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Strikes to spare

Strikes to spare

The bowler stands on the line, arm high in the air. Here's the windup, and then the release. There goes the ball, rolling down the alley and hooking into the pins. Steve Jaros gets a strike.

Well, sort of.

ThrobotTM, a bowling-ball testing machine, actually got the strike, imitating Jaros' throw style and rolling the ball perfectly up the alley. The machine features an unprecedented combination of technologies. It combines hydraulics, pneumatics, and electronic sensors.

Why have a machine test bowling balls? Before the invention of Throbot, Brunswick Indoor Recreation Group (Muskegon, MI), which produces about 1 million bowling balls a year, used its Pro Staff and bowlers from other cities to test its new bowling ball coverstocks, the plastic shells that cover the core of the bowling ball. Human bowlers weren't always available, and when they were, they presented a variety of bowling styles. That variety, plus varying lane conditions, made completely objective evaluations impossible.

Brunswick wanted a more objective, reliable, and precise way to test balls. Enter Throbot, a 20-ft-long, 10-ft-high, and 5-ft-wide machine that weighs 1,600 lb and is controlled by a Windows-based program. The program allows the tester to set variables, such as the ball's rotation, loft, firing angle, axis position, axis tilt, release height, and release direction. Rpm is also variable, and ranges from 0 to 1,200.

Using the same variables, Brunswick can detect variations in ball coverstocks and compare variables in the ball itself, such as holes versus no holes. Also, the machine can help the company with lane-oil and surface research.

"It can help pick the most promising coverstocks, what bowlers want, because it's so objective," says Klaus H. Sommer, vice president of research for Bayer's Polymers Div. Bayer collaborated with Brunswick on the conceptualization of Throbot and built the machine at its Leverkusen, Germany headquarters.

The first coverstock to be developed using Throbot is AxiomTM Proactive UrethaneTM, which is chemically different than current reactive resin formulations. The coverstock improves traction effect, contact between the ball and lane in the presence of oil, which increases hook potential, according to Bill Wasserberger, director of R&D for high-performance balls for Brunswick.

"The Proactive technology is a way of working with surface microtextures, which has some analogies to treads in tires, which allows us to additionally change performance characteristics," Wasserberger says.

The coverstocks that came before Axiom were like a bald tire with no treads, Wasserberger adds. "They would grip the dry part very strongly but hydro-plane more readily in the wet part of the lane," he says. "Just like in tires, if you introduce a tread, it allows you to traction through the water better."

The development of Axiom is only one part of an ongoing effort to design a better ball. "There's a continuous move to create better bowling ball materials," Bayer's Sommer says. "We've had great success if you look at our track record, and a number of dramatic improvements in the resin, but we have more improvements to make."

Wasserberger agrees that there is indeed room to design a better bowling ball. "We can work with urethane coverstock chemistry and the internal mass distribution of the ball," he says.

Engineers design bowling balls using CAD solid modeling, where the designer can play with the mass distribution. Brunswick engineers can model shapes on the inside of the bowling ball to be used as its core, then assign densities, and the computer will give a mass properties readout. This includes masses, or gross weights; center of gravity position, or where the core should be placed within the ball; and moments of inertia; which describe the ball's rotational dynamic characteristics. "It's those changes in the moments of inertia structure that also produce performance changes on the lane," Wasserberger says.

In the 1990s, Brunswick started putting additives into the urethanes to change performance characteristics. These urethanes, called reactive urethanes, are modified with additives that are not necessarily bonded-in chemically. "As you tend to fill up the coverstock with more and more additives, you tend to reduce the durability, although you increase hooking action," Wasserberger says.

However, durability is not as important to some people. "The people who pursue the sport on a high level are willing to trade improved performance for less durability," he adds.

When the coverstock starts cracking due to the type of use it has been put in depends on the type of coverstock material. Most of Brunswick's balls last for 200 to 300 games. The most durable material used in balls is a urethane material, which was used in the 1980s, Wasserberger says, and adds that balls made of this material can last for 400 to 600 games. However, this material does not perform as well as the 200 to 300-game material, he adds.

The wonder ball. When Throbot tests these balls, it can repeat throws one after another, and can imitate the bowling styles of both right- and left-handed bowlers, Sommer says.

The machine is a pendulum-type device, featuring a hydraulically actuated 8-ft pendulum. A chucking device within the machine holds the ball in place. Throbot also features a pneumatic braking system that keeps the pendulum from going all the way to the top of the machine when it winds up. Suction cups keep the machine adhered to the floor.

Two hydraulically operated shelves clamp the ball in place and are connected to a motor. The shelves spin the ball, and when the pendulum is at its release point, the shelves open, and the ball is released down the alley.

But the system doesn't stop when Throbot releases the ball. A 24-sensor computer-aided tracking system called Super CATS measures the speed and position of the ball at 24 points down the lane. Super CATS can reconstruct the ball's trajectory by putting together the information from each sensor point. The sensor system can measure the difference between ball coverstocks, lane surface preparations, and differences in the ball's y-point.

Building with Bayer. In 1995, Brunswick started talks with Bayer Corp. about developing a machine to test bowling balls. Bayer had already developed a mechanical ball launcher in their Leverkusen, Germany lab. However, the hand-operated mechanical ball launcher could not spin the ball or orient the axis of rotation of space, nor was it computer-controlled. Bayer AG, Bayer in the U.S., and Brunswick were partners in design.

Bill Wasserberger and Ray Edwards, development engineer for Brunswick, worked with Sommer to conceptualize the chuck-type device that holds the bowling ball in place.

The team created a series of specifications for the release characteristics the machine would have to handle, such as the amount of side roll, axis orientation, velocity, and release heights. "Ray and I came up with those based on our knowledge of bowlers in general and the ranges we thought we'd be able to work in," Wasserberger says.

After the team came up with the concept of the chucking-type device and the machine's pendulum, Brunswick turned the engineering project over to Bayer in Germany, who worked out the details of how to design the machine and its execution and testing, Wasserberger adds.

The original discussions were between Brunswick and Bayer Corp. in Pittsburgh. The two companies communicated via meetings, phone calls, and video conferencing. Bayer Corp. and Bayer AG in Germany worked together on how to design the machine, and ultimately all three corporations worked together very closely, Sommer says. Physicists and chemical engineers worked on the project in the U.S., and mechanical engineers worked on it in Germany.

Bayer built the machine in six months. It was shipped from Germany to Michigan upon completion.

"We had to go through the logical process of defining operating specifications, and the Bayer engineers did a wonderful job of executing the concept and meeting those specifications," Wasserberger says.

So good, in fact, that the machine showed what it could do the first time out. He adds, "When we finally got it on the lane, the first ball it threw was a strike."

Throbot's vital signs

  • Length: 20 ft

  • Height: 10 ft

  • Width: 5 ft

  • Speed range: 0 to 21+ mph

  • Revolution rate range: 0 to 1,200 rpm

  • Side roll: 0 to 90 degrees

  • Axis tilt: 0 to 30 degrees *

  • Loft: 0 to 10 ft

*(limited by release height of ball)



Talks begin between Brunswick and Bayer.

March 1997

Bayer AG in Germany begins to work on the machine.

August 1997

Bayer completes work on the machine.

September 1997

The machine arrives in Brunswick's Muskegon, MI headquarters.

June 1998

Brunswick and Bayer announce Throbot.


You can reach the following companies mentioned in this article on the Internet at their listed web address. Please tell them you were referred by Design News.

Brunswick Indoor Recreation Group:

Partners in design

Here is a list of suppliers for some of the Throbot's many parts:

Vacuum pump and four suction cups for fixing the bowling machine to the basement:

PIAB Vakuum GmbH, Buchholz, Germany

  • Hydraulic motor with control unit for moving the pendulum arm: Pleiger Unternehmensgruppe, Witten, Germany

Dc motor with gear unit for rotating the ball:

  • Mattke GmbH, Freiburg, Germany

  • Pneumatic brake for stopping the pendulum:

  • Binder Magnete GmbH, Villingen Schwenningen, Germany

Digital angle encoder for measuring the angular position of the pendulum and of the axis of the ball rotation:

  • Baumer Electric, Friedberg, Germany

Pneumatic cylinder for clamping the ball:

  • Festo Pneumatic, Esslingen, Germany

Digital position encoder for measuring the release height:

  • Wintec Messtechnik, Schondorf, Germany

Programmable logic control:

  • Mitsubishi Electric, Ratingen, Germany

PC with A/D-converter board:

  • Hewlett-Packard GmbH, Boeblingen, Germany

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