HYDRAULIC BREAKING HAMMER

Abstract: A hydraulic breaking hammer (10) comprises a machine housing (11) in which an impact piston (17) moves reciprocatingly. The breaking tool (18) is carried releasably in a tool part (16) fitted on the forward part of the machine housing (11). A transverse slot (23) intersects the cylinder bore (12) in the machine housing (11) outside forwardly located impact-piston hydraulic seals and forms mutually opposing, forwardly directed sidewall parts (22) on the machine housing (11). The tool part (16) has located rearwardly thereon a head (17) which is insertable into the lateral slot (23) between the sidewall parts. The head (17), and therewith the tool part (16), can be locked in this position to the machine housing (11) with the aid of retainers (26, 27) insertable in coaxial lateral bores (19, 20) in the sidewall parts (22) and in the head (17). The head (17) has impact-damping plastic bushes (29) which fit around the retainers (26, 27), and the transmission of impact forces from the head (17) to the machine housing (11) is prevented by virtue of a gap (40) at the bottom of the lateral slot (23).

Description: HYDRAULIC BREAKING HAMMER The present invention relates to hydraulic breaking hammers of the kind that comprise a machine housing which includes a cylinder bore and a reciprocatingly movable impact piston which moves backwards and forwards in said passage in response to alternating hydraulic pressure, a tool part which is fitted to the front of the machine housing and which has a guide bore which lies in line with the cylinder bore and in which a breaking tool is slidably carried and repeatedly subjected to impact by the impact piston as it moves, support means for aligning the breaking hammer mechanically in operation, and sealing means arranged in the front of the machine housing between the cylinder bore and the impact piston and functioning to separate the drive hydraulics of the breaking hammer from the tool part. Breaking hammers of this kind are normally mounted on hydraulically operated carriers of different sizes, wherein the carrier hydraulics are also coupled to drive the breaking hammer, and wherein the breaking hammer is pivotally mounted on the outer end of a boom via the supports on said housing so as to be positioned mechanically by said boom in opera¬ tion. The machine housing of the breaking hammer is typically comprised of separate cylinder parts which embrace the impact piston, the seals and the valve system, and which are grouped axially in juxtaposed relationship and held tightly together by robust side bolts, so as to ensure that a seal is obtained between the cylinder parts against the high internal hydrau¬ lic working pressures. Side bolts and other screw fastener means, however, have certain drawbacks. The screw threads are shaken loose. In the case of side bolts, the wear and the corrosion that occurs in operation, together with micro- movements in the joints as a result of impacts and vibrations generated in the breaking hammer, cause the joints of the cylinder parts and their seals to be attacked by penetrating pressure oil and leakages and ultimately result in conditions which are hazardous both to the surroundings and to people in the vicinity of the work being carried out. Side bolts can also fracture, with serious consequences. In recent times, this insight into the hazards of side bolts has led to an endeavour to exclude side bolts from breaking hammer con¬ structions. An example of one such endeavour is disclosed in International Publication WO 93/22106, PCT/SE93/00382. Lightweight automotive carriers and short breaking hammers have been used in the demolition of derelict buildings, so as to be able to enter confined spaces more easily and to work therein more effectively. The hydraulic part of the machine housing forms the rear part of the breaking hammer and can therewith readily be made short and sufficiently robust to provide a long useful life, in the absence of side bolts. However, indoor demolition work results in an increase in laterally acting impacts, blows and breaking action, particularly against the breaking tool and against the tool part at the front of the housing, such that after being in operation for some length of time, the entire machine housing may be judged to be ineffective due to damage to the tool part. This is highly disadvantageous from the cost aspect, in view of the fact that the hydraulic part of the tool is expensive to produce and cannot be considered as being a spare part. With regard to hydraulic breaking hammers of the type concerned here, an object of the invention is to provide a breaking hammer which is better adapted for indoor demolition work and which has a front part or tool part which eliminates the need for side bolts and which also enables the longer useful life of the hydraulic part mounted in the machine housing to be used more effectively. The novel design of the tool part also enables the tool part to be exchanged quickly and easily when servicing the hammer, and also provides for O 96/15881 PCI7SE95/01370 better accessibility to the interior of the machine housing and reduces the centering requirement between the tool part and the machine housing. The novel mounting of the tool part in the machine housing also enables transmission of impact forces from the tool part to the machine housing to be dampened during hammer operation. The invention will now be described in more detail with reference to the accompanying drawings, in which Fig. 1 illustrates an inventive breaking hammer from above; Fig. 2 is a cross-sectional view taken on the line 2-2 in Fig. 1; Fig. 3 is an isolated view of the tool part in Fig. 1 from above; Fig. 4 is a side view of the tool part shown in Fig. 3; Fig. 5 is a longitudinal section view taken on the line 5-5 in Fig. l; and Fig. 6 is a view corresponding to Fig. 2 illustrating a modification of the tool part attachment. The breaking hammer 10 shown in Fig. 1 includes a machine housing 11 and a tool part 16 which is fitted to the front of the housing 11. The tool part slidably carries a breaking tool 18, which is detachably retained in the guide bore 21 of said tool part 16 by means of locking retainers 33 (Fig. 5) and which has limited axial movement in the guide bore 21. The locking retainers 33 coact with recesses 35 provided in the breaking tool 18, and are insertable into lateral bores 34 in the tool part 16. The machine housing 11 carries at its rear end two supports 25 which include bores, indicated at 32, for pivotal connection to an automotive carrier (not shown) , conveniently a lightweight carrier for building demolition purposes, and with a hydraulically operable boom for mechanical alignment of the breaking hammer 10 in the process of its work. The tool part 16 has a pointed or tapering configuration which enables the tool to work effectively and to reach into confined corners in demolition and cleaning operations. The machine housing 11 also contains a cylinder bore 12 and a reciprocatingly movable impact piston or ram 15 which moves backwards and forwards in said bore in response to alternat¬ ing hydraulic pressures delivered through the medium of a distributing valve bore 14, Fig. 5. The hydraulics used to drive the impact piston may have, in principle, any suitable known design, for instance may be slide-guided as described in the aforesaid publication WO 93/22106 and need not therefore be described here. The breaking hammer hydraulics are mounted in the interior of the machine housing and are held separate from the tool part 16 by sealing means 13 provided at the front end of the machine housing 11 and disposed around the front end of the impact piston 15. The cylinder bore 12 is sealed-off at its rear end by means of a cover plate 37 bolted to the rear end of the housing 11. The housing 11 is robust and made in one single piece from cast iron, including the supports 25. Similar to the cover plate 37, the tool part 16 is carried by the machine housing 11 without the aid of side bolts or any other vibration-sensitive screw-threaded devices. To this end, the forward part of the machine housing 11 forms mutually parallel and mutually opposing side-wall parts 22 between which there extends a lateral slot 23 which inter¬ sects the cylinder bore 12 forwardly of the sealing means 13. Rearwardly of the locking retainers 33, the tool part 16 forms a head 17 which extends transversely to the guide bore 21 and which fits slidingly in and can be inserted between the side-wall parts 22, so that the guide bore 21 will be in alignment with the cylinder bore 12. The head 17 is provided with through-penetrating lateral-bores 20 on each side of the guide bore 21, and the side-wall parts 22 include lateral- bores 19 which are located coaxially with the lateral-bores 20 when the head 17 is fitted between the side-wall parts 22. When retainers 26, 27 are inserted through the lateral-bores 19, 20, there is obtained a robust attachment of the tool part 16 to the machine housing 11, wherein the tool attach¬ ment can be made and unmade both quickly and easily. In a simplified form, the lateral-bores 19, 20 can be made identical to one another and accommodate single retainers or, as indicated in Fig. 1, lengthwise divided retainers in direct metal to metal contact in the lateral-bores 19, 20 of the side-wall parts 22 and the head 17, as shown in Figs. 2 and 6. However, the retainer attachment between the aforesaid parts can be used very conveniently to dampen vibrations. In this regard, the retainers 26, 27 are fitted with impact- damping plastic sleeves 29, at least in the lateral-bores 20 in the head 17, these lateral-bores being given a slightly larger diameter than the lateral-bores 19 so as to provide room for the sleeves 29. The sleeves will preferably be made of polyurethane, which affords a good vibration damping effect. It will be seen from Figs. 1 and 5 that when the tool part 16 is inserted and secured by the retainers, gaps 39, 40 are formed between the bottom of the lateral slot or channel 23 and adjacent side-wall parts 22 and the head 17 and its adjacent end-walls 38. Due to the vibration-space in the gaps 39, 40, the plastic sleeves 39 are able to dampen occurrent impacts and prevent the transmission of impact forces to the machine housing 11 as a result of direct metallic contact. In the case of the Fig. 2 embodiments, the retainers are cylinder and are slit along an undulating line 36 so as to form tensioning bushes 26 which press against the lateral- bores 19 and secure the retainers longitudinally against being shaken out from the bores while the hydraulic breaking hammer is in use. The retainers are preferably made from steel and are radially resilient. In the case of the Fig. 6 embodiment, the solid steel retainers 27 include a circular groove 30 in the region of the sleeves 29. Correspondingly, the sleeves 29 are provided with an internal bead 31 which springs into the circular groove as the retainers 27 are fitted. Due to the differences in the diameters of the cross-bores 19, 20, the sleeve 29 and its bead 31 will hold the retainers 27 locked in position in the head 17 of the tool part 16 located between the side-wall parts 22 of the machine housing 11. It will be observed that the construction does not require the impact piston 17 to be accurately centered in the guide bore 21 of the tool part 16. The impact piston 15 may simply lie in the guide bore and repeatedly strike against the breaking tool 18 with free play in said guide bore 21, to no disadvantage.

Claims: CLAIMS 1. A hydraulic breaking hammer (10) comprising a machine housing (11) which includes a cylinder bore (12) and a reciprocatingly movable impact piston (15) which moves backwards and forwards in said passage in response to alternating hydraulic pressure, a tool part (16) which is fitted to the front of the machine housing (11) and which has a guide bore (21) which lies in line with the cylinder bore (12) and in which a breaking tool (18) is slidably carried and repeatedly subjected to impact by the impact piston (15) as is moves, support means (25) for aligning the breaking hammer (10) mechanically in operation, and sealing means (12) arranged in the front of the machine housing (11) between the cylinder bore (12) and the impact piston (15) and functioning to separate the drive hydraulics of the breaking hammer from the tool part (16) , characterized in that the machine housing (11) forms forwardly thereof between mutually opposing side¬ wall parts (22) a lateral slot (23) which intersects the cylinder bore (12) forwardly of the sealing means (13) and into which a head (17) provided rearwardly of the tool part (16) can be inserted and locked to the machine housing (11) by means of a pair of retainers (26, 27) inserted in lateral- bores (19, 20) that extend through the side-wall parts (22) and the head (17) on both sides of the tool-part guide bore (21). 2. A breaking hammer according to Claim 1, characterized in that the retainers (26, 27) are fitted with impact-damping plastic sleeves (29), preferably polyurethane sleeves, at least between said retainers and the head (17) of the tool part (16), and in that when the tool part (16) is locked to the machine housing (11) one or more gaps (39, 40) which prevent the transmission of impact forces metal against metal is/are formed between the mutually opposing surfaces of the machine housing (11) and the tool part (16). 3. A breaking hammer according to Claim 2, characterized in that the diameter of the lateral-bores (19, 20) in the head (17) of the tool part (16) is greater than the diameter of the lateral-bores in the side-wall parts (22); and in that said impact damping plastic-sleeves (29) , preferably polyure¬ thane sleeves, are fitted around the retainers (26, 27) in the head (17) . 4. A breaking hammer according to Claim 3, characterized in that the retainers have the form of hollow cylinder bushes (26) which are slotted along an undulating line (36) and which exert a radially and outwardly acting force when fitted. 5. A breaking hammer according to Claim 3, characterized in that the retainers (27) are solid and have a circular groove (30) in the region of the plastic sleeves (29), and in that the plastic sleeves (29) are provided internally with a bead (31) which springs into the circular groove (30) when fitted to respective retainers and therewith lock the retainers (27) between the side-wall parts (22). 6. A breaking hammer according to Claim 1, characterized in that the tool-part guide bore (21) accommodates the impact piston (17) with a given clearance or play. 7. A breaking hammer according to Claim 1, characterized in that the front part of the tool part (16) includes at least one lateral-bore (34) for detachably receiving a locking retainer (33) which in coaction with lateral recesses (35) on the breaking tool lock the breaking tool (18) in the tool part (16) while limiting axial movement of the breaking tool in said tool part. 8. A breaking hammer according to Claim 2, characterized in that the gaps (39, 40) are formed at the bottom of the lateral slot (23) and, when necessary, adjacent the side-wall parts (22).

Inventors: HENRIKSSON ROLAND, HENRIKSSON, ROLAND
Applicants: BEREMA ATLAS COPCO AB, HENRIKSSON ROLAND, ATLAS COPCO BEREMA AKTIEBOLAG, HENRIKSSON, ROLAND
Application year: 1995
Main classification: B25D17
IPC codes: B25D17