Method of manufacturing hydraulic hammer using male and female gauges

Abstract

A method of manufacturing a hydraulic hammer using a male gauge and a female gauge is provided wherein the hammer comprises a body and a chuck housing that are connectable by cooperatively formed thread fittings. A cooperatively threaded male gauge and female gauge can be used to form the threads on the body and the chuck housing and to determine the rotational orientation of the body and the chuck housing relative to one another. One of the gauges can be used to measure distortion of the chuck housing caused by heat treatment subsequent to the formation of the thread fitting and thereby to determine the required subsequent machining of the chuck housing necessary to retain the appropriate relative rotational orientation when the chuck housing is connected to the body. The method can comprise the steps of making and appropriately marking the male gauge and the female gauge.

Claims

1. A method of manufacturing a hydraulic hammer using male and female gauges; the hammer comprising a chuck housing with a first threaded fitting and a body machined with a cooperatively formed second threaded fitting such that the chuck housing and the body are configured to be screwed together; the male and female gauges each having a thread that is formed to allow the gauges to be screwed together and each having at least one circumferential marking such that the gauges' relative rotational position can be determined when they are screwed together; the method comprising the steps of: machining the chuck housing with the first threaded fitting such that a first of the male and female gauges can be screwed therein; fully screwing the first gauge into the chuck housing and marking the chuck housing such that a rotational position of the first gauge relative to the chuck housing can be determined; removing the first gauge; hardening the chuck housing; determining the distortion of the chuck housing caused by the hardening by fully screwing the first gauge into the chuck housing and determining their relative rotational positions; machining the chuck housing on the basis of the determined distortion; and machining the body with the second threaded fitting such that a second of the male and female gauges can be screwed thereon.

2. The method of claim 1, further comprising the step of: providing features on the body in positions determined by the angular position of the second gauge when it is fully screwed on the body.

3. The method of claim 1, further comprising the step of: screwing the chuck housing and the body together using the first threaded fitting and the second threaded fitting.

4. The method of claim 1, wherein the first gauge is the male gauge and the second gauge is the female gauge.

5. The method of claim 1, wherein the first gauge is the female gauge and the second gauge is the male gauge.

6. The method of claim 1, wherein a predetermined offset is included when marking the chuck housing.

7. The method of claim 1, wherein the chuck housing is hardened by heat treatment and oil quenching.

8. The method of claim 1, wherein the chuck housing is machined by machining down a face of the housing at an outer end of the first threaded fitting.

9. The method of claim 1, further comprising the step of: providing at least one feature on the chuck housing in positions determined by the position of the first gauge when it is fully threaded therein.

10. The method of claim 9, wherein the gauges are heat treated by a nitriding heat treatment system after manufacture.

11. The method of claim 1, wherein the male and female gauges are formed of a heat treatable bar stock material.

12. The method of claim 11, wherein the male and female gauges are formed of EN19 steel or EN24 steel.

13. The method of claim 1, further comprising the step of manufacturing the male and female gauges.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention can be even more fully understood with the reference to the accompanying drawings which are intended to illustrate, not limit, the present invention.

(2) FIGS. 1A-1C are diagrams of a body formed according to the method of the present invention;

(3) FIGS. 2A-2B are diagrams of a chuck housing formed according to the method of the present invention;

(4) FIG. 3 is an axial cross-section through a female gauge used in the method of the present invention; and

(5) FIG. 4 is an axial cross-section through a male gauge used in the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) A body 2 of a hammer formed according to a method of the present invention is shown in FIGS. 1A-1C. The body 2 is substantially cylindrical and has a male threaded fitting 3 at a first end. The body 2 has various other structural features 4 formed thereon. These features 4 are formed at an appropriate rotational position relative to the threaded fitting 3. The specific function of the features 4 is not relevant to the present invention and will not be described further, although their function will be immediately apparent to the skilled person.

(7) A chuck housing 5 of a hammer according to the present invention is shown in FIGS. 2A-2B . The chuck housing 5 is also substantially cylindrical and has a female threaded fitting 6 at a first end. The chuck housing 5 has a drill hole 7 formed through a cylindrical sidewall. The drill hole 7 is formed at an appropriate rotational position relative to the threaded fitting 6.

(8) A female gauge 8 used in the method of the present invention is shown in FIG. 3. The female gauge 8 is substantially cylindrical and has a female threaded fitting 9 at a first end. For reasons explained below, the female threaded fitting 9 of the female gauge 8 is substantially identical to the female threaded fitting 6 of the chuck housing 5 and fits with the male threaded fitting 3 of the body 2.

(9) A male gauge 10 used in the method of the present invention is shown in FIG. 4. The male gauge 10 is substantially cylindrical and has a male threaded fitting 11 at a first end. For reasons explained below, the male threaded fitting 11 of the male gauge 10 fits the female threaded fitting 9 of the female gauge and the female threaded fitting 6 of the chuck housing 5 and is substantially identical to the male threaded fitting 3 of the body 2.

(10) A hammer formed using the method of the present invention would also comprise further components including, but not limited to, a tool piece, a tool retainer, a lower cylinder liner, and a piston. The arrangement of these components with the chuck housing 5 and the body 2 will be immediately apparent to the person skilled in the art and, as such, they have not been illustrated in the Figures. It is considered that the skilled person would immediately understand what further components a hammer may comprise and their relation to the chuck housing 5 and body 2 shown in the Figures.

(11) In use, the body 2 is connected to the chuck housing 5 by means of the female threaded fitting 6 of the chuck housing and the male threaded fitting 3 of the body. The tool piece 12 is mounted in the chuck housing 5. The tool lower cylinder liner 14 is positioned within the chuck housing 5 and the body 2, around the tool piece 12 and the piston 15.

(12) The method of the present invention is used to manufacture the body 2 and the chuck housing 5 of the hammer in the following manner.

(13) Any pair of a male gauge 10 and a female gauge 8 may be used to make many identical hammers so it is not an essential step of the method of the present invention to make the male and female gauges. In the majority of instances of the use of the method of the present invention the person using the method will be able to utilise pre-existing and appropriate male and female gauges 10, 8 and will not be required to make the gauges.

(14) However, in some instances of the present invention it will be necessary for the person to machine new male and female gauges 10, 8. In such instances the first step of the method will be to machine a male gauge 10 and a female gauge 8 from a heat treatable bar stock material, such as EN19 or EN24 steel. The male and female gauges 10, 8 having a nominal bore size corresponding to the thread size required for the body 2 and the chuck housing 5. The male and female gauges 10, 8 are then screwed firmly together and a zero line (not shown) is marked across both gauges. The male gauge 10 is then marked at regular circumferential increments from the zero line, each marking corresponding to an angular distance from the zero line. The pitch of the threaded fittings 11, 9 will be known. Therefore, each marking will also correspond to an axial separation as the male gauge 10 is rotated apart from the female gauge 8. In particular, when a specific marking of the male gauge 10 is aligned with the zero mark of the female gauge 8 the male gauge will have been rotated apart from the female gauge 8 by the angular distance of that mark. This angular distance will be directly proportional to the corresponding axial separation of the male gauge 10 and the female gauge 8. The marks of the male gauge 10 may be scribed with this angular distance and/or the corresponding axial separation.

(15) After marking, each of the male gauge 10 and the female gauge 8 will be heat treated by a nitriding heat treatment system. This heat treatment causes little or no deformation of the male gauge 10 and the female gauge 8 and ensures that the accuracy of the zero marks and of the marks of the male gauge is retained.

(16) After making the male gauge 10 and the female gauge 8 or after selecting an appropriate pre-existing male gauge 10 and female gauge 8, the body 2 and the chuck housing 5 are made.

(17) The body 2 is machined with the male thread fitting 3. The male thread fitting 3 is machined to be a firm but easy screw fit with the female thread fitting 9 of the female gauge 8.

(18) The chuck housing 5 is machined with the female thread fitting 6. The female thread fitting 6 is machined to be a firm but easy screw fit with the male thread fitting 11 of the male gauge 10. The chuck housing 5 is initially formed such that it is slightly longer in axial length than is finally required. In particular it may be formed with a portion containing a female thread fitting 6 that extends axially outwards 0.1 mm further than is desired: such that if the 0.1 mm of additional chuck housing 5 at an outer end of the female thread fitting 6 were machined away the chuck housing would be of the desired length and the male gauge 10 would screw into the female thread fitting 6 such that when it is fully screwed in and in abutment with the chuck housing 5 it is in the preferred relative rotational alignment.

(19) The female gauge 8 is fully screwed onto the male thread fitting 3 of the body 2 and in this position a zero mark corresponding to the zero mark of the female gauge is marked on the body 2. The female gauge 8 may then be removed from the body 2. The features 4 of the body 2 are then machined on the body in a position relative to the zero mark on the body.

(20) The male gauge 10 is fully screwed onto the female thread fitting 6 of the chuck housing 5 such that it is in abutment with the chuck housing. A zero mark is then marked on the chuck housing 5. This zero mark is positioned at a predetermined angular distance from the zero mark of the male gauge 10. This angular distance is dependent on the additional axial length of the chuck housing 5. In particular, the angular distance directly corresponds to the additional axial length and is the angular distance by which the male gauge 10 could be further screwed into the chuck housing 5 were the additional axial length not present. The angular distance can be easily able to be calculated form the pitch of the thread and the additional axial length.

(21) The male gauge 10 is then removed from the chuck housing 5. The chuck housing 5 is then hardened by heat treatment and oil quenching. This hardening alters the chuck housing 5 dimensionally, such that if the chuck housing 5 and the body 2 were immediately screwed together there would be a significant further rotational misalignment between the zero marks thereof. As a result, it is necessary to machine the chuck housing 5.

(22) In order to do this, the male gauge 10 is again fully screwed onto the female thread fitting 6 of the chuck housing 5. In this position the zero mark of the chuck housing 5 is rotationally misaligned with the zero mark of the male gauge 10. The angular separation between the zero mark of the chuck housing 5 and the zero mark of the male gauge 10 will correspond to the axial length by which the chuck housing is required to be shortened in order to bring the zero marks back into alignment. Thus, the angular separation between the zero mark of the chuck housing 5 and the zero mark of the male gauge 10 is measured and thereby the length of axial length that is required is determined. The first end of the chuck housing 5 is then machined to reduce the axial length of the threaded fitting 11 by the determined amount. The amount removed includes the additional axial length with which the chuck housing 5 was initially formed.

(23) Finally, the chuck housing 5 and the body 2 may be screwed together in order to form a hammer and when this is done the zero mark of the housing and the body will be aligned. This ensures that all bodies 2 and chuck housings 5 of hammers made according to the method of the present invention can be interchanged and it is not necessary to replace both the body and the housing of a hammer if only one requires replacing.

(24) The present invention can include any combination of these various features or embodiments above and/or below as set-forth in sentences and/or paragraphs. Any combination of disclosed features herein is considered part of the present invention and no limitation is intended with respect to combinable features.

(25) The entire contents of all references cited in this disclosure are incorporated herein in their entireties, by reference. Further, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether such ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.

(26) Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the present specification and practice of the present invention disclosed herein. It is intended that the present specification and examples be considered as exemplary only with a true scope and spirit of the invention being indicated by the following claims and equivalents thereof.