ROTARY IMPACTING APPARATUS

Abstract: A rotary impacting apparatus comprises rotary member (2) drivingly rotated about a rotational axis (O) within a casing (1). An impact member (11) is loosely held by the rotary member so as to be movable toward and away from the rotational axis within a limited range. A holder (14) mounted to the casing slidably supports a reciprocative member (16) to allow movement thereof toward and away from the rotational axis within a limited range. The reciprocative member has a contact surface (16c) which interferes with the impact member rotating about the rotational axis when the reciprocative member is positioned closest to the rotational axis.

Description: This invention relates to a rotary impacting apparatus according to the preamble of claim 1, which is known from US-A-16 32 255. As is well known, impacting-apparatuses have various applications. Chiefly, they can be used to break hardened concrete or asphalt solids at construction sites by using a chisel as a working tool. By selecting suitable working tools, they can also be used to drive piles into grounds or to stamp loose grounds or uncured asphalt pavements. Conventional impacting apparatuses, particularly solids breakers, can be classified mainly into two types, that is, compressor operated type and engine operated type. A typical breaker of the compressor operated type comprises a a vertically extending cylindrical main body connected to an air compressor through pressure hoses, and a piston reciprocated up and down within the main body by expansion of compressed air supplied to the main body from the compressor. Upon each downward stroke, the piston hits a chisel provided at the lower end of the main body. With the compressor operated breaker, the piston must be repetitively accelerated and decelerated against its inertial mass, so that it is difficult to achieve a high impacting frequency and to avoid vibration resulting from such reciprocation. Further, because of sliding reciprocation of the piston with resultant heat generation, the cylindrical main body must be made of a tough and heavy material, consequently making large the total weight of the apparatus including the compressor (also heavy). More importantly, the compressor is very high in energy consumption. On the other hand, a typical breaker of the engine operated type is disclosed for example in UK Patent No. 1,358,674. Specifically, the breaker of this patent comprises a vertically extending cylindrical main body in which a movable cylinder is slidably reciprocated up and down by an engine connected thereto via a crank mechanism. A free piston is slidably guided within the movable cylinder and divides the interior thereof into two pressure chambers. The free piston has an impact rod hermetically projecting downward through an end wall of the movable cylinder. When the movable cylinder is reciprocated, the two pressure chambers are alternately compressed by inertial delay of the free piston to reciprocate the piston upon subsequent expansion of the pressure chambers. On each downward stroke of the piston, the impact rod hits a chisel provided at the lower end of the main body. The engine operated breaker needs no compressor, so that it is much higher in energy efficiency. However, the use of the movable cylinder and the free piston, which are reciprocating parts, is disadvantageous in view of unacceptable vibration, limitation on achievable impacting frequency, and inevitable weight increase, as described with respect to the compressor operated breaker. Further, the engine operated breaker requires a number of components in a complicated arrangement. Both types of prior art breakers or impacting apparatuses rely on air compression and expansion as well as on gravity acting on the piston and/or the movable cylinder. Therefore, the prior art impacting apparatus cannot be used in a non-atmospheric or non-gravitational condition, that is, in the space. This is of great disadvantage in view of recent space developments. Moreover, reliance on gravity poses a difficulty in operating the apparatus in a horizontal or upwardly directed posture. There is, therefore, a need to provide an impacting apparatus which, with a small number of components and with a light weight, can be used even in a non-gravitational and/or non-atmospheric condition and in any posture, and which is capable of achieving high impacting frequency. The invention seeks to provide a rotary impacting apparatus which can be operated with reduced vibration and heat generation and which is minimized in overall weight. According to the invention, there is provided a rotary impacting apparatus according to the preamble of claim 1, which is specified by the characterizing features (a) and (b) thereof. Further advantageous embodiments are characterized in dependent claims 2 through 5. Advantageously, forming said impact member as a cylinder with a constant cross-section along its entire length is technically significant in that the weight of the impact member can be increased to increase the impact energy without virtual dimensional modifications and without need for providing diametrically different shaft portions. Further, the close sliding fit prevents objectionable lateral dancing of the impact member resulting in vibration, whereas non-rolling of the impact member relative to the housing prevents a considerable energy loss, heat generation and noises. From US-A-22 33 913, it is known for obviating friction drag and retarding the driving member and the supporting carrier to provide a resting means limiting the radial movement of the impact member away from the rotational axis by providing a hole having a greater diameter than said impact member, wherein said impact member is formed by a cylinder element having different circular cross-sections along its length. The invention will now be described further, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a sectional side view of a rotary impacting apparatus according to a first embodiment of the invention; Figure 2 is a sectional view taken on lines X-X in Figure 1; Figure 3 is a perspective view showing an automatic shovelling device incorporating a rotary impacting apparatus according to a second embodiment of the invention; Figure 4 is an enlarged sectional view taken on lines XII-XII in Figure 3; and Figure 5 is an enlarged sectional view taken on lines XIII-XIII in Figure 3. The present invention may provide various applications other than breaking solids. For example, the invention may be used for pile driving, as illustrated in Figures 1 and 2. Referring to Figures 1 and 2, a small engine 23 is mounted on a casing 1 which rotatably accommodates an elongated rotary member 2'. The engine 23 has an output shaft 24 drivingly connected to one shaft 3 of the rotary member 2' by means of pulleys 25, 26 and a belt 27. The elongated rotary member 2' includes a pair of side flanges 2a', 2b' connected by a shaft-like intermediate portion 2c'. The respective side flanges 2a', 2b' are provided with corresponding elongated holes 10a', 10b' extending toward the rotational axis O of the rotary member 2' for receiving a columnar impact member 11. Therefore, the impact member 11 is rotatable about its own axis and movable toward and away from the rotational axis of the rotary member 2' within a limited range allowed by the elongated holes. Rotational imbalance caused by the impact member 11 is compensated by a balancing weight 13" mounted to the rotary member 2' at a position opposite the impact member 11 by means of a support pin 22. The casing 1 is provided with a holder 14' having a guide bore 15' for slidably receiving a reciprocative member 16' which has a shank 16a', a lower flange 16b' and a flat top surface 16c'. The holder 14' has a cylindrical cap portion 28 accommodating the flange 16b' of the reciprocative member 16' and fittable around a top portion of a pile 29. The cap portion 28 is internally provided with a stopper ring 30 which comes into abutment with the flange 16b' of the reciprocative member 16' to limit downward stroke thereof. The lower flange 16b' of the reciprocative member 16' serves to uniformly transmit impacts to the pile 29. As apparent from Figure 2, the guide bore 15' of the holder 14' or the shank 16a' of the reciprocative member 16' has a longitudinal axis L which extends perpendicularly to but deviates slightly from the rotational axis O of the rotary member 2'. Specifically, the longitudinal axis L deviates slightly from the rotational axis O in the direction opposite the rotational direction B of the rotary member 2'. Due to such an arrangement, only the top surface 16c' of the reciprocative member 16' in its upper limit position interferes with the rotating impact member 11, so that there is no need to provide a rounded head to prevent the impact member 11 from transversely hitting the shank 16a' of the reciprocative member 16'. In operation, the cap portion 28 of the holder 14' is fitted on the pile 29, so that the reciprocative member 16' is raised to its upper limit position. In this condition, the engine 23 is started to rotate the rotary member 2', whereby the impact member 11 centrifugally brought farthest from the rotational axis O of the rotary member 2' impinges on the flat top surface 16c' of the reciprocative member 16' every time the rotary member 2' makes one full rotation. Obviously, the pile 29 can be quickly driven into the ground by rotating the rotary member 2' at high speed. According to this embodiment, the flat top surface 16c' of the reciprocative member 16' comes into line contact with the cylindrical outer surface of the impact member 11. In this way, disadvantages (e.g. fatigue and local deformation) attendant with point contact can be avoided or reduced to prolong the life of the reciprocative member 16'. Further, the impact member 11 contacts the flat top surface 16c' of the reciprocative member 16' even after passage beyond the longitudinal axis L , thereby providing a longer contact period than if the reciprocative member 16' has a rounded head which allows contact only until the impact member reaches the longitudinal axis of the reciprocative member. This means that the pile 29 is driven into the ground to a greater degree upon each impact by the impact member 11. During impacting contact with the reciprocative member 16', the impact member 11 rolls on the flat top surface 16c' while gradually moving within the elongated holes 10a', 10b' toward the rotational axis O of the rotary member 2', thereby absorbing reaction shocks as well as preventing frictional heat production. The rotary impacting apparatus according to the invention may also be designed for shovelling, as illustrated in Figures 3 to 5. Referring to Figures 3 to 5, a casing 1 rotatably houses an elongated rotary member 2' which is drivingly connected to a small gasoline powered engine 23. More particularly, one shaft 3 of the rotary member 2' projects into a gear box 31 mounted to the casing 1. The shaft 3 is rotatably supported by the gear box 31 by means of bearings 7, 32, and carries a bevel gear 33. A transmission shaft 34 extending perpendicularly to the shaft 3 of the rotary member 2' has an output end 34 projecting into the gear box 31. This output end 34a is rotatably supported by the gear box 31 by means of bearings 35, 36, and carries another bevel gear 37 in mesh with the bevel gear 33. The transmission shaft 34 is enclosed in a support tube 38 and has an input end (not shown) connected to the output shaft (not shown) of the engine 23 via a centrifugal clutch 39 (not shown in detail). The engine 23 may be manually supported by means of a handle 40 which comprises a pair of side arms 40a and an intermediate grip 40c. The speed of the engine 23 may be adjusted by operating a throttle lever 41. The rotary member 2' is similar to that illustrated in Figures 1 and 2, except that an intermediate portion 2c' joining a pair of side flanges 2a', 2b' is positioned diametrically opposite a columnar impact member 11 to serve also as a balancing weight. According to this embodiment, a reciprocative member 16" is in the form of a shovel or scoop including a shank 16a", a scoop portion 16b" and a rounded head 16c". The scoop 16" is reciprocatively supported by a holder 14. Further, the scoop shank 16a' has a longitudinal axis L deviating slightly from the rotational axis O of the rotary member 2' in a manner similar to the embodiment of Figures 1 and 2. When the rotary member 2' is driven by the engine 23 with the scoop 16" pressed against the ground, the scoop 16" is advanced into the ground for scooping a desired amount of earth. As appreciated from Figures 2 and 5, the reciprocative member may have either a flat top surface or a rounded head in case it has a longitudinal axis L deviating from the rotational axis O of the rotary member. However, when the reciprocative member has a longitudinal axis extending radially of the rotary member, it must have a rounded head to avoid unacceptable lateral impacts. According to the invention, only the impact member and the balancing weight (if required) need to have a certain mass to fulfil their intended functions. Other components of the impacting apparatus may be made of light materials such as resin or light alloy. The invention being thus described, it is obvious that the same may be varied in many ways. For instance, the reciprocative member may be designed to conduct stamping of loose grounds or uncured asphalt pavements, or trimming of hardened concrete bodies.

Claims: A rotary impacting apparatus comprising: a casing (1); a rotary member (2') drivingly rotated within said casing about a rotational axis (O) and provided with arresting means (10a', 10b') at a position spaced from said rotational axis, said rotary member comprising a spaced pair of side flanges (2a', 2b') joined by an intermediate portion (2c'); at least one impact member (11) held by said arresting means for rotation with said rotary member about said rotational axis, said impact member being circularly columnar and rotatable about its own axis, said arresting means allowing said impact member to move toward and away from said rotational axis; a reciprocative member (16', 16") supported to move toward and away from said rotational axis within a limited range, said reciprocative member having a contact surface (16c', 16c") which comes into contact with said impact member rotating about said rotational axis when said reciprocative member is positioned closest to said rotational axis; wherein said arresting means comprises a pair of identical holes (10a', 10b') formed in said side flanges and elongated toward said rotational axis for receiving both ends of said impact member, each of said holes having a width substantially corresponding to the diameter of each end of said impact member, said each hole having a first arcuate portion for limiting the movement of said impact member toward said rotational axis; characterized in that: (a) said impact member is a cylinder with a constant cross-section along its entire length; and (b) said each elongated hole, which is in the form of a slot, has a second arcuate portion for limiting the movement of said impact member away from said rotational axis, the width of said each elongated hole being substantially equal to the constant diameter of said cylindrical impact member for allowing a close sliding fit thereof. The apparatus according to claim 1, wherein said rotary member (2') is provided with balancing means (2c', 13") for achieving rotational balance of said rotary member. The apparatus according to claim 2, wherein said balancing means comprises a balancing weight (13") disposed diametrically opposite said impact member (11). The apparatus according to claim 2, wherein said side flanges (2a', 2b') is connected together solely by said intermediate portion (2c') which is disposed diametrically opposite said impact member (11) to serve also as said balancing means. The apparatus according to any one of claims 1 to 4, wherein each of said flanges (2a', 2b') is non-circular but symmetrical with respect to a diametrical line passing through said rotational axis (O).

Inventors: YAMADA SAKUJI, YAMADA, SAKUJI
Applicants: YAMADA JUKI KK, YAMADA JUKI CO., LTD.
Application year: 1988
Main classification: B25D15
IPC codes: B25D17, E02D7, B25D11, B25D15