US3741317A - Seal arrangement for an electro pneumatic rock drill - Google Patents

Seal arrangement for an electro pneumatic rock drill Download PDF

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Publication number
US3741317A
US3741317A US00142924A US3741317DA US3741317A US 3741317 A US3741317 A US 3741317A US 00142924 A US00142924 A US 00142924A US 3741317D A US3741317D A US 3741317DA US 3741317 A US3741317 A US 3741317A
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US
United States
Prior art keywords
bore
piston
percussion piston
rearward
cylinder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00142924A
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English (en)
Inventor
J Unterschweiger
P Schmuck
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Hilti AG
Original Assignee
Hilti AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hilti AG filed Critical Hilti AG
Application granted granted Critical
Publication of US3741317A publication Critical patent/US3741317A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
    • B25D17/06—Hammer pistons; Anvils ; Guide-sleeves for pistons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D2217/00—Details of, or accessories for, portable power-driven percussive tools
    • B25D2217/0057—Details related to cleaning or cooling the tool or workpiece
    • B25D2217/0065—Use of dust covers

Definitions

  • A, piston is reciprocably mounted in the rearward part and is spaced from the rearward end of a percussion piston which ex- [30] Forelgn Application Pnonty Data tends into the forward part of the bore.
  • the piston transmits its reciprocating movement through the medium of an air cushion to the percussion [52] U.S. Cl 173/109, 173/116, 173/117 iston which in turn drives a tool held in a holder adja- [51] Int. Cl.
  • a space is provided at the forward end UNITED STATES PATENTS of the percussion piston when it is in its rearward posis,1e1,242 12/1954 Etzkorn 173/116 tion, into which filtered air is drawn and expelled 3,056,390 10/1962 Nyholm 173/109 wardly through the tool holder when the percussion 3,269,466 8/1966 Mitchell 173/1 16 piston transmits its energy to the tool so that dust-laden 3,154,154 96 1731/116 air cannot enter into the bore within the rock drill. 3,305,031 2/1967 Bez et al;
  • the present invention is directed to an electropneumatic rock drill construction and, more particularly, it is concerned with means for sealing the interior of the rock drill so that it can be operated without any problems being caused by dust-laden air entering its interior.
  • the rock drill includes a percussion piston sealed within a bore so that it can be driven through the medium of an air cushion by a reciprocating piston spaced from the percussion piston. The energy transmitted to the percussion piston is, in turn, directed against a tool positioned within a holdeR, such as a rock drilling tool.
  • Rock drills of the type mentioned above are exposed to rock dust-laden air which can have a very deleteRious effect an the useful lifetime and the safe operation of the drill.
  • One of the articular problems experienced in such apparatus is the provision of a seal in the vicinity of the tool holder for preventing dust-laden air from entering through the holder into the interior of the drill.
  • Rock drills of this type are known in which the tool holder has a bore which opens directly into the bore through the cylinder in which the percussion piston is positioned.
  • the dust-laden air from about the drill is drawn into the tool holder and in turn into the interior of the drill.
  • foreign bodies adhering to the tool shank present an additional source of fouling for the pistons within the rock drill.
  • the primary object of the present invention is to provide a sealed percussion piston for a rock drill which avoids the above-listed disadvantages.
  • the sealed arrangement is afforded by providing an axially extending bore through acylinder within the rock drill with the bore having a larger diameter section in its rear part as compared to a smaller diameter section in its forward part.
  • a reciprocating piston is positioned within the rear part of the bore and is separated from the rear end of a percussion piston by an air space which provides an air cushion during the operation of the rock drill.
  • a piston shank is provided on the percussion piston which extends forwardly into the forward part of the bore and has a diameter similar to that of the forward part of the bore and a seal member is provided in the bore which seals the bore when the percussion piston is reciprocated within the cylinder.
  • the interior of the cylinder that is the rearward part of its bore is sealed off from the entry of any dust-laden air regardless of the position of the percussion piston within the bore. Further, the energy is transmitted from the reciprocating piston through the percussion piston to the tool at the forward end of the rock drill without any additional energy loss.
  • the seal is provided within the reduced diameter portion of the bore by means of an annular packing fixed in relationship to the cylinder which prevents the penetration of any foreign bodies from passing along the shank into the rearward part of the cylinder bore.
  • the seal provided about the percussion cylinder serves to maintain the air cushion within the rearward part of the bore between the rear end of the percussion piston and the adjacent face of the reciprocating piston.
  • the bore through the cylinder has a rearward section with a larger diameter than its forward section.
  • the head of the percussion piston is guided within the rearward section of the bore while its shank extending toward the forward end of the drill extends through the forward section of the bore so that the percussion piston is guided in both sections of the bore and especially good sliding properties are provided.
  • Another characteristic of the invention is the arrangement of the rock drill housing adjacent the impact zone between the percussion piston and the tool within the tool holder. Apertures are provided through the housing in communication with the impact zone so that, due to the suction effected by the return stroke of the percussion piston, external air is drawn into the impact zone. Valves are provided in the path of the external air which close the passage into the impact zone during the forward or drive stroke of the percussion piston. As a result, a positive pressure relative to the atmosphere about the rock drill is provided and the external air drawn into the impact zone is expelled during the forward stroke of the percussion piston and directs the air through the clearance between the tool shank and the tool holder toward the forward end of the rock drill. Due to the positive displacement of the air from the impact zone outwardly any passage or rock dustladen air into the impact zone is prevented. Furthermore, the passage of air from the impact zone avoids any excessive heating of the impact transmission surfaces which would be disadvantageous to the operation of the drill.
  • filters are located in the path of the air being drawn into the impact zone so that any deleterious material can be removed.
  • FIG. 1 is a side view, partly in section, through a rock drill or similar device incorporating a percussion piston, in accordance with the present invention
  • FIG. 2 is an enlarged detail of a portion of the rock drill shown in FIG. 1;
  • FIG. 3 is another detail of a portion of the rock drill shown in FIG. 1 with the percussion piston in a different position.
  • FIG. 1 a rock drill or drill hammer is illustrated and is formed of a motor 1 secured to a drill housing 1A through the medium of a gear box 2. Further, a bandle 3 including a pressure switch 4 is secured to the motor and to the rearward end of the housing 1A.
  • a pinion 1a By means of a pinion 1a, the rotary movement of the motor is transmitted through a gear 5 to crank shaft 7 supported at its upper end within a bearing 6. Above the gear 5, teeth 7a are provided on the crank shaft 7 which intermesh with another gear 8 located within the gear box 2.
  • Gear 8 is mounted on a tapered pinion shaft supported within a bearing 9 at its upper end and is supported at its lower end on the upper part 1b of the motor housing.
  • the upper end of the pinion shaft 10 contains a bevel gear 11 which is interconnected with a matching bevel gear 12.
  • the rotary movement from the motor is transmitted through the pinion shaft 10 and its bevel gear 11 to the matching bevel gear 12 which, in turn, rotates a cylinder rotatably mounted within the housing 1A by bearings 13 and 14.
  • a bore 15b Extending axially through the rotatable cylinder 15 is a bore 15b having a rearward section 15b which has a larger diameter than its forward section 1512'.
  • a connecting rod 17 Secured to the upper end of the rotating crank shaft 7 by a crank pin 7b, is a connecting rod 17 which extends forwardly into the rearward section 15b of the cylinder bore.
  • the connecting rod 17 At its opposite end from the crank shaft 7, the connecting rod 17 is secured to a piston 16 which it reciprocates within the rearward section of the bore.
  • a percussion piston 18 Within the bore 15b of the cylinder 15 and spaced forwardly of the piston 16, is a percussion piston 18 which is separated from the forward end of the piston 16 by means of an air cushion within the space 19.
  • the percussion piston 18 is similarly moved back and forth through the bore in the cylinder through the medium of the air cushion in the space 19 which separates the two pistons.
  • the percussion piston 18 has a piston head 18a at its rearward end located within the rearward section 15b of the bore and a shank 18b extends forwardly from the piston head through the forward section 15b" to the forward end of the cylinder 15.
  • the kinetic energy of the percussion piston 18 is transmitted through the forward end of its shank 18b to the end of a tool 20 supported by its shank 21 within a tool holder22.
  • annular seal member 15a is secured in a stationary position within the cylinder so that it effects a seal against the sliding surface of the shank 18b of the percussion piston 18.
  • the shank 21 of the tool 20 is retained in the tool holder 22 by retaining members 23 which engage within axially extending grooves 21a in the surface of the shank 21.
  • a sleeve 24 surrounds a portion of the tool holder 22 and by rotating the sleeve in a known manner the members 23 can be displaced from engagement with the grooves 21a in the shank 21 and the tool can be removed from its holder.
  • the tool holder is secured to the forward end of the rotating cylinder 15 by means of a cap nut 25 which fits over the end of the tool holder and has a thread 250 which engages a similar thread on the cylinder.
  • a radially extending tooth system 22a is provided on the rearward end of the holder which engages the cylinder 15.
  • the apertures 1511 are then located rearwardly of the piston'head 18a and communicate with the space 19 forming the air cushion between the piston 16 and the piston head 18a.
  • the space 19 opened through the apertures 15d the air cushion is no longer operative and the percussion piston 18 cannot be reciprocated within the cylinder until the percussion piston is returned rearwardly through the bore 15b by the tool shank 21 so that the apertures 15d no longer communicate with the space 19.
  • FIG. 2 the forward end of the cylinder 15 and the rearward end of the tool holder 22 are shown on an enlarged scale.
  • air is drawn through an annular gap 35 between the housing 1A and the cap nut 25, through a filter 36, into a channel 37 and then through a passage 15c in the forward end of the cylinder into an impact transmission zone 39 located at the forward end of the cylinder 15 between the shank 18b of the percussion piston and the shank 21 of the tool 20.
  • an elastic ring 38 is provided which forms a valve arrangement for the passage of air into the impact transmission zone 39.
  • a packing 31a seals the zone off from the interior of the housing 1A and the gear box 2.
  • the forward end of the impact transmission zone is sealed off by the bevel 21b on the rearward end of the tool shank 21 which rests against an abutment ring 40 located at the rearward end of the tool holder 22.
  • the tool shank is driven forwardly with the engagement between its bevel 21b and the abutment ring being broken so that the air contained within the impact transmission zone 39'flows forwardly through the annular space 34 between the shank 21 and the interior surface of tool holder 22.
  • the positive displacement of the air forwardly through the annular space 34 prevents any flow of dust-laden air into the zone 39 and any dirt or other matter positioned on the tool shank within the holder 22 is also blown out through the forward end of the drill.
  • the flow of air outwardly through the holder 22 provides a cooling effect on the tool shank 21.
  • An electro-pneumatic rock drill and the like comprising a housing, an axially elongated cylinder rotatably mounted within said housing, said cylinder having an axially extending bore therethrough which has a forward part and a rearward part, a piston positioned within the rearward part of the bore in said cylinder, means for reciprocating said piston within the rearward part of the bore, a percussion piston located within and being axially slidably displaceable through said bore and being positioned therein spaced relationship from said piston, said housing arranged to support a tool at the forward end of said bore to which the energy transmitted to said piston across the air space within said bore from said reciprocating piston is supplied, the forward part of said bore having a smaller diameter size than the rearward part, the rearward section of said percussion piston being located within and having a diameter similar to the diameter of the rearward part of said bore and the forward section of said percussion piston being located within and having a diameter similar to the diameter of the forward part of said bore, and seal means positioned within the forward
  • An electro-pneumatic rock drill as set forth in claim 1, characterized in that said means for positioning a tool for limiting its rearward movement comprises a tool holder having a bore therethrough, attachment means for securing said tool holder to said rotatable cylinder with its bore in axial alignment with the bore in said cylinder, and an abutment ring at the rearward end of said holder and extending radially inwardly in the bore therethrough for limiting the extent to which a tool can be displaced rearwardly toward said percussion piston mounted in said cylinder.
  • An electro-pneumatic rock drill as set forth in claim 1, characterized in that said means for admitting air includes an air filter disposed in said passage for the incoming air for removing dust and other deleterious matter.
  • said means for reciprocating said piston comprises a crank shaft driven by said motor, a connecting rod secured at one end to said crank shaft and at its other end to the rearward face of said piston within the rearward part of said bore for reciprocating said piston within said bore in spaced relationship to said percussion piston.
  • An electro-pneumatic rock drill as set forth in claim 1, characterized in that said means for sealing said space during the forward stroke of said compression piston comprises a resilient ring-shaped member located within said passage for the air entering the space at the forward end of said bore and being arranged so that it seals the passage when said percussion piston is driven forwardly through said cylinder.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Percussive Tools And Related Accessories (AREA)
  • Earth Drilling (AREA)
  • Drilling And Boring (AREA)
  • Actuator (AREA)
US00142924A 1970-05-15 1971-05-15 Seal arrangement for an electro pneumatic rock drill Expired - Lifetime US3741317A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2023913A DE2023913B2 (de) 1970-05-15 1970-05-15 Elektropneumatischer Bohrhammer

Publications (1)

Publication Number Publication Date
US3741317A true US3741317A (en) 1973-06-26

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ID=5771258

Family Applications (1)

Application Number Title Priority Date Filing Date
US00142924A Expired - Lifetime US3741317A (en) 1970-05-15 1971-05-15 Seal arrangement for an electro pneumatic rock drill

Country Status (11)

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US (1) US3741317A (enrdf_load_stackoverflow)
JP (1) JPS5346761B1 (enrdf_load_stackoverflow)
AT (1) AT317803B (enrdf_load_stackoverflow)
CA (1) CA950288A (enrdf_load_stackoverflow)
CH (1) CH525067A (enrdf_load_stackoverflow)
CS (1) CS158294B2 (enrdf_load_stackoverflow)
DE (1) DE2023913B2 (enrdf_load_stackoverflow)
FR (1) FR2091304A5 (enrdf_load_stackoverflow)
GB (1) GB1316908A (enrdf_load_stackoverflow)
SE (1) SE397651B (enrdf_load_stackoverflow)
ZA (1) ZA712380B (enrdf_load_stackoverflow)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3837409A (en) * 1973-02-26 1974-09-24 Skil Corp Rotary hammer power tool
US3874460A (en) * 1972-10-28 1975-04-01 Bosch Gmbh Robert Impact wrench
US3921729A (en) * 1971-11-25 1975-11-25 Hilti Ag Electropneumatic hammer
US4064949A (en) * 1975-09-12 1977-12-27 Hilti Aktiengesellschaft Electropneumatic hammer
US4284148A (en) * 1978-05-09 1981-08-18 Robert Bosch Gmbh Portable hammer drill with rotating tool
US4346767A (en) * 1980-06-11 1982-08-31 Kango Electric Hammers Limited Rotary impact drill
US4601351A (en) * 1982-09-22 1986-07-22 Institut Cerac S.A. Electrically driven hammer machine
US4864727A (en) * 1988-05-16 1989-09-12 George Chu Pneumatic tool holder
USD447032S1 (en) 2000-04-19 2001-08-28 Robert Bosch Gmbh Hammer drill
US6488195B2 (en) 1998-09-18 2002-12-03 Stanley Fastening Systems, L.P. Multi-stroke fastening device
US6641634B2 (en) * 2000-02-10 2003-11-04 Robert Bosch Gmbh Hand-held tool with dust extraction
US20040226731A1 (en) * 2002-02-08 2004-11-18 Heinz-Werner Faatz Drilling and/or hammering tool
US20060144603A1 (en) * 2004-12-23 2006-07-06 Klaus-Dieter Arich Power tool housing
US20060144602A1 (en) * 2004-12-23 2006-07-06 Klaus-Dieter Arich Power tool cooling
US20070261871A1 (en) * 2006-05-05 2007-11-15 Oliver Ohlendorf Hand-held power tool with a chuck for receiving a percussion working tool
US20120007748A1 (en) * 2008-07-25 2012-01-12 Sylvain Forgues Controlled electro-pneumatic power tools and interactive consumable
US20150343625A1 (en) * 2013-01-18 2015-12-03 Illinois Tool Works Inc. Electropneumatic gas fastening device
US10710172B2 (en) 2017-07-31 2020-07-14 Milwaukee Electric Tool Corporation Rotary power tool

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2432105A1 (de) * 1974-07-04 1976-01-22 Duss Maschf Schlag- oder drehschlaghammer
DE2550725C3 (de) * 1975-11-12 1981-11-12 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Bohrhammer
DE2605998C3 (de) * 1976-02-14 1981-12-24 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Bohrhammer mit in einem Zylinder untergebrachten Antriebs- und Schlagelementen
DE2639310A1 (de) * 1976-09-01 1978-03-02 Duss Maschf Aus werkzeug, adapter und werkzeug- kupplung bestehender baugruppensatz fuer einen schlag- oder drehschlaghammer
DE2654875A1 (de) * 1976-12-03 1978-06-08 Hausherr & Soehne Maschf Vorrichtung zum selbsttaetigen stillsetzen eines druckmittelbetriebenen schlaggeraetes
AT368801B (de) * 1980-12-19 1982-11-10 Ver Edelstahlwerke Ag Schlagendes, handgehaltenes druckluftwerkzeug
ZA908924B (en) * 1990-01-15 1991-08-28 Sulzer Ag A percussion device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1281541A (fr) * 1961-01-10 1962-01-12 Skil Corp Dispositif porte-outil pour outil rotatif-percuteur

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921729A (en) * 1971-11-25 1975-11-25 Hilti Ag Electropneumatic hammer
US3874460A (en) * 1972-10-28 1975-04-01 Bosch Gmbh Robert Impact wrench
US3837409A (en) * 1973-02-26 1974-09-24 Skil Corp Rotary hammer power tool
US4064949A (en) * 1975-09-12 1977-12-27 Hilti Aktiengesellschaft Electropneumatic hammer
US4284148A (en) * 1978-05-09 1981-08-18 Robert Bosch Gmbh Portable hammer drill with rotating tool
US4346767A (en) * 1980-06-11 1982-08-31 Kango Electric Hammers Limited Rotary impact drill
US4601351A (en) * 1982-09-22 1986-07-22 Institut Cerac S.A. Electrically driven hammer machine
US4864727A (en) * 1988-05-16 1989-09-12 George Chu Pneumatic tool holder
US6488195B2 (en) 1998-09-18 2002-12-03 Stanley Fastening Systems, L.P. Multi-stroke fastening device
US6641634B2 (en) * 2000-02-10 2003-11-04 Robert Bosch Gmbh Hand-held tool with dust extraction
USD447032S1 (en) 2000-04-19 2001-08-28 Robert Bosch Gmbh Hammer drill
US20040226731A1 (en) * 2002-02-08 2004-11-18 Heinz-Werner Faatz Drilling and/or hammering tool
US7308950B2 (en) 2002-02-08 2007-12-18 Black & Decker Inc. Drilling and/or hammering tool
US20060144603A1 (en) * 2004-12-23 2006-07-06 Klaus-Dieter Arich Power tool housing
US20060144602A1 (en) * 2004-12-23 2006-07-06 Klaus-Dieter Arich Power tool cooling
US7331408B2 (en) 2004-12-23 2008-02-19 Black & Decker Inc. Power tool housing
US7705497B2 (en) 2004-12-23 2010-04-27 Black & Decker Inc. Power tool cooling
US20070261871A1 (en) * 2006-05-05 2007-11-15 Oliver Ohlendorf Hand-held power tool with a chuck for receiving a percussion working tool
US8176997B2 (en) * 2006-05-05 2012-05-15 Hilti Aktiengesellschaft Hand-held power tool with a chuck for receiving a percussion working tool
US20120007748A1 (en) * 2008-07-25 2012-01-12 Sylvain Forgues Controlled electro-pneumatic power tools and interactive consumable
US9061392B2 (en) * 2008-07-25 2015-06-23 Sylvain Forgues Controlled electro-pneumatic power tools and interactive consumable
US20150343625A1 (en) * 2013-01-18 2015-12-03 Illinois Tool Works Inc. Electropneumatic gas fastening device
US10710172B2 (en) 2017-07-31 2020-07-14 Milwaukee Electric Tool Corporation Rotary power tool
US10828705B2 (en) 2017-07-31 2020-11-10 Milwaukee Electric Tool Corporation Rotary power tool
US11185932B2 (en) 2017-07-31 2021-11-30 Milwaukee Electric Tool Corporation Rotary power tool
US12121980B2 (en) 2017-07-31 2024-10-22 Milwaukee Electric Tool Corporation Rotary power tool

Also Published As

Publication number Publication date
CA950288A (en) 1974-07-02
GB1316908A (en) 1973-05-16
CS158294B2 (enrdf_load_stackoverflow) 1974-10-15
CH525067A (de) 1972-07-15
FR2091304A5 (enrdf_load_stackoverflow) 1972-01-14
JPS5346761B1 (enrdf_load_stackoverflow) 1978-12-16
ZA712380B (en) 1972-01-26
DE2023913A1 (de) 1971-11-25
DE2023913B2 (de) 1978-11-02
AT317803B (de) 1974-09-10
SE397651B (sv) 1977-11-14

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