WO1993010964A1 - A method of making a seal - Google Patents

A method of making a seal Download PDF

Info

Publication number
WO1993010964A1
WO1993010964A1 PCT/GB1992/002168 GB9202168W WO9310964A1 WO 1993010964 A1 WO1993010964 A1 WO 1993010964A1 GB 9202168 W GB9202168 W GB 9202168W WO 9310964 A1 WO9310964 A1 WO 9310964A1
Authority
WO
WIPO (PCT)
Prior art keywords
groove
former
seal
face
longitudinal axis
Prior art date
Application number
PCT/GB1992/002168
Other languages
French (fr)
Inventor
David Henry Roberts
Original Assignee
Dowty Seals Limited
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 Dowty Seals Limited filed Critical Dowty Seals Limited
Publication of WO1993010964A1 publication Critical patent/WO1993010964A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D99/00—Subject matter not provided for in other groups of this subclass
    • B29D99/0053—Producing sealings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
    • B21H7/00—Making articles not provided for in the preceding groups, e.g. agricultural tools, dinner forks, knives, spoons
    • B21H7/18—Making articles not provided for in the preceding groups, e.g. agricultural tools, dinner forks, knives, spoons grooved pins; Rolling grooves, e.g. oil grooves, in articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
    • B26D3/00—Cutting work characterised by the nature of the cut made; Apparatus therefor
    • B26D3/08—Making a superficial cut in the surface of the work without removal of material, e.g. scoring, incising
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
    • B29C59/007—Forming single grooves or ribs, e.g. tear lines, weak spots
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
    • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
    • B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/44—Free-space packings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/26—Sealing devices, e.g. packaging for pistons or pipe joints

Definitions

  • This invention relates to a method of making a seal, in particular, a grooved seal.
  • Grooved seals are often used to form a seal about rotating shafts of machines.
  • the grooves give an hydrodynamic effect which drives lubricant away from the seal.
  • these grooves have been machined into the seal material using a sharp cutting tool.
  • the resultant grooves have had a coarse surface texture which retains a film of lubricant in the groove. Eventually, the retained oil burns onto the surface and the groove becomes choked and ineffective.
  • the cutting tool is blunted after cutting grooves in a modest number of elements. If a blunt tool is used to cut further grooves, tearing and chipping can occur in the seal material producing a poor quality groove leading to premature failure.
  • a ccordingly the invention provides a method of making a grooved seal comprising the steps of provi d ing a seal blank, providing a rotatably mounte d groove former, pressing the former and seal b lank into contact and causing relative mo t ion of the former and seal blank to form a g roove in t h e blank, the relative motion causing a rotational movement of the former.
  • the groove is formed by a crushing action in the ma t eria l as opposed to a cutting action.
  • the groove t exture is, as a result, smoother and tearing an d chipping is less likely to occur.
  • t h e groove former is a wheel rotatably mounted in a holder.
  • the groove former will comprise a hard material of a cross section matching that of the required groove and, preferably, will comprise a tungsten carbide metal alloy.
  • Figures 1 to 4 show a method of making a seal in accordance with the invention.
  • Figure 5 shows, in plan view, a seal groove forming tool in accordance with the invention.
  • the outside diameter and inside diameter of the rod has been formed in a previous lathing operation well known to those skilled in the art.
  • the lathe chuck 2 rotates the
  • a groove forming tool 4 is brought into contact with a planar annular end face 5 of the rod 1 and then pressed axially into the material. Progressively, the tool 4 is moved radially inwards, towards the axis 3 y from distance X to distance Y from the axis 3.
  • the pressure is gradually removed to form a helical groove centred on axis 3 with a gradual groove run out, that is to say, the depth of the groove gradually decreases as it approaches Y.
  • the tool 4 comprises a tungsten carbide rolling wheel 6 rotatably mounted about an axle 7 in a wheel holder 8.
  • the wheel 6 has a tapering edge 9 to form the desired cross- section of groove 10, as more clearly shown in Figure 3.
  • the seal is completed by a parting operation in which a cutting tool 11 is brought radially inwards, starting from a point the desired thickness Z of the finished seal from the end face 5, towards the axis 3 as shown in Figure 4.
  • a cutting tool 11 is brought radially inwards, starting from a point the desired thickness Z of the finished seal from the end face 5, towards the axis 3 as shown in Figure 4.
  • the cut end face of the remaining stock is machined flat and true and the previously described operations repeated.
  • a preferred form of seal groove forming tool is shown in Figure 5 and it comprises a holder 12 having a selectively rotatable carriage 13 mounted by a stud 14 at one end.
  • the carriage 13 is retained by the stud in a generally circular recess 15 in the holder 12.
  • Rotatably mounted in the carriage 13 are four tungsten carbide wheels 16, 17, 18 and 19. When wheel 16 has worn, the carriage 13 is rotated clockwise until unused wheel 17 is in position for use. Likewise, wheel 17 may be replaced by wheel 18 and wheel 18 by wheel 19.
  • a completed seal was placed in an air oven at 200°C for a period of 24 hours. Examination of the seal showed that material recovery had been minimal.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Agronomy & Crop Science (AREA)
  • Forests & Forestry (AREA)
  • Sealing Devices (AREA)
  • Sealing With Elastic Sealing Lips (AREA)

Abstract

A grooved seal is formed by pressing a groove former (6) into an end face (5) of a seal blank and causing relative motion between the blank and the former (6). The former (6) takes the form of a rotatably mounted wheel held in a holder (8) which is caused to rotate by the relative motion. The groove (10) is thus formed by a crushing action which imparts a fine surface texture on the groove (10).

Description

A METHOD OF MAKING A SEAL TECHNICAL FIELD
This invention relates to a method of making a seal, in particular, a grooved seal.
Grooved seals are often used to form a seal about rotating shafts of machines. The grooves give an hydrodynamic effect which drives lubricant away from the seal. In the past these grooves have been machined into the seal material using a sharp cutting tool. However, the resultant grooves have had a coarse surface texture which retains a film of lubricant in the groove. Eventually, the retained oil burns onto the surface and the groove becomes choked and ineffective.
For some glass filled seal materials, the cutting tool is blunted after cutting grooves in a modest number of elements. If a blunt tool is used to cut further grooves, tearing and chipping can occur in the seal material producing a poor quality groove leading to premature failure.
Even whilst the tool is sharp, burring can occur requiring a further operation to be carried out to remove the burs .
DISCLOSURE OF THE INVENTION
It is an object of the invention to provide a method for forming a groove in a seal with a finer surface texture.
Accordingly the invention provides a method of making a grooved seal comprising the steps of providing a seal blank, providing a rotatably mounted groove former, pressing the former and seal blank into contact and causing relative motion of the former and seal blank to form a groove in the blank, the relative motion causing a rotational movement of the former.
By using a rotatably mounted groove former, the groove is formed by a crushing action in the material as opposed to a cutting action. The groove texture is, as a result, smoother and tearing and chipping is less likely to occur.
Preferably, the groove former is a wheel rotatably mounted in a holder. The groove former will comprise a hard material of a cross section matching that of the required groove and, preferably, will comprise a tungsten carbide metal alloy.
DESCRIPTION OF THE DRAWINGS A specific embodiment of the invention will now be described, by way of example only, with reference to the drawing in which:
Figures 1 to 4 show a method of making a seal in accordance with the invention; and
Figure 5 shows, in plan view, a seal groove forming tool in accordance with the invention.
With reference to Figure 1, a cylindrical rod 1 formed of polytetrafluoroethylene. PTFE, filled with 5% glass and 5% MoS2 is removably mounted in a lathe chuck 2. The outside diameter and inside diameter of the rod has been formed in a previous lathing operation well known to those skilled in the art. The lathe chuck 2 rotates the
* cylindrical rod 1 about central longitudinal axis As the chuck 2 rotates, a groove forming tool 4 is brought into contact with a planar annular end face 5 of the rod 1 and then pressed axially into the material. Progressively, the tool 4 is moved radially inwards, towards the axis 3y from distance X to distance Y from the axis 3.
As the tool 4 approaches Y, the pressure is gradually removed to form a helical groove centred on axis 3 with a gradual groove run out, that is to say, the depth of the groove gradually decreases as it approaches Y.
As, shown in Figure 2, the tool 4 comprises a tungsten carbide rolling wheel 6 rotatably mounted about an axle 7 in a wheel holder 8. The wheel 6 has a tapering edge 9 to form the desired cross- section of groove 10, as more clearly shown in Figure 3.
The seal is completed by a parting operation in which a cutting tool 11 is brought radially inwards, starting from a point the desired thickness Z of the finished seal from the end face 5, towards the axis 3 as shown in Figure 4. To form the next seal the cut end face of the remaining stock is machined flat and true and the previously described operations repeated.
A preferred form of seal groove forming tool is shown in Figure 5 and it comprises a holder 12 having a selectively rotatable carriage 13 mounted by a stud 14 at one end. The carriage 13 is retained by the stud in a generally circular recess 15 in the holder 12. Rotatably mounted in the carriage 13 are four tungsten carbide wheels 16, 17, 18 and 19. When wheel 16 has worn, the carriage 13 is rotated clockwise until unused wheel 17 is in position for use. Likewise, wheel 17 may be replaced by wheel 18 and wheel 18 by wheel 19.
In a test of two seals 896-008-7280-00 formed according to the invention, the seals were used to seal a shaft running at 6,000 r.p.m. at 120°C. The lubricant used was B.P. UF7 which after 400 hours did not leak past the seal. No signs of burnt oil were found on the seals after completion of the test.
A further test was carried out to examine whether or not the groove would recover from the crushing action of the former.
A completed seal was placed in an air oven at 200°C for a period of 24 hours. Examination of the seal showed that material recovery had been minimal.

Claims

1. A method of making a grooved seal comprising bringing a groove former into contact with a face of a seal blank and causing relative motion between the former and face so as to form a groove in said face characterised in that the former (4) is rotatable mounted about an axis (7) so that said relative motion between the former (4) and face (5) causes the former (4) to rotate about said axis (7) .
2. A method as claimed in claim 1 further characterised in that the former (4) and seal blank (1) are rotated relative to one another about a longitudinal axis (3) and the former (4) contacts a face (5) of the blank (1) which extends laterally of said longitudinal axis (3) so as to form the groove (1) in said face (5) about said longitudinal axis (3) .
3. A method as claimed in claim 2 further characterised in that the former (4) is moved radially of said longitudinal axis (3) as it is moved relative to the face (5) so that the groove (1) takes the form of a spiral groove.
4. A method as claimed in claim 3 further characterised in that the depth of the groove (1) is varied by relative movement between the former (4) and face (5) in a direction parallel to said longitudinal axis (3) .
SUBSTITUTE SHEET
5. A method as claimed in any one of claims 2 to 4 further characterised in that the seal blank (1) is rotated abour. said longitudinal axis (3)
6. Amethod as claimed in any one of claims 2 to 5 further characterised in that the end of the seal blank (1) formed with the groove (10) is severed from the seal blank (1) to produce said seal and leave a fresh face (5) for the formation of the groove (10) for the next seal.
7. A method as claimed in any one of the preceding claims further characterised in that the groove former (4) comprises a wheel (6) rotatably supported in a holder (8) about said axis (7) and formed with a radial peripheral profile to match the cross-section of the groove (10).
PCT/GB1992/002168 1991-11-29 1992-11-24 A method of making a seal WO1993010964A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9125477.1 1991-11-29
GB9125477A GB2261920B (en) 1991-11-29 1991-11-29 A method of making a seal

Publications (1)

Publication Number Publication Date
WO1993010964A1 true WO1993010964A1 (en) 1993-06-10

Family

ID=10705481

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1992/002168 WO1993010964A1 (en) 1991-11-29 1992-11-24 A method of making a seal

Country Status (3)

Country Link
CN (1) CN1073386A (en)
GB (1) GB2261920B (en)
WO (1) WO1993010964A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6705617B2 (en) * 2001-11-28 2004-03-16 Federal-Mogul World Wide, Inc. Hydrodynamic seal and method of making the same
DE202005006553U1 (en) 2005-04-22 2005-07-14 Vr Dichtungen Gmbh Radial shaft seal comprises membrane and support ring with centering section on its outer rim which press-fits into seal mounting and has wedge-shaped support section on its inner rim

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1988738A (en) * 1931-05-25 1935-01-22 Charles E Johnson Process of making piston rings
FR1421558A (en) * 1964-11-05 1965-12-17 New process for modifying the outer shape of a plastic object and the internal tensions in this object
US3735615A (en) * 1970-05-19 1973-05-29 J Shneider Method of making grooves on surface of articles and device for its realization
DE2304854A1 (en) * 1973-02-01 1974-08-22 Hoff Walter Profiled elongated plastic work-piece - by stress-free deformation of prefabricated work-piece, e.g. extrudate, having its basic shape
US3857156A (en) * 1973-12-19 1974-12-31 Federal Mogul Corp Method of making tetrafluoroethylene sealing elements with hydrodynamic action
DE2421936A1 (en) * 1974-05-07 1975-11-20 Speidel Kunststoffwerk Kg Joining glass fibre-reinforced shell parts - obtd. by making tongue-and- groove combination in shell edges, and glueing
US4385429A (en) * 1979-07-18 1983-05-31 Dynetics, Inc. Method of manufacturing a clutch plate
US4450614A (en) * 1982-02-19 1984-05-29 Microdot Inc. Method of making a polytetrafluoroethylene hydrodynamic seal
US5048382A (en) * 1989-08-23 1991-09-17 Mar Don Corporation Method for making elastomeric sealing device

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3939551A (en) * 1975-02-04 1976-02-24 Federal-Mogul Corporation Method of making polytetrafluoroethylene sealing elements with hydrodynamic action
US4243235A (en) * 1979-07-02 1981-01-06 The Mather Company Composite polytetrafluoroethylene and elastomer lip seal
US4542573A (en) * 1984-09-28 1985-09-24 The Fluorocarbon Company Method of producing a hydrodynamic seal

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1988738A (en) * 1931-05-25 1935-01-22 Charles E Johnson Process of making piston rings
FR1421558A (en) * 1964-11-05 1965-12-17 New process for modifying the outer shape of a plastic object and the internal tensions in this object
US3735615A (en) * 1970-05-19 1973-05-29 J Shneider Method of making grooves on surface of articles and device for its realization
DE2304854A1 (en) * 1973-02-01 1974-08-22 Hoff Walter Profiled elongated plastic work-piece - by stress-free deformation of prefabricated work-piece, e.g. extrudate, having its basic shape
US3857156A (en) * 1973-12-19 1974-12-31 Federal Mogul Corp Method of making tetrafluoroethylene sealing elements with hydrodynamic action
DE2421936A1 (en) * 1974-05-07 1975-11-20 Speidel Kunststoffwerk Kg Joining glass fibre-reinforced shell parts - obtd. by making tongue-and- groove combination in shell edges, and glueing
US4385429A (en) * 1979-07-18 1983-05-31 Dynetics, Inc. Method of manufacturing a clutch plate
US4450614A (en) * 1982-02-19 1984-05-29 Microdot Inc. Method of making a polytetrafluoroethylene hydrodynamic seal
US5048382A (en) * 1989-08-23 1991-09-17 Mar Don Corporation Method for making elastomeric sealing device

Also Published As

Publication number Publication date
GB2261920B (en) 1995-04-26
GB2261920A (en) 1993-06-02
GB9125477D0 (en) 1992-01-29
CN1073386A (en) 1993-06-23

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