US3774348A - Horizontal double disc grinder with anti-vacuum control - Google Patents

Horizontal double disc grinder with anti-vacuum control Download PDF

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Publication number
US3774348A
US3774348A US00138871A US3774348DA US3774348A US 3774348 A US3774348 A US 3774348A US 00138871 A US00138871 A US 00138871A US 3774348D A US3774348D A US 3774348DA US 3774348 A US3774348 A US 3774348A
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United States
Prior art keywords
discs
air
abrasive discs
abrasive
grinding
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Expired - Lifetime
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US00138871A
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English (en)
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E Dunn
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Litton Industries Inc
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Litton Industries Inc
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B55/00—Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition
    • B24B55/02—Equipment for cooling the grinding surfaces, e.g. devices for feeding coolant

Definitions

  • a double disc abrading machine such as a double disc grinder, which is particularly adapted for grinding opposite surfaces of thin workpieces (W), includes the injection of a metered amount of air into the coolant supplied through the spindles (13L and 13R) to eliminate a partial vacuum formed between the abrasive discs (14L and 14R). It is believed that hydrodynamic forces create a partial vacuum between the closely spaced abrasive discs (14L and 14R) which are rotated in the same or opposite directions. There may also be cohesive and/0r adhesive forces acting to draw the abrasive discs (14L and 14R) too close together.
  • This invention relates in general to new and useful improvements in double disc grinders, and more particularly, to a double disc grinder which is particularly adapted for grinding the opposite surface portions of extremely thin workpieces.
  • a metered supply of air is directed into the coolant volume during the grinding operation to eliminate the hydrodynamic forces which create a partial vacuum which interferes with the controlled movement of the disc supporting heads.
  • a double disc abrading machine for abrading the parallel sides of a thin workpiece to a precise dimension.
  • the machine includes a pair of abrasive discs, which are supported and rotated by respective spindles. Facilities are provided to advance and retract the discs, and for supporting the workpiece. Coolant is supplied through at least one of the spindles to the area between the discs. In order to eliminate the partial vacuum that forms between the discs, a volume of air is directed into one of the spindles during the abrading operation.
  • the air which is injected during the abrading operation is metered.
  • Furanism due to the assisting effect of normal atmospheric forces acting on the exterior of the abrasive discs.
  • the tooling arm or work holder maybe damaged when the abrasive discs are not retracted in unison, due to the vacuum or suction between the discs.
  • the work holder is susceptive to damage because of its thin size and the fact that the clearance between the work holder and the surface of the abrasive discs must be kept to a minimum to provide adequate support for the workpiece. This latter problem has been previously solved by the inventor through the injection of a quantity of air into the coolant system after the grinding cycle was finished, but before the abrasive discs were retracted.
  • a primary object of the instant invention is to provide a pneumatic system of metered air for reducing or eliminating a partial vacuum formed between narrowly spaced abrasive discs to enable specific workpiece size tolerances to be maintained.
  • Another object is to prolong the life of a thin tooling member which houses a workpiece in the grinding station, by avoiding overheating and buckling.
  • Another object is to prevent either of the grinding heads from drifting inwardly in response to the cohesive and adhesive forces of the coolant which forms a vacuum'between the abrasive discs, which later resists retraction of the abrasive discs.
  • FIG. 1 is a plan view of a horizontal double disc grinding machine embodying the principles of the invention, showing the workpiece, workpiece fixture, grinding discs, and other supporting structure;
  • FIG. 2 is a diagrammatic pneumatic and coolant circuit showing means for eliminating the hydrodynamic forces which create a vacuum-like phenomenon
  • FIG. 3 is a wiring diagram showing the control circuit for operating the retraction of the grinding heads in unison.
  • FIG. 4 is a diagrammatic schedule of the contact and status of the sparkout control device 4TR of FIG. 3.
  • FIG. 1 there is illustrated a longitudinal feed mechanism L and 10R, which advances an opposing pair of grinding heads 11L and 11R toward a thin workpiece W. EAch of the grinding heads 1 1L and 11R is slidably mounted on a machine bed 12.
  • the grinding heads 11L and 11R include spindles 13L and 13R, which carry abrasive discs 14L and 14R.
  • the abrasive discs 14L and 14R are driven through suitable connections by motors 161. and 16R.
  • the means for advancing the abrasive discs 14L and 14R toward one another consists of feed crews 17L and 17R mounted in the bed 12.
  • the feed screws 17L and 17R are in operative engagement with feed nuts 18L and 18R, which are mounted in bed 12, and in alignment with the grinding heads 11L and 11R respectively.
  • the workpiece W is held by a gun-type work carrier assembly 23 which is the subject of applicants U. S. Pat. No. 3,503,155, issued Mar. 31, 1970, which is expressly incorporated herein.
  • the work carrier assembly 23 is secured to the bed 12 and includes a work fixture or carrier 24 having an opening 26, which retains the workpiece W in an accurate position within the carrier 24.
  • the carrier 24 advances the workpiece W between the abrasive discs 14L and 14R by means of a fluid motor or cylinder 27.
  • the cylinder 27 is mounted on top of a track unit 28 and includes a piston rod 29 which is secured to the carrier 24. Movement of the piston rod 29 advances and retracts the carrier 24 and the workpiece W into the grinding position 30, as shown in FIG. 2, and the abrasive discs 14L and 14R are advanced in unison.
  • the carrier 24 is reciprocated during the grinding operation by movement of the piston rod 29 to effect the desired finish of the workpiece W and to promote uniform disc wear in a conventional manner.
  • the desired amount of liquid coolant from a supply source is delivered to the hollow spindles 13L and 13R by lines 31 and 32, respectively, for grinding purposes only. Also, coolant is supplied through a line 33 which is directed into the fixed hood 34, surrounding the abrasive discs 14L and 14R, for flushing swarf out of the hood.
  • the volume of coolant directed through the hollow spindles 13L and 13R to the workpiece W must be sufficient to provide a cooling effect during the grinding operation and to remove metal and abrasive particles. When grinding thin workpieces W, too little coolant permits overheating and distortion of the workpiece W, and too much coolant results in hydrodynamicdisturbance of the thin workholding or guiding tooling, such as the carrier 24.
  • each of the abrasive discs 14L and 14R be retracted in unison at completion of the grinding cycle after the parallel sides of thin workpieces W have been ground, in order to maintain size, and because of the minimum clearance which exists between the sides of the carrier 24 and the cutting surfaces of the abrasive discs 14L and 14R;
  • the width of the carrier 24 mustbe just slightly less than the width of the finish ground dimension of the workpiece W, because the carrier 24 remains between the cutting surfaces of the abrasive discs 14L and 14R during the entire grinding operation, as shown in FIG. 2.
  • the carrier 24 remains between the cutting surfaces of the abrasive discs 14L and 14R during the entire grinding operation, as shown in FIG. 2.
  • width of the carrier 24 may be 0.048 of an inch when a workpiece W. to be ground has a finished dimension of 0.054 of an inch. This provides a clearance of 0.003 of an inch between each side of the carrier 24 and the respective abrasive discs 14L and 14R. Also, the height of the carrier 24 is sufficient to withstand the torque which is applied through the workpiece W by each of the abrasive discs 14L and 14R, and to resist sidewise deflection, as much as is possible.
  • Deflection occurs when the hydrodynamic coolant pressure upon one side of the carrier 24 exceeds the corresponding pressure on the opposite side.
  • the carrier 24 may then be deflected to contact one of the respective abrasive discs 14L or 14R, and overheating, buckling, and ultimate destruction may result.
  • the carrier 24 can also be damaged if one of the abrasive discs 14L or 14R drifts inwardly, during completion of the grinding cycle. This can occur if the grinding heads 11L or 11R are urged toward each other, as the ambient air pressure against the rear side of the abrasive discs 14L or 14R acts upon them in the manner of huge pistons to cause inward movement.
  • the anti-vacuum control system shown in FIG. 2 includes a line 36 which is connected from a shop air supply 37 through a filter 43 to a line 46 having a metering valve 47 and a check valve 44.
  • the metering valve 47 provides a continuous metered amount of air to the spindle 13R through a connection 41 of a rotary union 42.
  • the check valve 44 prevents coolant from backflowing into the air control system.
  • a control valve 38 is mounted in a line 39 which is connected between the lines 36 and 46. The valve 38 is used to supply an additional, unmetered amount of air to the spindle 13R before retraction at the completion of a grinding operation in order to facilitate the separation of the abrasive discs 14L and 14R.
  • the anti-vacuum system operates to inject a metered supply of air through the valve 47 throughout the entire grinding oepration to reduce or eliminate the partial vacuum formed in the area between the abrasive discs 14L and 14R. This is particularly important during the final portion of a grinding cycle, known as the sparkout" or dwell interval, when the abrasive discs 14L and 14R are neither being advanced nor retracted by the feed mechanism L and 10R.
  • the partial vacuum which normally occurs between the closely spaced abrasive discs 14L and 14R is thus prevented from forming as the metered inflow of air remains continuous whenever coolant is being directed through the lines 31 and 32 to the spindles 13L and 13R.
  • Inward movement of the abrasive discs 14L and 14R can then be more precisely controlled by the feed mechanisms 10L and 10R, and the abrasive discs 14L and 14R are more precisely advanced and stopped in unison without the undesirableforces resulting from the vacuum which interferes with such movement at completion of the sparkout operation positions.
  • both of the abrasive discs 14L and 14R be retracted immediately and simultaneously at the conclusion of the sparkout operation. Therefore, just prior to the moment of retraction, the additional unmetered volume of air is injected into the fluid body between the abrasive discs 14L and 14R through the valve 38 which is at that moment, shifted to the right (FIG. 2) for a brief time interval.
  • the sum effect of the two systems of air injection occurring during this interval prevents less-thanambient pressure frornbieng generated between the closely spaced discs 14L and 14R by the sudden separation of the discs.
  • the injected air appears to reduce the tenacious quality of the fluid coolant body in rotative circulation between the discs 14L and 14R.
  • Coolant is being directed from a supply source to the hollow spindles 13L and 13R through the lines 31 and 32 respectively, in a conventional manner, as shown in FIG. 2.
  • Check valves 48 and 49 are provided in lines 31 and 32 respectively to'prevent backflow of coolant.
  • a constant volume of air is directed into the spindle 13R through the valve 47 in the line 46 to prevent the grinding heads 11L and 11R from drifting inwardly.
  • An unground workpiece W is placed into the opening 26 of the work carrier 24 and a -cycle startpushbutton IPB (FIG. 3)- is depressed.
  • a circuit is completed through a -cycle stoppushbutton 2PB and a normally closed contact 4TR3, to energize a -cycle startrelay SCR,
  • a sparkout clutch 4TR is energized which closed a contact 4TR1, and a -carrier advancerelay 6CR is energized through a limit switch contact lLSB which is normally closed.
  • the energization of the relay SCR closes a contact 5CR'1 which provides a holding circuit around the pushbutton IPB, after its release, to maintain energization of the relay SCR, the sparkout clutch 4TR, and the relay 6CR.
  • a contact 6CR1 is closed which energizes a solenoid SOL C and the piston rod 29 advances the work carrier 24 and the workpiece W into the grinding position 30.
  • a limit switch contact lLSA is closed which energizes a -carrier in limitrelay 4CR when the workpiece W is in its innermost position 30 and opens the limit switch contact lLSB which deenergizes the 'relay 6CR.
  • a contact 4CR1 is closed to complete a cir- 6CR1 opens to deenergize the solenoid SOL C and the piston rod 29 retracts the work carrier 24.
  • the work carrier 24 and the workpiece W are reciprocated within a predetermined range as determined by reversal dogs (not shown) on the carrier 24 by actuation of the limit switch contacts lLSA and lLSB, of a limit switch lLS, and a limit switch 2LS, to provide an improved surface on the sides of the workpiece W during the grinding operation.
  • the abrasive discs 14L and 14R continue advancing toward each other while the work carrier 24 continues to reciprocate until the facecut infeed limit switches 3LS and 4LS are closed, and facecut infeed is terminated.
  • the closing of the limit switches 3LS and 4LS complete a circuit through the contact 4TR1 to energize a sparkout motor 4TR.
  • a sparkout motor 4TR Continued energization of the sparkout motor 4TR ultimately closes a timed contact 4TR4, which energizes an -air injectortimer relay 6TR, closing a -time delaycontact 6TR1 which energizes an -air injectorrelay 10CR.
  • a contact 10CRl is closed which energizes a solenoid SOL F, and the valve 38 (FIG. 2) is shifted to the right.
  • the timed contacts 4TR1, 4TR2 and 4TR3 are simultaneously opened when the timed contact 4TR4 is closed when the sparkout clutch 4TR times out, as shown in FIG. 4.
  • the opening of the contact 4TR1 deenergizes the sparkout motor 4TR.
  • the opening of the contact 4TR2 deenergizes the relay 7CR, and the contact 7CR1 opens to deenergize the solenoid SOL D, which reverses the hydraulic pressure status in the facecut feed mechanisms 10L andlOR.
  • the opening of the contact 4TR3 deenergizes the relay SCR.
  • the contact SCRl opens to deenergize the sparkout clutch 4TR and the relay 6CR which permits the sparkout clutch 4TR to reset.
  • the contact 6CR1 opens to deenergize the solenoid SOL C to efi'ect retraction of the work carrier 24 and the workpiece W from between the abrasive discs 14L and 14R, which are being retracted.
  • the abrasive discs 14L and 14R are retracted by the feed mechanisms 10L and 10R at a rapid rate.
  • the solenoid SOL F is deenergized when the timer relay contact 6TR1 opens, after a time delay following retraction of the abrasive discs 14L and 14R which are retracted in unison.
  • the valve 38 is then returned to its original position by spring pressure and the un-metered air supply is blocked until the above opera tion is repeated for the next workpiece W.
  • the air of supply line 37 could be connected directly to one of the abrasive discs 14L or 14R rather than into one of the coolant lines. Also, it is not essential that air be supplied during the entire grinding operation. It is important, however, that air be supplied at a point in time which is early enough to prevent grinding to an undersize.
  • a double disc grinding machine for abrading the parallel sides of a workpiece mounted on a workholder comprising a pair of abrasive discs each mounted on a rotatable spindle,
  • a double disc grinding machine according to claim 1, further comprising means for preventing the passage of liquid coolant from said delivering means to said air source.
  • a double disc grinding machine further comprising means for selectively introducing a volume of air into said directing means with sufficient force and suddenness at the conclusion of stock removal and prior to abrasive disc retraction to eliminate any vacuum existent between the abrasive discs.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)
US00138871A 1971-04-30 1971-04-30 Horizontal double disc grinder with anti-vacuum control Expired - Lifetime US3774348A (en)

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US13887171A 1971-04-30 1971-04-30

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US (1) US3774348A (enrdf_load_stackoverflow)
JP (1) JPS5148717B1 (enrdf_load_stackoverflow)
CA (1) CA950677A (enrdf_load_stackoverflow)
DE (1) DE2204621C3 (enrdf_load_stackoverflow)
GB (1) GB1375490A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4358912A (en) * 1980-05-27 1982-11-16 Watanabe Shigeru Grindstone clearance correcting device for spring grinding machine
US4685845A (en) * 1985-09-30 1987-08-11 James Emter Guide pad resurfacing apparatus
US5121572A (en) * 1990-11-06 1992-06-16 Timesavers, Inc. Opposed disc deburring system
US6089959A (en) * 1998-10-23 2000-07-18 System Seiko Co., Ltd. Polishing method and polishing apparatus
US6485357B1 (en) * 2000-08-30 2002-11-26 Divine Machinery Sales, Inc. Dual-feed single column double-disk grinding machine
US6726525B1 (en) * 1999-09-24 2004-04-27 Shin-Estu Handotai Co., Ltd. Method and device for grinding double sides of thin disk work
US20060019218A1 (en) * 2004-07-20 2006-01-26 Kuo Eric E Combined interproximal reduction (IPR) disc/measurement tool
US20070128985A1 (en) * 2005-12-06 2007-06-07 Fujikoshi Machinery Corp. Method of polishing work
CN115256114A (zh) * 2022-06-02 2022-11-01 苏州方升电子科技有限公司 一种双工位便于调整的塑胶圆盘滚边设备
US20230398613A1 (en) * 2022-06-14 2023-12-14 Kennametal Inc. Cutting tools and cutting apparatus having contrary rotating portions

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RU2198082C2 (ru) * 2001-02-12 2003-02-10 Пензенский технологический институт Станок для двухсторонней полировки дисков
RU2285604C1 (ru) * 2005-02-08 2006-10-20 Государственное образовательное учреждение высшего профессионального образования "Ульяновский государственный технический университет" Способ двустороннего шлифования тонкостенных заготовок
RU2278016C1 (ru) * 2005-02-08 2006-06-20 Государственное образовательное учреждение высшего профессионального образования "Ульяновский гоударственный технический университет" Способ двустороннего шлифования тонкостенных заготовок
RU2405665C2 (ru) * 2008-11-17 2010-12-10 Альберт Султанович Джибилов Способ двухсторонней обработки деталей
CN107309726B (zh) * 2017-08-14 2024-06-25 海盐孚邦机械有限公司 一种柱塞套生产用半自动端面磨平机
CN113927390B (zh) * 2021-12-16 2022-04-29 宁波明讯实业有限公司 一种新能源汽车电机芯轴去毛刺设备

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2089040A (en) * 1935-07-05 1937-08-03 Gardner Machine Co Grinding machine and method of grinding
US2560944A (en) * 1948-07-08 1951-07-17 Oliver Instr Company Cooling system and apparatus for abrasive wheels
US2658316A (en) * 1950-09-08 1953-11-10 Joseph R Davies Method and apparatus for cooling buffs and polishing wheels
US3063203A (en) * 1959-08-27 1962-11-13 Besly Welles Corp Grinder
US3503155A (en) * 1967-09-15 1970-03-31 Landis Tool Co Disc grinder loader and carrier assembly
US3653160A (en) * 1969-04-23 1972-04-04 Ind Micronics Inc Lapping machine and method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2089040A (en) * 1935-07-05 1937-08-03 Gardner Machine Co Grinding machine and method of grinding
US2560944A (en) * 1948-07-08 1951-07-17 Oliver Instr Company Cooling system and apparatus for abrasive wheels
US2658316A (en) * 1950-09-08 1953-11-10 Joseph R Davies Method and apparatus for cooling buffs and polishing wheels
US3063203A (en) * 1959-08-27 1962-11-13 Besly Welles Corp Grinder
US3503155A (en) * 1967-09-15 1970-03-31 Landis Tool Co Disc grinder loader and carrier assembly
US3653160A (en) * 1969-04-23 1972-04-04 Ind Micronics Inc Lapping machine and method

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4358912A (en) * 1980-05-27 1982-11-16 Watanabe Shigeru Grindstone clearance correcting device for spring grinding machine
US4685845A (en) * 1985-09-30 1987-08-11 James Emter Guide pad resurfacing apparatus
US5121572A (en) * 1990-11-06 1992-06-16 Timesavers, Inc. Opposed disc deburring system
US6089959A (en) * 1998-10-23 2000-07-18 System Seiko Co., Ltd. Polishing method and polishing apparatus
US6726525B1 (en) * 1999-09-24 2004-04-27 Shin-Estu Handotai Co., Ltd. Method and device for grinding double sides of thin disk work
US6485357B1 (en) * 2000-08-30 2002-11-26 Divine Machinery Sales, Inc. Dual-feed single column double-disk grinding machine
US20060019218A1 (en) * 2004-07-20 2006-01-26 Kuo Eric E Combined interproximal reduction (IPR) disc/measurement tool
US20070128985A1 (en) * 2005-12-06 2007-06-07 Fujikoshi Machinery Corp. Method of polishing work
US8025554B2 (en) * 2005-12-06 2011-09-27 Fujikoshi Machinery Corp. Method of polishing work
CN115256114A (zh) * 2022-06-02 2022-11-01 苏州方升电子科技有限公司 一种双工位便于调整的塑胶圆盘滚边设备
US20230398613A1 (en) * 2022-06-14 2023-12-14 Kennametal Inc. Cutting tools and cutting apparatus having contrary rotating portions

Also Published As

Publication number Publication date
DE2204621B2 (de) 1974-05-09
DE2204621A1 (de) 1972-11-16
CA950677A (en) 1974-07-09
GB1375490A (enrdf_load_stackoverflow) 1974-11-27
DE2204621C3 (de) 1974-12-05
JPS5148717B1 (enrdf_load_stackoverflow) 1976-12-22

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