1. Introduction

The design suggests developing an automated machine to harden the face surface of a cricket bat while it is being transported to the final stage of production. This stage of hardening cricket bats has traditionally been a tedious and labour intensive process actually performed by the consumer using a rubber mallet to knock and harden the surface. This action compresses fibres in the face, edges and toes of a bat and knits them together to form a harder barrier to the impact of a cricket ball. The hardening is done as a means to prevent cracking and fracture of the bat and so enhance its life and performance. This competition entry suggests a mechanised system to perform this function.

To date there are some machines that can perform this process after purchase. However they are still manually operated, require time from the customer and can be expensive due to their limited availability. They also do not offer the opportunity to customize the depth of hardened surface and the surface is often not uniformly hardened. These facts illustrate a gap in the market that can be exploited for financial gain while offering a means to further improve service standards in sporting equipment.

2. Thinking About the Theory Behind Cricket Bats

2.1. Cricket Bat Regulations 

The design of the Automated Hardening Machine needs to take the specifications of cricket bats into account. The Marylebone Cricket Club (M.C.C.), the acting Guardians of the Laws of Cricket, state very specific regulations for the size of cricket bats, click here for more information.

2.2. Cricket Bat Knocking-In Procedure 

Cricket bats are made from a fairly soft and fibrous material called willow or Salix Alba Caerulea. With cricket balls being delivered at a high velocity at up to 140km/h or approximately 39m/s against the face of the cricket bat, it is obviously advisable to prepare a bat so as to achieve optimal performance, resistance and longevity. This process is referred to as knocking or running in a cricket bat.

The knocking-in of a bat requires three functions to be performed on a bat namely, oiling, rolling and knocking-in.An important part of the knock-in procedure is to knock-in the edges as this is a common place for a crack to start occurring. This is done by turning the bat along the handle’s axis and hitting the edges of the face at approximately 45° with the mallet or ball.

3. Specifications

The project entry went to great lengths to identfiy and list potential customer specifications, engineering and tooling specifications, for example:

3.1. Customer Specifications  The rolling and knocking procedure must incorporate a means of varying the applied force of the roller and thus the compression of the bat. Before and during rolling and knocking 10ml of linseed oil must be applied to the bat surface every second sweep The heel/toe and edges of the bat must also be rolled at 45°. The design must have a simple but functional design using as many off the shelf components to reduce machining time and cost.

3.2. Engineering Specifications  The cricket bat must be held firmly, whilst being moved in two axes, while certain operations are being performed on it. The positioning of the cricket bat in the x and y axes, whilst the processes are being performed, is important and must have an accuracy of less than 1mm. The system must be reconfigurable for a range of cricket bat sizes.

3.3. Tooling Specifications  The design must be versatile; it must be able to perform the knocking and rolling process for a variety of sizes, weights and thicknesses of cricket bats. To maximize productivity and reduce material handling, the machine must be able to accommodate multiple products being processed simultaneously. The edges and toe of the cricket bat must be knocked at an angle of 45° to prevent cracking and fracture.

4. Reviewing Some Design Concepts 4.1. Track Automation (X-Axis Movement)   A number of different ideas were presented for using a servo gear motor for the purposes of moving the carriage along the X-axis. For example: * An On-Board Motor  Mounting the gear motor directly onto the carriage itself with a pinion or wheel. * Chain Driven  A chain drive could be used to circulate the track of the carriage. * Ball-Screw  A ball-screw drive unit could be employed to rotate a threaded shaft axially along the X-axis. This proposal would eliminate the need for a moving motor or extra space. 4.2. Lifting Mechanism (Y-Axis Movement) This aspect of the design involved the need to lift the bat in preparation for a uniform hardening process. Two design suggestions were made. Presented here is an Electric Cylinder to be used to accurately position the cricket bat during the knock-in process. The electric cylinder is capable of putting out a large force in relation to the accuracy it provides.
4.3. Pick and Place Mechanism The following two design ideas were presented to accomplish the “pick and place” requirements: * Pneumatic Gripping Mechanism  The first idea proposes two parallel paddles, shaped to pick up a cricket bat using a pneumatic parallel gripper. Figure 13 shows how Festo’s HGP-20-A-B unit could be arranged with gripper and paddles. This mechanism would be able to pick up and grip the bat firmly by the handle while the hardening procedures are taking place. However, a disadvantage was noted in that the bat would need to be supported along the length of its back during the rolling and knocking-in procedure. * Suction Cups  Figure 14 illustrates the use of suction cups to lift (pick and place) the cricket bat. Once the transporting carriage has moved away from the pickup zone, the bat could be lowered and released onto a “negative” of the back of a bat, thereby allowing full support while the rolling and knocking-in procedure takes place.
4.4. Bat Tilt Mechanism The correct knocking-in procedure requires the force of the knock to come at 45° to the normal direction of the surface of the bat, requiring the bat needed to be tilted 45° in either direction. Various options regarding the choice of actuator were explored such as an Electric Cylinder; Twin Fluidic Muscles; and a Pneumatic Cylinder. Regulating the position of the bat with a proportional valve was also discussed.
4.5. Rolling  / Hardening A rolling process can compress and toughen the face of the bat for competition. The willow of a potential bat may still be very soft coming off the shelf and this helps prevent seam marks and “dings” damaging the bat. The students incorporated a number of design ideas together to propose making use of a braced cantilever frame constructed of square tubing, bolted and welded together. The resulting frame can be light, less prone to bending, is simple and east to assemble. The support guides for the rollers are mounted from below the cantilever frame and are connected together by a common shaft. Between the sleeves a single cylinder is mounted which will control the roller on the bat's surface. The pressure is controlled through a proportional valve connected to the controller hub.

4.6. Knocking / Hardening 

This process requires the simulation of a hard ball hitting the blade squarely. This, in its own right, plays the part of also preparing the willow for use. This is often done by repeatedly hitting the ball, first softly for about two hours, and then by using a "bat mallet" for about 8 hours, getting progressively harder as bat is being knocked-in.

The students presented four different concepts for this process, ranging from simple to relatively sophisticated, all well though-out and each with its own advantages.