the same time retained against rotation in the casing by the working tool retainer. By turning the shaft the adjusting nut is caused to rotate relative to the second clutch member, whereby torque transmitted by the protective clutch may be changed.The invention makes it possible to adjust torque transmitted by the protective clutch using a single removable key which performs simultaneously two operations: rotation of the adjusting nut relative to the second clutch member and holding of one of these elements against rotation relative to the casing, whereby the maintenance and operation of the rotary hammer are facilitated.

These and other advantages will become apparent from the following detailed description of a particular embodiment of the invention with reference to the accompanying drawings, in which: Figure 1 shows a rotary hammer (without a drive motor) in a sectional view in the area of insertion of a working tool, according to the invention; Figure 2 is a sectional view of a rotary drive of the rotary hammer taken along the line ll-ll in Figure 1; Figure 3 is a removable key according to the invention; Figure 4 is a longitudinal sectional view of the removable key taken along the line IV-IV in Figure 3; Figure 5 is a transverse sectional view of the removable key taken along the line V-V in Figure 4; Figure 6 shows the rotary hammer with the removable key inserted therein shown in the position in which it engages the second clutch member, according to the invention;; Figure 7 shows the rotary hammer with the removable key inserted therein in the position in which it engages the second clutch member and the bushing connected to the adjusting nut, according to the invention; Figure 8 is a transverse sectional view of the rotary hammer taken along the line Vlil-Vlli in Figure 7, according to the invention.

A rotary hammer according to the invention comprises a casing 1 (Figure 1 j in which is accommodated a rotary drive 2 including a protective clutch 3 with a first clutch member in the form of gears 4 and a second clutch member in the form of a bushing 5 having a non-round, e.g. hexagonal hole 6, which is operatively connected to friction plates 7. The protective ciutch 3 also has an adjusting nut 8 having flats 9 (Figure 2) and installed on the bushing 5 by means of a threaded joint. For setting-up a desired torque of the protective clutch 3 (Figure 1) by rotating the adjusting nut 8, springs 10 are provided on the bushing 5. The gears 4 are operatively connectible with one of the steps of a gear 11 which is installed on a shaft 12 of the rotary drive 2.

A bushing 13 having a non-round hole 14 of hexagonal cross-section is rotatably mounted on the bushing 5, the cross-section of the hole in this embodiment being larger than the cross-section of the non-round hole 6 of the bushing 5. The non-round hole 14 may have the cross-section equal to the cross-section of the non-round hole 6 of the bushing 5. The bushing 13 is operatively connected in the radial direction with the adjusting nut 8 by means of projections 15 engaging the flats 9 (Figure 2). A gear 16 (Figure 1) installed between the bushing 13 and the casing 1 for free rotation is operatively connected to the other step of the gear 11 of the rotary drive 2.

The casing 1 has a hole 17 coaxial with the bushing 5, bushing 13 and gear 16 for the insertion of a working tool 18 which has a profiled portion 19 for cooperating with a retainer 20 installed in the casing 1. When the working tool 18 is fully inserted, the retainer 20 holds it against rotation with respect to the casing 1 as shown in Figure 1. For adjusting the torque transmitted by the protective clutch 3, there is provided a removable key 21 (Figure 3) having a shaft 22 with a handle 23. At the end of the shaft 22 there is a non-round portion 24 (hexagonal in this embodiment) (Figure 4). The key 21 has a sleeve 25 surrounding the shaft 22, which is loosely fitted thereon for rotation and which has a non-round portion 26 (Figure 5) in the form of a hexahedron adjacent to the non-round portion 24 of the shaft 22 corresponding to the non-round hole of the bushing 13 (Figure 1).

The rotary hammer functions in the following manner. When it is necessary to change the torque transmitted by the protective clutch 3, the retainer 20 should be set in a position in which the shape of the hole 17 of the casing 1 does not hamper the insertion of the working tool 18 or the key 21 (Figure 6), and for that purpose the retainer 20 is turned (Figure 8). Then the removable key 21 is inserted into the hole 17 in such a manner that the portion of the shaft 22 having the hexagonal crosssection 24 is received in the non-round (hexagonal) hole 6 of the bushing 5 and moves along into the interior of the casing until the sleeve 25 bears against the bushing 13. Thus the end face of the portion 26 of the sleeve 25 bears against the bushing 13.The sleeve 25 is held against rotation, and the shaft 22 is turned by the handle 23 to rotate the adjusting nut 8 and bushing 13 so as to bring in registry the hexagonal hole 14 of the bushing 13 with the hexagonal portion 26 of the sleeve 25, and then the sleeve 25 is pushed into the casing 1 until it bears again against the bushing 13 (Figure 7). In this case the protruding portion of the sleeve 25 which is behind the portion 26 (Figure 4) will bear against the bushing. In this position both the sleeve 25 and the bushing 13 engage one another in the radial direction. Then the removable key 21 is turned until the profiled portion 27 of the sleeve 25 is positioned opposite to the retainer 20, and the retainer is set so as to hold the sleeve 25 against rotation in the casing 1 (Figure 8).After the sleeve 25 (Figure 7), the bushing 13 and the adjusting nut 8 are set in the position in which the adjusting nut 8 is prevented from rotating with respect to the casing 1, the removable key 21 is used to rotate the bushing 5 clock - or counterclockwise depending on the hand of the threaded joint between the adjusting nut 8 and bushing 5.

The springs 10 are thus deformed so as to obtain a necessary compression force between the clutch members and a desired torque of the protective clutch 3.

Owing to the fact that the rotary hammer is provided with the bushing 13 rotatably mounted on the second clutch member in the form of the bushing 5, the bushing 13 meshes with the adjusting nut 8, and the removable key 21 is made in the form of an integral unit which provides for holding the adjusting nut 8 against rotation and for simultaneous rotation with respect to it of the second clutch member, the maintenance and operation of the rotary hammer are facilitated and the working space of the rotary hammer need not be unsealed.

The rotary hammer according to the invention makes it possible to adjust torque of the protective clutch using a single removable key so that the number of elements required for the adjustment of the protective clutch is reduced. This construction of the rotary hammer makes it possible to reduce the number of operations for adjustment of the clutch torque thus materially facilitating the maintenance and operation of the rotary hammer. The maintenance time is thus reduced and the productivity of the rotary hammer may be improved.

Claims

1. A rotary hammer having a casing in which are accommodated a rotary drive including a protective clutch including a first clutch member, a second clutch member with a non-round hole, an adjusting nut and a bushing with a non-round hole installed for rotation on the second clutch member and connected to each other, a removable working tool, a retainer for holding the working tool against rotation, and a removable key for adjusting the limit torque of the protective clutch, the key having a shaft with a non-round portion at the end thereof and a sleeve surrounding the shaft, loosely fitted thereon and having a non-round portion corresponding to the non-round hole of the bushing, the sleeve having on its outer surface a profiled portion for receiving the working tool retainer.

2. A rotary hammer substantially as hereinabove described with reference to, and as shown in, the accompanying drawings.