Double-Disc Grinding Cell. Double disc grinding

03.05.2023 Golticage cell, disc, double, double-disc, grinding

US4462187A. Headsetting structure for double disc grinding machine. Google Patents

Publication number US4462187A US4462187A US06/322,987 US32298781A US4462187A US 4462187 A US4462187 A US 4462187A US 32298781 A US32298781 A US 32298781A US 4462187 A US4462187 A US 4462187A Authority US United States Prior art keywords trunnion machine frame axis supporting double disc Prior art date 1981-11-19 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 US06/322,987 Inventor Elman R. Dunn Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.) Western Atlas Inc Original Assignee Litton Industrial Products Inc 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.) 1981-11-19 Filing date 1981-11-19 Publication date 1984-07-31 1981-11-19 Application filed by Litton Industrial Products Inc filed Critical Litton Industrial Products Inc 1981-11-19 Priority to US06/322,987 priority Critical patent/US4462187A/en 1981-11-19 Assigned to LITTON INDUSTRIAL PRODUCTS, INC. reassignment LITTON INDUSTRIAL PRODUCTS, INC. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: DUNN, ELMAN R. 1982-09-02 Priority to US06/414,455 priority patent/US4476847A/en 1984-07-31 Application granted granted Critical 1984-07-31 Publication of US4462187A publication Critical patent/US4462187A/en 2001-11-19 Anticipated expiration legal-status Critical Status Expired. Lifetime legal-status Critical Current

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Classifications

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
B24B7/00 — Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
B24B7/10 — Single-purpose machines or devices
B24B7/16 — Single-purpose machines or devices for grinding end-faces, e.g. of gauges, rollers, nuts, piston rings
B24B7/17 — Single-purpose machines or devices for grinding end-faces, e.g. of gauges, rollers, nuts, piston rings for simultaneously grinding opposite and parallel end faces, e.g. double disc grinders

Abstract

A double disc grinding machine comprising a wheelhead assembly, a base for supporting the wheelhead assembly for axial displacement relative thereto, the base including a front wall having a front trunnion secured thereto and extending horizontally therefrom, and a rear wall having a rear trunnion secured thereto and extending horizontally therefrom in coaxial relation with the front trunnion, and a principal machine frame including front and rear walls, the machine frame rear wall supporting the rear trunnion for pivotal displacement about its axis and for limited pivotal displacement about a mutually perpendicular vertical axis and structure for horizontally displacing the rear supporting structure along the rear wall of the frame thereby angularly displacing the front trunnion, and the machine frame front wall supporting the front trunnion for pivotal displacement about its axis and for limited pivotal displacement about a mutually perpendicular vertical axis.

Description

Double disc grinding machines use two abrasive disc wheels to remove stock and meet tolerance requirements on two opposite and parallel sides of product components or workpieces.

In double disc grinding machines, the angular relationship between the abrasive disc wheels, which are components of opposing wheelhead assemblies, must be readily and conveniently changeable as required to produce optimum grinding performance. This procedure, which is generally referred to as headsetting (wheelhead setting), includes a vertical-plane (tilt) setting and a horizontal-plane (swivel setting, usually to the same degree with regard to each disc face.

It is exceedingly important that precise and secure headsetting adjusting means be available, and that the as-adjusted angular headsettings remain virtually constant during ensuring grinding operations upon product components.

U.S. Pat. No. 1,638,028, issured Aug. 9, 1927, discloses a double disc grinding machine having a sub-base which is pivotally mounted on a knee for relative movement about a vertical axis with the knee pivotally mounted on a base for relative movement about a horizontal axis. A wheelhead assembly is supported for axial displacement on suitable sub-base ways or guides. A double disc grinding machine having upper and lower base parts mounted together for relative movement about vertical and/or horizontal axes is disclosed in U.S. Pat. No. 2,424,448, issued on July 22, 1947.

In the double disc grinding machine disclosed in U.S. Pat. No. 3,348,341, issued on July 16, 1964, headsetting is achieved by changing the axis of the wheelhead spindle relative to its housing.

It is an object of the present invention to provide an improved headsetting arrangement for a double disc grinding machine.

Other objects of the present invention will become apparent from the following portion of the specification and from the accompanying drawings which illustrate, in accordance with the mandate of the patent statutes, a presently preferred embodiment incorporating the principles of the invention.

FIG. 1 is a one half front and one half rear elevational view of a double disc grinding machine made in accordance with the teachings of the present invention the other unshown halves are mirrored images of the shown halves;

FIG. 2 is a view taken along the lines 22 of FIG. 1 illustrating the front pivotal support for a wheelhead assembly of the double disc grinding machine illustrated in FIG. 1;

FIG. 3 is a view taken along the lines33 of FIG. 1 similar to that of FIG. 2, but illustrating the rear pivotal support for the wheelhead assembly;

FIG. 4 is a view taken along lines 44 of FIG. 3 showing the adjusting means for adjusting the horizontal-plane (swivel) headsetting component; and

FIG. 5 is a side elevational view of the tilt adjusting assembly for the double disc grinding machine.

A double disc grinding machine generally comprises opposing wheelhead assemblies 10, each including a spindle 11 rotatably mounted in an axially slidable housing 12 and driven, via belts 14, by a motor 16 secured to the slidable housing. An abrasive disc wheel 17 is secured to each spindle for effecting stock removal from one of the two opposite flat and parallel surfaces of a workpiece.

The wheelhead assemblies are each supported on ways established on a base member 18 for sliding axial displacement toward and away from the workpiece. Each base member includes opposing side walls 20 (one shown) which have secured thereto coaxial trunnions 22, 23 (FIGS. 2 and 3) which are pivotally supported by upwardly projecting front and back walls 25 of the main machine foundation or frame structure.

The trunnions 22, 23 are supported for limited pivotal movement in ball bearing supports 30, each of which includes a face-to-face mounted pair of ball bearings 32 separated by a cylindrical spacer element 34 having a width selected to locate the bearing load centers P coincident on the axis of rotation of the trunnion. This permits the rear trunnion bearing assembly to be deliberately displaced slightly radially with respect to the front trunnion assembly by shifting the rear pivotal support, FIGS. 3 and 4, longitudinally along the rear wall of the base without damaging either bearing. Both front and rear trunnions, and the base member 18 to which both trunnions are attached, accordingly will thus be pivotally displaced in a horizontal plane, thereby effecting a swivel adjustment, of the total wheelhead assembly 10.

When such an adjustment is performed, the true pivot point P about which the wheelhead assembly is being swivelled is the front trunnion bearing load-center which lies coincident with the axis of the front trunnion 23, FIG. 2, as controlled by the axial thickness of spacers 34.

The rear trunnion ball bearing support shown in FIG. 3 includes upper and lower horizontal 40, 42 surfaces and upwardly and downwardly extending flange portions 44, 46. The lower horizontal bearing support surface 42 slidingly engages with the lower 48 horizontal surface of back wall opening 50 of the machine frame.

The rear wall opening 50 (FIG. 4) extends beyond the bearing support and includes selectively inclined surfaces 54 at either end of this opening. The spherical heads 56 of opposed swivel adjustment screws threadedly secured in suitable bearing support bores 60 are forcefully adjusted against these inclined surfaces to establish a selected longitudinal location of the bearing support along the machine frame. The forceful engagement between the spherical heads 56 of the adjusting screws and inclined surfaces 54 produces a downward force through the rear bearing housing to effectively clamp surface 42 against surface 48 of the machine frame.

double-disc, grinding, cell, double, disc

The rear bearing support is fixedly secured to the rear wall of the machine frame by belleville spring washer preloaded screw assemblies 62. Such screws pass through openings 64 in the bearing support flanges 44 and 46 which are substantially larger than the screws body diameters, thereby permitting limited longitudinal adjustment of the bearing support within wall opening 50.

Since a clearance type of annular seal member 66 is provided between the trunnion shoulders 68, 70 and the bearing support, limited reorientation is possible.

The front trunnion bearing assembly, which is illustrated in FIG. 2, does not require swivel adjustment facility. A nut 71 threadedly secured to the threaded end of the front trunnion 23 fixedly axially clamps the front trunnion and the entire wheelhead assembly thereby at a fixed transverse location with respect to the machine frame. Suitable covers 72 axially clamp each pair of trunnion bearings outer races under heavy-preload status in each bearing housing to eliminate all internal looseness of the bearings elements.

To control the tilt of each stock removal assembly, a tilt control assembly (FIG. 5) including a cam element 80 secured to a transverse frame wall 81, a plate 82 secured to the bottom of the adjustable base member 18 which supports the slidable spindle housing, and an axially adjustable control rod 84 having a crowned barrel end with a full-length cam follower surface 86 is provided. The left hand end of control arm 84 is threaded and a pair of bolts 85 on either side of wall 25 secure the control arm 84 at a desired location. To shift the control arm 84 to the left, the right hand of the two nuts 85 is rotated to the right (loosened) and the left nut is tightened. As the control arm is shifted axially left to right or right to left, the cam 80, which is a plate member having an inclined surface 86, will raise or lower the right hand end portion of the control arm 86 which is in the form of a cylindrical element having a mating slot defined therein raising or lowering the base member. Adjustment may be maintained with a clamp screw 88 which has it opposing ends threadedly received by a right-hand threaded aperture 90 in the base member 18 and a left-hand threaded aperture 92 in a bar nut 94 which draws tightly upward against a spherical washer assembly 94A underneath a transverse member 94B of the machine frame. This effectively clamps the wheelhead assembly downward upon the machine frame structure, to insure metal-to-metal contact at all adjoining surfaces of the adjusting mechanism.

The front and back walls of the machine frame (FIG. 1) have an elongated bottom portion 95 and an upwardly extending tapered portion 96. A vertical opening 97 permits the feeding of workpieces into the grinding zone between the opposed abrasive discs.

The top portion 98 of the front and rear walls above the vertical openings 97 is integral with the upwardly extending portions of the front and back walls 25 and are further strengthened by securing thereto a heavy tensile bolster 99.

Double-Disc Grinding Cell

Hypro Inc., a value leader in machining, manufacturing, assembly of components and complex parts, has ordered a turnkey double disc grinding cell from C B Machinery. C B Machinery develops and builds grinding systems for manufacturers around the world; in this case, it will build a “Park Grind” double disc grinding cell for Hypro, Waterford, Wis.

The grinding cell is designed to grind the faces of brake backing plates, up to 25″ in diameter, for agricultural and off road equipment. This machine will be set up to grind ten different backing plate configurations and be flexible for any future program changes. The grinding cycle time for a finished part will be 180 seconds.

Double disc grinders remove an equal amount of material from both faces, simultaneously. This machine performs a “rotary plunge” grinding cycle. A single brake backing plate is introduced to the grinding wheels via a reciprocator, the carrier rotation will begin and the shuttle carriage will travel forward into the grind zone to a part’s unique end position at which point the grinding wheels plunge grind simultaneously through axis interpolation. There are several advantages for grinding in this manner. The part is floating and rotating while being ground producing the best possible parallelism and flatness. Alternatively, parts like these can be introduced and ground using a magnetic chucking system, which can only grind one side of a part at a time. That process would add to grinding cycle time and add to the cost per piece thus reducing the return on investment.

This grinding cycle was developed by C B Machinery engineers. In addition to the operating and investment cost savings, it allows 100 percent gauge feedback on every component ground. Size control is tightened, resulting in higher statistical capability.

backing

Flexible portion of a bandsaw blade. 2. Support material behind the cutting edge of a tool. 3. Base material for coated abrasives.

disc grinding

Operation in which the workpiece is placed against the side of a wheel rather than the wheel’s periphery. See grinding.

grinding

Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.

interpolation

Process of generating a sufficient number of positioning commands for the servomotors driving the machine tool so the path of the tool closely approximates the ideal path. See CNC, computer numerical control; NC, numerical control.

Double-Disc Grinding On The Move

The double-disc grinding process is consolidating its position in automotive applications but is moving into other industries. Double-disc grinders are now easier to operate, and they have added capabilities for control flexibility, precision process control, faster changeovers, and grinding of nontraditional materials.

Featured Content

Double-disc grinding has long had a home in the automotive industry, where dedicated operations can take full advantage of its high productivity rates. Today, a number of advances allow double-disc grinders to meet requirements for improved performance in these traditional applications, and they also are opening the way to productive use in new applications. Capabilities are now available for easier machine operation, control flexibility, statistical process control (SPC), faster changeovers and setup, and applications on an expanded range of materials, including ceramics and graphite.

Easier Operation

The level of technology to be found in the latest generation of double-disc grinders is consistent with other types of state-of-the-art machine tools. As with today’s machining centers and turning centers, the advanced nature of double-disc grinders is best reflected in control features. For example, the latest controls include a more user-friendly operator interface, a color monitor, and a movable pendant that can be positioned in front of the machine for setup and in back of the machine, when necessary, for convenience during machine operation.

Such improvements address the concerns of the automotive industry, in particular, where machine operators frequently find themselves running a lathe one day, and a grinder the next. Plant managers in that industry rarely have the luxury of sending their operators to a two-week training school before making the transition from one machine to another.

Control Flexibility

The same technology that enhances the appeal of double-disc grinders to managers in the automotive field also heightens its appeal to users outside this traditional stronghold. It should not be surprising that the machine tool builder that is probably most strongly linked with double-disc grinding technology in this country is leading the effort to take double-disc grinding into new areas. Gardner Disc Grinders Abrasives (South Beloit, Illinois) has been a pioneer in disc grinding technology from the time of its founding in 1905 as the Gardner Machine Company. Now a division of Western Atlas, Inc., the company is a leader in the field, producing both single- and double-disc grinding machines and abrasive wheels that are combined in process-specific designs.

To move double-disc grinding into a wider sphere, a major design objective for this company has been to build maximum flexibility into its machine controls. The controls are developed under an “open architecture” approach that allows upgrading and expansion for new applications, without incurring a cost penalty to these new users. Thus, these open controls had to be cost-competitive with standard control packages that have fixed capabilities.

These disc grinder controls incorporate an IBM-based, industrial hardened personal computer (PC), which is used to communicate to the motion control module. The PCs are compatible both with IBM-based boards and with widely-used softwareincluding Windows-based software on which the company plans to standardize for its next generation of controls. The motion controller used, which sends command signals to the fixture/carrier servodrives to control the grinding axes, is available in versions compatible with any computer platform. Thus, no drastic programming changes are needed to go from one platform to another.

The company also can supply a variable-speed spindle control capability that can be used with either vertical or horizontal spindle machines for specialized part applications, including those in secondary automotive and job shops where the same disc grinder will be used to run more than one part.

Precision Process Control

According to Dave Forrest, Gardner’s manager of electrical engineering and assembly, the most significant control enhancement over the past several years is the development of “adaptive gaging.” The development is important because grinding tolerances can be as tight as several millionths of an inch. To hold them, the grinding wheel has to be constantly adjusted to compensate for abrasive wear.

“With traditional contact closure gaging,” Mr. Forrest explains, “the gage reads a part to determine whether the dimensional oversize due to wheel wear has reached a pre-set limit. If it has, the gage signals the servo axes to increment the work slides by a pre-determined amount.”

The problem with this procedure, according to Mr. Forrest, is that it leads to a “saw-tooth” quality effect. The first fixed infeed increment may be too great and actually lead to undersize partsmaking it necessary to adjust again until in-tolerance parts are obtained. In time, additional abrasive wear will again tend to nonconforming parts, requiring still another adjustment. In this way, part-size cycles are introduced that are counter to the part-to-part consistency desired.

The new approach takes an analog output from the gage and compensates dynamically for the wheel attrition, making the necessary wheel adjustments “on the fly,” rather than waiting to adjust until a pre-set limit is reached, and then by a fixed amount.

The analog signal used by the control to calculate for wheel compensation communicates more than the last part gaged and the gage measurement. It provides historical data that is used for SPC and trending analysis.

New Disc Grinding Applications

These and other advanced capabilities of the process have created new application opportunities in the automotive, compressor and other industries.

One important effort is aimed at a stronger presence in the area of disc brake rotor finishing. Although double-disc grinding accounts for a very high percentage of total production, an alternate technology has emerged as a major competitor. Some automotive suppliers are now able to turn rotors to grinding tolerances, thereby eliminating the grinding step.

The use of CBN (cubic boron nitride) wheels is expected to make grinding a viable alternative in this application. According to Rictor Lundy, sales manager, Machinery Products, at Gardner, “Compared to turning, disc grinding with CBN offers better tolerances, smoother surface finish, and cost efficiencies.” Of these advantages, the improved surface finish is especially important because it determines the quality of rotor performance.

In terms of cost efficiencies with CBN disc grinding, the stiffness of the grinding machine and wear-resistance of the CBN abrasive allow more stock to be removed at reduced motor and spindle loads, resulting in lower energy costs and improved machine performance.

Another favorable cost (and productivity) factor is minimal interruption to production uptime. A CBN wheel has to be conditioned infrequently and changed less often than conventional abrasives.

For all these advantages, however, the builder recognizes that customers will be convinced of them only through comparison testing on a case-to-case basis. Tests are currently underway with one major automotive parts supplier, which plans to set up a low volume aftermarket line for disc brake rotors to compete with existing sourcesmany of which now supply turned rotors.

The parts supplier has set a criterion for the use of grindingfast changeover times in the 10- to 20-minute range. From Gardner’s point of view, this should present no special problems. “We think we can meet the requirement with quick-change tooling,” says Mr. Lundy. “Basically, it entails only the headstock fixturing and tooling used to clamp and unclamp the rotor.”

New versatility for fast change-overs is also reflected in a horizontal disc grinder now already on the floor at another major automotive parts supplier. This machine has a carrier that is configured to accommodate two different partsboth cast-iron rocker arms produced for a diesel engine manufacturer. To effect the changeover, only a secondary program has to be activated. No mechanical modifications to the tooling are required.

Productivity And Accuracy

The capability of double-disc grinding for high productivity with tight accuracies is demonstrated in a new automotive application now in the prove-out stage. Horizontal spindle, double-disc machines are used to grind both sides of two parts simultaneously by a “park and grind” method. An indexer “parks” two of the parts at a time between parallel grinding wheels, and opposite sides of the parts are ground. A servomotor is used to drive the indexer, which accelerates rapidly to park the parts, and it decelerates rapidly in removing them after grinding. To optimize surface finish and obtain necessary flatness, a “spin grinding” technique is used, by which the parts themselves rotate between the grinding wheels.

In this application, other double-disc grinders are used similarly to grind a mating part component. Because the grinding method and machines used can achieve very tight tolerances, the automotive customer believes it may be possible to eliminate the traditional practice of “classifying” the ground componentsand still achieve end-user mating requirements in assembly. Parallel and flatness tolerances being obtained in testing are in the range of 25 to 40 millionths (0.000025 to 0.000040) of an inch. Two-side size tolerance is within /-20 to 30 millionths (/-0.000020 to 0.000030) of an inch. Along with these accuracies, the production rate is between 1000 to 1100 parts an hour.

Other New Applications

Outside the automotive field, a vertical disc grinder is used at an OEM for machining hydraulic pump components. The company also is looking to expand its applications of vertical machines in grinding compressor vaneswhich are traditionally machined by spin grinding with horizontal disc grinders. Currently, a vertical disc grinder is being used for one such application at a major small-engines manufacturer.

Still another potential application outside the automotive field is the grinding of spade drills. A vertical disc grinder is now being tested in such an application against a rotary-type grinding machine. So far, one demonstrated advantage of the vertical disc grinder is superior uptime. The rotary machine can grind more parts at a time, but must be stopped for manual loading and unloading. By contrast, the vertical disc grinder never needs to be stopped, although it is also manually loaded and unloaded. Grinding is continuous, with parts always available in the grind zone.

Disc grinding machines now also are being used for grinding nontraditional materials. Glass and plastics have been disc-ground for years. A disc grinder is machining graphite components for a manufacturer in Texas. In addition, double-disc grinders increasingly are used for machining the flat surfaces of ceramic components in the computer, aerospace and other industries.

Horizontal Versus Vertical

Double-disc grinding machines can be configured vertically or horizontally. The distinction lies in the orientation of the grinding wheel spindles. On a vertical machine, the spindles are arranged one on the top and one on the bottom. Workpieces are held horizontally in a fixture that rotates between the upper and lower grinding wheels. On a horizontal machine, the grinding spindles face each other, one on each side. In this case, the workpieces are positioned vertically in the fixture.

Horizontal double-disc grinders are generally used for a mid-range of part sizes, while vertical configurations will accommodate parts from very small to the very largest. Cylinder heads, for example, can be processed using either configuration. The trend today is to grind them on a horizontal double-disc grinding transfer line, which accommodates in-line automation to other processes, has more powerful spindle motors, and can accommodate grinding wheels from 23 inches to 42 inches in diameter.

A number of processing variables must be considered, however, in selecting between the horizontal and vertical configurationsincluding requirements for production rate, stock removal and automation. For example, a horizontal double-disc grinder can process a typical 6-inch connecting rod at a production rate of 1200 per hour, while a vertical configuration will be limited to approximately 300. On the other hand, vertical double-disc grinders often require less floor space and typically offer broader flexibilityfor example, for changeover to a different carrier.

Both configurations are highly productive and equally easy to maintain, with the same level of control technology and advanced features available for their respective applications.

Double Disc Diamond CBN Grinding Wheel

Superhard diamond / CBN grinding disc including resin diamond / CBN grinding disc, vitrified diamond / CBN grinding disc, double-disc surface grinding disc, pellet grinding wheel and so on.

Superhard diamond / CBN grinding disc including resin diamond / CBN grinding disc, vitrified diamond and CBN grinding disc, double-disc surface grinding disc, pellet grinding wheel and so on.

Diamond grinding wheel, is suitable for grinding carbide, tungsten steel, PCBN high hardness of the workpiece ,ceramic. optical glass, sapphire glass and other nonmetal materials. CBN grinding wheel, is suitable for high speed steel, bearing steel, tool steel, stainless steel. powder metallurgy, precision grinding mill cast iron and other hard materials.

Application fields of diamond/ CBN grinding disc

Cylinder Block (Grey Cast Iron or Nodular Cast Iron), Sleeve (Alloy Cast Iron), Slide (High Speed Steel). piston.

Dressing Wheel For Diamond And CBN Wheel

The dressing wheels are used for dressing diamond and CBN wheels. According to the different particle size, accuracy of the diamond and CBN grinding disc to choose the dressing wheel, making dressing easier and more time saving.

The case of Diamond / CBN grinding disc, pellet grinding wheel

The customer tested surface roughness of workpiece by MarSurf M 400. The results show that the workpiece has the much stable performance and good surface roughness by using our diamond grinding disc.

Sources:

https://patents.google.com/patent/US4462187A/en
https://www.ctemag.com/products/double-disc-grinding-cell
https://www.mmsonline.com/articles/double-disc-grinding-on-the-move
https://www.moresuperhard.com/show.asp?ID=26

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