Joshua Bigwood & Son Limited

Straightening Machines

Bigwoods designed and constructed plate straightening machines for many years. The machines were grouped into two categories. The first was for dealing with plates or sheets up to three sixteenths of an inch thick. These machines were usually equipped with thirteen or seventeen straightening rolls. The second category was for machines dealing with greater thicknesses. These were usually provided with seven or nine straightening rolls. The largest of the machines could deal with plates up to 2.5 inches thick and any width.

A plate straightening machine for dealing with thick plates

The bearings on both the straightening and supporting rollers had water cooled bearings and the top rolls were operated by an electric motor which was push-button controlled. Precision hand adjustment was provided for the inlet and outlet rollers and the degree of adjustment was precisely registered on a large dial. The drive from the motor was via a totally enclosed, self-lubricating gearbox and other bearings were equipped with a pressure grease system. The strong construction was reinforced with steel tie rods. 
In the smaller machines the straightening rollers have an extra large diameter to avoid any undue deflection when straightening thin and narrower plates. The rollers were driven from a simple, reliable gear drive and were easily and accurately adjusted using a graduated indicator dial. The use of a gear drive with double helical teeth ensured smooth and vibration-less running.

A smaller plate straightening machine

The S.M.16 shape and section straightening machine with 9 rolls.

The shape and section straightening machine was designed to straighten large quantities of bars in a large-scale production system. The top rollers were vertically adjustable to deflect the material to be straightened and horizontally adjustable to enable complicated sections to be dealt with. Each machine was supplied with a set of rollers to suit the customer's own requirements and all gearing was of cast steel and all bearings had bronze bushes. The speed of straightening depended upon the shape of the section and the nature of the material.
The S.G.5 shape and section straightening machine with 8 rolls.
The S.H.8 shape and section straightening machine with 8 rolls.
The S.K.10 shape and section straightening machine with 8 rolls.
A motor-driven S.H.8.
The Bigwood high efficiency multiple roller sheet straightening machine could perfectly flatten buckled and dished sheets and remove all rolling and stretcher strains. The machine was easily adjustable using the hand wheels on the front of the machine, each of which was provided with an indicator. Lubrication was centrally provided by a pressure grease system and finger guards were provided to safeguard the operator. 

A high efficiency 17 roll sheet straightening machine

No. OA tube and bar straightening machine

The No. OA tube and bar straightening machine could straighten any bar up to seven eights of an inch diameter and any tube up to one inch in diameter at a speed of 300 feet per minute. The rollers were adjustable both horizontally, vertically and in an angular direction to ensure that alloy heat treated steels could be straightened in a perfect manner. All bearings were covered to prevent the entry of dirt and a special flood lubrication system and oil bath was included. The machine could be driven from a belt or electric motor. 7 hp. was required for dealing with tubes and 10 hp. for bars.
A hand operated straightening machine.
The following four photographs were kindly sent by Terry Pringle. They show a working M.R.L. 4 plate levelling machine that is still in use. As can be seen, it is a typical heavy-duty, well-built Bigwood product, designed to have a long and reliable life. It is lovely to see a well looked-after Bigwood machine, still doing what it was designed to do.

I must thank Terry for his excellent photos.

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