Tie rod connection for a hydraulic hammer

A tie rod for use with a powered hammer assembly is provided that includes a body that defines a first end that is configured as a torque end, a second end that is configured as a fastening connecting end, and a longitudinal axis that extends from the first end to the second end, and a bearing surface that is positioned proximate the torque end along the longitudinal axis and that defines a tangent to the surface that forms an oblique angle with the longitudinal axis.

TECHNICAL FIELD

The present disclosure relates to hydraulic hammers such as those used by excavating machinery and the like. Specifically, the present disclosure relates to tie rods that hold the assemblies of hydraulic hammer units together using some sort of fastening connection.

BACKGROUND

Many conventional tie-rod designs for hydraulic hammers use a flat contact face requiring the machining of a sizable spot-face on the component being held. The precise flatness and perpendicularity of the spot-face of the spot face affects the integrity of the bolted joint. Angular misalignment of the tie rod may result if the spot face is not properly machined.

Conventional tie rod designs may be expensive to manufacture due to the much larger diameter of the torque end, and more particularly the flange. For example, a machined tie-rod requires a much larger diameter bar stock from which a large percentage of the material is removed attributing to higher cost. Also, the large spot face or flange requirement often show up as a difficult feature for 3D printing because the feature an over-hang requiring underlying support. The support material as well as the base must be removed after printing and in the case of metal parts, the support material must be machined away, adding cost.

U.S. Pat. No. 4,137,816 discloses an expansion dowel that is introduced into a borehole and that has a sleeve, an expanding body to be displaced into the sleeve for expanding it, a tie rod that is connected to the expanding body and an end support on the tie rod for applying torque to the dowel assembly. Torque is applied to the working surfaces on an end support of the dowel, that is, a bolt head or a nut, and the tie rod pulls the expanding body into the sleeve, spreading the sleeve into anchoring contact with the surface of the borehole. The expanding body may have a frusto-conically shaped surface that engages the sleeve and spreads the sleeve apart, creating a connection between the upper and lower ends of the expansion dowel. This connection relies solely on friction to maintain the holding power of the connection.

Accordingly, it is desirable to develop an improved tie bar connection for a hydraulic hammer and the like that is easier to manufacture and that provides a more robust connection than has been previously devised.

SUMMARY

A tie rod for use with a powered hammer assembly is provided that includes a body that defines a first end that is configured as a torque end, a second end that is configured as a fastening connecting end, and a longitudinal axis that extends from the first end to the second end, and a bearing surface that is positioned proximate the torque end along the longitudinal axis and that defines a tangent to the surface that forms an oblique angle with the longitudinal axis.

A powered hammer assembly is provided that includes a lower head that defines a plurality of tie rod bores, an upper head that defines a plurality of tie rod bores, wherein the bores of the lower head and the upper head define longitudinal axes. The assembly further includes a plurality of tie rods, wherein at least one tie rod comprises a torque end and a bearing surface positioned adjacent the torque end and the upper head defines at least one bearing surface that is partially complimentary shaped to the bearing surface of the tie rod for engagement therewith, wherein at least one of the bearing surfaces of either the upper head or the tie rod define a tangent to the surface that forms an oblique angle to the longitudinal axis of a bore. At least one of the bearing surfaces of the upper head or the tie rod may be axis-symmetrical about the longitudinal axis of a bore.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In some cases, a reference number will be indicated in this specification and the drawings will show the reference number followed by a letter for example,100a,100betc. It is to be understood that the use of letters immediately after a reference number indicates that these features are similarly shaped and have similar function as is often the case when geometry is mirrored about a plane of symmetry. For ease of explanation in this specification, letters will often not be included herein but may be shown in the drawings to indicate duplications of features discussed within this written specification.

While specific mention will be made to hydraulic hammer assemblies hereinafter, it is to be understood that any of the embodiments discussed herein may be used with any type of powered hammer assembly including those that are mechanically powered, electrically powered, etc.

Referring initially toFIG. 1, an excavating machine100of a type used for digging and removing rock and soil from a construction worksite is shown. The excavating machine100may incorporate a cab body102containing an operator station, an engine, and operating controls (not depicted). The machine100may be supported by, and may move on, tracks104. An extensible boom106may be movably anchored to the cab body102, and an articulating stick108, also sometimes called a lift arm, may be secured to and supported for movement on the boom106. The excavating machine100may incorporate a hydraulic hammer110as depicted, or may alternatively incorporate another implement, at an operational end112of the stick108. Hydraulic cylinder actuators114may be utilized to move the stick108relative to the boom106, and to move the hydraulic hammer110relative to the stick108.

Referring now also toFIG. 2, the hydraulic hammer assembly110may be secured to the operational end112of the stick108. The hydraulic hammer assembly110may include an upper portion116that includes a power cell118shown below inFIG. 3and a lower so-called front head portion122secured to the power cell118. A hammer tool120having an upper end (not shown) may be retained within the front head portion122. The hammer tool120may be adapted to produce cyclic vibrational movement at an intensity sufficient to demolish rocks, for example. The functional parts of the hydraulic hammer assembly110, including the hammer tool120may be constructed of a forged or otherwise hardened metal such as a refined steel, for example, to assure appropriate strength, although other suitable materials such as diamond bits for operative portions of the hammer tool120, for example, may be utilized within the scope of this disclosure.

Referring now also toFIG. 3, the hydraulic hammer assembly110is shown alone, i.e. detached from the stick108and with its exterior case covers removed, to reveal an exposed power cell118, and a plurality of tie rods124circumferentially disposed about a cylindrical piston-containing sleeve structure126. The sleeve structure126may contain a piston (not shown) adapted to drive the hammer tool120. As such, the power cell118may be effective to utilize a suitable working fluid, such as a hydraulic and/or pneumatic fluid, for example, to reciprocally impact the piston against the upper end (not shown) of the hammer tool120. It may also be appreciated that the plurality of tie rods124may be effective to retain or hold the power cell118and the front head portion122together under harsh impact loads as may be experienced within the hydraulic hammer assembly110.

The lower front head portion122may define an actual front head128, which may function as a structural housing to support the upper end (not shown) of the hammer tool120(shown only fragmentarily inFIG. 3). An upper end130of each of the tie rods124may be secured to an upper structure or upper head132of the power cell118. Each tie rod124may have a threaded lower end (not depicted) that extends downwardly through a vertically oriented aperture or tie rod bore134within the front head122. The tie rod bore134defines a longitudinal axis of the installed tie rod124. Each tie rod124may be adapted to be threadedly secured to a tie rod nut136.

Looking now atFIG. 4, an example of an improved tie rod connection for a hydraulic assembly400is illustrated. The hydraulic hammer assembly400comprises a lower head that defines a plurality of tie rod bores (not shown inFIG. 4but is to be understood to be present referring back toFIG. 3) and an upper head402that defines a plurality of tie rod bores404. Each of the bores of the lower head and the upper head define longitudinal axes406,418. A pair of bores, one each from the lower head and upper head402align such that their longitudinal axes406,418are coextensive. These bores are located on each corner of the upper head402and lower head. Only three such bores404are shown inFIG. 4, knowing that the fourth bore is present opposite the depiction of the bore404and associated tie rod408shown in the forefront. A power cell118that includes hydraulic mechanisms for moving the work tool up and down is located within the assembly400(not shown here but is to understood to be present referring back toFIG. 3).

A plurality of tie rods408are provided although only one is shown here inFIG. 4for the sake of simplicity. At least one tie rod408comprises a torque end410and a bearing surface414positioned adjacent the torque end410. The upper head402defines at least one bearing surface412that is at least partially complimentary shaped to the bearing surface414of the tie rod408for engagement therewith. As shown both bearing surfaces412,414are completely complimentary shaped to each other and define a tangent416that forms an oblique angle to the longitudinal axis406of the bore404and the longitudinal axis418of the tie rod408, which are essentially coextensive with each other for this embodiment. Because the surfaces412,414are conically shaped, their tangents416are coextensive with the surfaces412,414themselves. This may not be the case when other surfaces such as radial, spherical or other axis-symmetrical surfaces are used.

In some embodiments, at least one of the bearing surfaces412,414of either the upper head402or the tie rod408define a tangent416to the surface412,414that forms an oblique angle α to the longitudinal axis406of a bore and at least one of the bearing surfaces412,414of the upper head402or the tie rod408is axis-symmetrical about the longitudinal axis406of a bore404while the other may not. For example, the perimeter420of the bore404may have a square shape that is proximate angled surfaces that are tangent to the conical surface of the tie rod408or vice versa.

For this embodiment, both the bearing surfaces412,414of the upper head402and the tie rod408form an oblique angle α with the longitudinal axis of the bore404and are axis-symmetrical about the longitudinal axis406.

For the embodiment shown inFIG. 4, it is contemplated that every tie rod408is similarly configured and every bore404of the upper head402is positioned adjacent a bearing surface412that is complimentary shaped to engage the corresponding bearing surface414of the tie rod408. Specifically, the bearing surface412extends from the perimeter420of the bore404along the longitudinal axis406of the bore404.

The upper end of the tie rod408is configured to act as the torque end410and includes a standardized hexagonal shape that fits with a standardized wrench configuration. Other shapes such as allen wrench shapes, torx wrench shapes, etc. could also be used.

FIGS. 4 and 5show the tie rod408having a truncated length along the longitudinal axis418for the ease of illustration. It is to be understood that it could be much longer. The tie rod408further defines a second end422that is opposite the torque end410and a longitudinal axis418that extends between the torque end410and the second end422. The second end422may comprise a fastening connection422such as threads or a clip ring groove, etc. as desired. The tie rod408further comprises a shank portion428positioned between the torque end410and the second end422along the longitudinal axis418. As shown, the shank portion428is shorter than the threaded portion422along the longitudinal direction418, but in other embodiments, the shank portion428is longer than the second threaded end422along the longitudinal axis418.

Focusing now onFIGS. 4 and 5, two embodiments of a tie rod408of the present disclosure are disclosed. The tie rods408include a body409that defines a first end410that is configured as a torque end410, a second end422that is configured as a fastening connecting end422, and a longitudinal axis418that extends from the first end410to the second end422, and a bearing surface414that is positioned proximate the torque end410along the longitudinal axis418and that defines a tangent416to the surface that forms an oblique angle α with the longitudinal axis418. The angle α taken at a midpoint424of the bearing surface414along the longitudinal axis418is approximately 30 degrees. However, this may vary depending on the application.

The torque end410may comprise a faceted perimeter426. This may be defined by a protrusion as shown inFIGS. 4 and 5or a recess. The bearing surface414is positioned between the first end that is configured as a torque end410and the second end422that is configured as a fastening connecting end422along the longitudinal axis418. In some embodiments, the faceted surface426of the torque end410may be located lower than the bearing surface414such as in a recess.

InFIGS. 4 and 5, the bearing surface414is a conical and spherical surface respectively, and they are axis-symmetrical about the longitudinal axis418. A shank portion428is positioned between the first and second ends410,422along the longitudinal axis418. A flange portion430is positioned immediately between the torque end410and the bearing surface414along the longitudinal axis418. The bearing surface414defines a perimeter proximate the flange430and the flange430defines a side surface432that extends from the perimeter434of the bearing surface414along the longitudinal axis418. This spacial relationship may vary in other embodiments. The torque end410defines a polygonal perimeter426that is offset O from the side surface432of the flange430toward the longitudinal axis418.

INDUSTRIAL APPLICABILITY

In some embodiments of the present disclosure, using a conical, spherical, or other axis-symmetric shape for the torque end means that a flat spot-face is no longer required on the held component. Also, the conical seat reduces the cost of machining by reducing the diameter of the bar stock required. In still other embodiments, an improvement of the bolted joint is provided by eliminating lateral and angular misalignment as well as providing a better contact surface. Furthermore, a conical or spherical surface can also be designed to be self-supporting in a 3D print configuration, eliminating the need for building support structures and its subsequent removal.

For this embodiment, the bearing surface is made integral with the body of the tie rod itself, however, it is contemplated that the bearing surface could be incorporated into a separate nut member that surrounds the shaft of the tie rod in other embodiments. In embodiments where the tie rod has an integral flange for pushing down on the nut member that includes the bearing surface, the internal hole of the nut may lack any threads and may ride on a smooth portion of the shaft of the tie rod. In other embodiments, the internal hole of the nut member may be internally threaded for engaging external threads disposed on the shaft of the tie rod.

Using the embodiments of the apparatus as discussed, rotating the tie rod causes the threaded end to tighten on a nut, pulling the tie rod downward until its bearing surface contacts the bearing surface of the upper head. Since these surfaces are configured to provide a lead-in, proper alignment of the tie rod occurs and better contact is achieved.

It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the apparatus and methods of assembly as discussed herein without departing from the scope or spirit of the invention(s). Other embodiments of this disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the various embodiments disclosed herein. For example, some of the equipment may be constructed and function differently than what has been described herein and certain steps of any method may be omitted, performed in an order that is different than what has been specifically mentioned or in some cases performed simultaneously or in sub-steps. Furthermore, variations or modifications to certain aspects or features of various embodiments may be made to create further embodiments and features and aspects of various embodiments may be added to or substituted for other features or aspects of other embodiments in order to provide still further embodiments.

Accordingly, it is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention(s) being indicated by the following claims and their equivalents.