Thursday, January 20, 2011 | News
C & B Machinery has been awarded an order by Allison Transmission to build a “Flexible” double disc grinding cell for its Chennai, India facility; Allison Transmission India Private Limited.
The grinding cell is designed to grind the faces of transmission pinion gears for Allison’s 1000 and 2000 series transmissions. Double disc grinders remove equal material from both faces simultaneously. This particular machine will be arranged to grind four various pinion configurations with the capability to grind 11 more already being produced at the plant (on grinders previously provided by C & B).
The machine employs a “rotary plunge” grinding cycle which means the pinions are introduced to the grinding wheels via a rotary carrier one at a time while the grinding wheels plunge grind simultaneously through axis interpolation. There are several advantages for grinding in this manner, with the most important one being that the grinding wheels are adjusted perfectly parallel and concentric to each other. (Conventional double disc grinding most often requires compound head settings.) Keeping the wheels parallel results in more uniform wheel wear and reduced frequency of dress cycles; ultimately saving in abrasive expenditures. Cost per piece is reduced and return on investment is quicker.
This grinding cycle, developed by C & B engineers also allows 100% gage feedback on every component ground. Size control is tightened resulting in higher statistical capability. For example the grinding cells previously shipped by C & B far exceeded 2.0 Ppk in OAL (± 0.030mm) and parallelism (0.026mm).
The entire grinding cell including the grinder, automation, gaging system, coolant system and even the production (bench) gages are provided and integrated by C & B Machinery.
“Flexibility is a very strong requirement for customers today. In parallel, it is now one of the main selling features of C & B Machinery’s grinding systems as well as our very company”. These special grinding cells are designed to change over from part to part in as little as three minutes. Considering that production double disc grinders have been historically dedicated machines, it is quite an about face.
“The most important aspect of this project is to convey on a global scale, that the American Machine Tool Industry is still alive and well. We have the talent base and the ingenuity to compete globally and produce and support some of the highest quality and most flexible grinding systems available anywhere in the world.”
Monday, December 20, 2010 | News
GRINDING VOLT RODS
Traditionally, only coplanar, or parallel, connecting rods have been ground on a double-disc grinder, which simultaneously grinds both sides of flat parts using opposing wheels, according to grinding machine builder C&B Machinery. That’s because the part path through the wheels only allowed grinding of coplanar rods, with additional operations required for stepped rods, and there was no method to dress a step into the grinding wheels.
However, General Motors sought a machine that could grind a noncoplanar connecting rod in a single setup for the auxiliary 1.4-liter engine in the Chevy Volt plug-in hybrid electric vehicle. GM requested a quote from C&B for two such machines. (The crank end is 1.2mm narrower than the pin end on the turbo version of the connecting rod.)
After analyzing alternate methods of double-disc grinding and material handling, C&B developed a CNC double disc grinder to remove 1.8mm of stock from the crank end and 0.6mm from the pin end in one cycle. According to the company, the process is unique and represents the first successful attempt to grind a stepped connecting rod with this technology on a production basis.
By grinding two different widths on one connecting rod in a single pass through the machine, GM saves the cost of buying another machine to reduce the crank end –and improves part quality, noted Chris Cox, C&B vice president. “When processing connecting rods of this type on two different machines, which is a more conventional approach, it is very difficult to hold the relationship, or symmetry, of the faces from crank end to pin end,” he said, adding that parts float between the wheels in a double-disc grinder and are not clamped. “By grinding the four faces simultaneously we were able to hold much tighter tolerances.”
The first grinder shipped to GM in 2010 produced flatness and parallelism of the rod faces within 4-microns on average, repeating within 1-micron! Size range is held within 25% of print tolerance and repeats within 3-microns. The step relationship from crank face to pin face is held within a range of 6-microns.
This state of the art Grinding System is equipped with a robot that places the ground parts into an automatic gauging system that 100% inspects the crank end thickness, pin end thickness and step relationship. The system is designed such that the grinder will automatically correct itself should any of the three characteristics drift beyond preset limits.
The entire cell which is comprised of the grinder, automation, robot, gauging system and coolant filtration system is monitored and controlled by a single Human Machine Interface (HMI).
Similar to the Volt getting better mileage than cars powered only by gasoline, Cox noted that the motors on C&B’s special double-disc grinding machines require less energy than conventional machines due to the process using 25% less horsepower.
For more information, contact C&B Machinery, Livonia, Mich., at (734) 462-0600 or www.cbmachinery.com.
Thursday, December 9, 2010 | News
As part of its ongoing effort to diversify its customer base, C&B Machinery has developed a double-disc grinding system equipped with diamond-impregnated grinding wheels arranged for grinding the faces of various ceramic discs used in the telecommunications and permanent magnet industries.
The Model CBV2-16-R/B is now in use at Island Ceramic Grinding in Gilroy, Calif. The machine is actually a re-engineered system developed from a used machine carcass, but now designed to increase quality and product throughput, thereby reducing unit production cost. During runoff, the grinder achieved production rates of 300 parts per hour, effectively doubling output over previous grinding methods.
Double-disc grinding involves removing material from a part with parallel surfaces. The stock removal takes place on both faces of the component simultaneously, with the grinding occurring on the faces of the grinding wheels. Disc wheels are attached to diametrically opposed spindles, each contained in a heavy-duty precision grinding head assembly. For this particular process the spindles are vertically opposed and the parts are introduced to the grinding wheels via a rotary carrier system.
The design challenge for C&B Machinery was to provide a solution that fit within Island Ceramic Grinding’s budget. “A typical re-engineered grinding system means starting from a blank sheet of paper and completely stripping the machine of all commercial and most OEM components,” according to Chris Cox, vice president at the machine builder. The solution involved adapting new state-of-the-art feed systems and CNC controls to the machine, along with newly designed tooling. The result is essentially a turnkey system that is 20-30% less expensive to acquire than a comparable “new” machine.
In this case, C&B Machinery scaled back the updates in order to meet the customer’s budget. A simple PLC control replaced relay logic, and the mechanical wheel-feed systems were remanufactured and reinstalled. Careful attention was paid to balancing the spindles, which is critical to grinding with super abrasives.
The grinding wheel spindles were outfitted with variable-frequency drives that allow the grinding wheel surface speed to be programmable. Changing the speed of wheels, in essence, changes the “hardness” and cutting characteristics. This is a useful for adapting to changes in the material to be ground or variations in stock removal.
“Considering the expense of diamond grinding wheels, the ability to program the speed of the wheels allows easier and more cost effective optimization of the grinding process. It limits the necessity to experiment with and stock multiple grades of grinding wheels,” Cox explained.
Also, the machine is also outfitted with new digital readout displays for the grinding axes. This allows the operator to make very small adjustments (0.000050 in. increments) for precise size control.
Precise alignment of the wheelheads and tooling make it possible to achieve extremely flat and parallel parts, as compared to more conventional surface grinding methods.
“The trick to grinding ceramic components on a double disc is not to be in a hurry. In other words,” Cox continued, “the stock removed from the part is very small as compared to metal components. This is in order to keep the parts from chipping or even disintegrating when they enter the grinding wheels. Depending on the parent stock, multiple grinding passes may be required. Even still, this is a much faster method of producing higher quality parts than conventional surface grinding. It doesn’t hurt to have hundreds of years of grinding experience either.”
Thursday, September 30, 2010 | News
C&B Machinery has been contracted by General Motors to supply two special, double disc-grinding systems to finish-grind both coplanar and non-coplanar connecting rods for the auxiliary 1.4-liter engine in its new electric-powered Chevy Volt.
The Volt is a plug-in hybrid electric vehicle that GM will introduce later this year, to be powered by electrical energy supplied by on-board lithium-ion batteries that are charged by connection to an electrical outlet. The car’s 16-kWh lithium-ion battery pack can be fully charged by plugging the car into a residential electrical outlet. The gasoline engine is installed as a backup power system.
C&B Machinery designs and builds grinding machines for automotive and other high-volume applications. Along with its line of double disc grinding systems, it rebuilds and services other major brands of grinding machines.
Double disc grinder machines grind both sides of flat parts at the same time, using opposing wheels. The C&B Double Disc Grinder is equipped with horizontal spindles. All four faces of the Volt’s connecting rods are ground simultaneously to extremely tight tolerances. The Turbo version of this connecting rod has unparallel (or non-coplanar) surfaces, with the crank end 1.2 mm narrower than the pin end.
The challenge of the design was to produce this non-coplanar connecting rod from a parallel or coplanar rod. C&B Machinery developed this grinding system to remove 1.8 mm of metal stock from the crank end and 0.6mm from the pin end — in one cycle. All four faces are ground simultaneously, and the production rate is roughly 200 parts per hour.
According to C&B’s information, this grinding process is unique. Similar, conventional methods have been attempted by other manufacturers in the past, but never have proved successful.
The first grinder shipped to GM earlier this year produced flatness and parallelism of the rod faces within 4 microns on average, repeating within 1-micron. Size range is held within 25% of print tolerances and repeats within 3 microns. The step relationship from crank face to pin face is held within a range of 6-microns, C&B states.
This state-of-the-art grinding system is equipped with a robot that:
- Unloads finish ground parts;
- Positions every part in front of a camera, which ensures the part, is oriented correctly; and
- Places the part into an automatic gauging system that fully inspects the pin-end thickness, the crank-end thickness, and the step relationship.
Traditionally, C&B explains, only coplanar connecting rods (pin end and crank ends are the same width) have been ground on double disc grinders. Additional grinding steps have been needed for stepped or “non-coplanar” connecting rods. On the C&B grinder, two different widths on the same connecting rod can be ground in one pass through the machine, saving time, improving quality and reducing costs.
The machine also makes a positive impact on the environment: it has no hydraulics, its motors require less energy than more conventional machines, and the coolant filtration system uses no disposable filter media.
Monday, September 27, 2010 | News
C&B Machinery has been awarded an order by GM for two special double disc grinding systems to finish grind both coplanar and non-coplanar connecting rods for the auxiliary 1.4L engine in the electrically powered Chevy Volt.
Double disc grinders grind both sides of flat parts at the same time using opposing wheels. The C&B Double Disc Grinder is equipped with horizontal spindles. All four faces of the Volt’s connecting rods are ground simultaneously to extremely tight tolerances. The Turbo version of this connecting rod has unparallel (or non-coplanar) surfaces (the crank end is 1.2mm narrower than the pin end).
The challenge was to produce this non-coplanar connecting rod from a parallel or coplanar rod. C&B Machinery developed this grinding system to remove 1.8mm of metal stock from the crank end and 0.6mm from the pin end in one cycle. All four faces are ground simultaneously, and the production rate is roughly 200 parts per hour.
This grinding process (to the best of C&B’s knowledge) is unique. Similar, conventional methods have been attempted by other manufacturers in the past, but never proved successful.
The first grinder which shipped to GM earlier this year produced flatness and parallelism of the rod faces within 4-microns on average, repeating within 1-micron! Size range is held within 25% of print tolerances and repeats within 3-microns. The step relationship from crank face to pin face is held within a range of 6-microns.
This state of the art Grinding System is equipped with a robot that:
- Unloads finish ground parts.
- Positions every part in front of a camera, which ensures the part, is oriented correctly.
- Places the part into an automatic gaging system that 100% inspects:
- Pin end thickness
- Crank end thickness
- Step relationship
- Places the part in the outgoing automation
Traditionally, only coplanar connecting rods (pin end and crank ends are the same width) have been ground on double disc grinders. Additional grinding steps have been needed for stepped or “non-coplanar” connecting rods.
On the C&B grinder, two different widths on the same connecting rod can be ground in one pass through the machine, saving time, improving quality and reducing costs.
Like the Chevy Volt, this machine employs the use of Green Technology. There are no hydraulics on the machine and the motors used require less energy than more conventional machines. Additionally the coolant filtration system uses no disposable filter media.
General Motors is to be commended for its faith in a hometown manufacturer to get the job done.
C&B Machinery designs and builds production grinding equipment for automotive and other high volume grinding applications. In addition to its own line of double disc grinding systems, the company rebuilds and services other major brands of grinding machines. C&B is privately owned and employs a highly trained staff of service technicians, machine builders as well as in-house control and mechanical engineers.
Monday, July 26, 2010 | News
C&B Machinery’s latest Non-Coplanar Connecting Rod grinding system does the work of three machines.
C&B Machinery of Livonia, Michigan has improved productivity and flexibility of their double disc non-coplanar connecting rod grinding system first introduced in 2009 for the Chevrolet Volt 1.4L auxiliary engine.
The first grinding system produced a stepped connecting rod from a parallel (or coplanar) rod. The 1.4L Chevy Volt connecting rod has a 1.2mm symmetrically smaller crankshaft end width, and both the pin and crank ends of the rod are ground in one sequence. At the time, the system was considered the most advanced double disc grinder ever produced by C&B.
This latest system, recently shipped to Eston Manufacturing Division of Linamar Corporation, is grinding a 1.8L connecting rod with a symmetrical reduction of the pin end of 3.8mm. As before, the challenge was to produce this part from a coplanar connecting rod in one operation. Stock removal from the pin end of the connecting rod is 5mm and stock removal from the crank end is 1mm. Previously, this connecting rod required three grinding operations to complete and the crank and pin end were ground on two separate machines.
C&B’s application engineers took the challenge to task developing a special tooling package and unique 2-stage grinding cycle which first rough grinds the pin end to a stock condition equal to the crank end. It then finish grinds the crank and pin end of the connecting rod simultaneously. Grinding the crank and pin ends at the same time produces much better symmetry between the two. Additionally the grinder easily exceeds Eston’s 1.67 Ppk requirements for size, parallel and flatness.
The grinding system also includes a post process gaging system with automatic feedback to the grinding wheel infeed servos providing automatic compensation for wheel wear. The gage also inspects step relationship between the crank and pin end faces.
The C&B model DG2H-SA/30 Connecting Rod grinding system has the ability to grind parallel parts, non-coplanar parts, pin end only or crank end only configurations with very simple changeover. This bodes well with today’s manufacturing requirements — lower production rates, better flexibility and a never-ending demand for lower machining costs per piece.
With models utilizing up to 42” diameter grinding wheels, large diesel connecting rods can also be produced in this manner.
