JOEST Special Charging Feeder

The material loaded into the feeder contains some fines delivered with the material as well as fines picked up by the bucket loader when it scoops material up from the storage piles.  This requires a screen deck section with a collection bin below it to hold the fines.  The holding bin had to be designed to store a reasonable amount of material so it does not have to be emptied often, but it also had to be located so that a forklift can easily and quickly exchange it.

 In addition to the scrap material, the feeder must also feed alloy material that ranges in size from 5mm to 300mm.  The alloy material can be smaller than the openings in the screen section used to remove contamination fines, so the alloy material cannot pass over the open holes of the fines screen.  Joest evaluated several previously proven ways to mechanically close the openings in the screen section when feeding the alloys.  Due to the characteristics of the alloys, these methods were complicated, costly and could have difficulty repeatedly sealing the openings.  While cost effective, replacing the perforated section with a solid plate when running alloys was not practicable because of the size and weight of the blanking plates and frequency of performing this operation.

The solution was to design the feeder pan with an additional, parallel solid pan that runs the length of the feeder and bypasses the fines screen section.  The infeed hopper had to be designed to allow the alloy material to be easily loaded with a bucket loader into just the bypass portion of the feeder.  As an added feature, the alloy loading area was equipped with a perforated cover on top to screen out any oversized alloy material, as well as any scrap material that may accidentally fall into this area.

As a result of the asymmetric pan, this design had to accommodate off-centered loads on the drives, maintain adequate openings for loading the scrap and alloy materials, and achieve the desired throughputs.  All this was accomplished while limiting the width of the feeder to be less than the width of the furnace.

Traditional charge cars run automatically on a set of rails.  Special bumpers with sensors ensure safe operation when personnel and obstructions are in the path of the car’s movement.  Unfortunately, the cost of the automation portion of this solution was not within the customer’s budget.  Also, the floor was too rough to reliably keep debris from getting into the rail bed and interfering with the cart’s wheels.  Splattering metal from the furnace may also get on the rail bed. The resulting need and frequency of cleaning the rail bed was also a factor.

Manual, free-form movement of the feeder was chosen.  Increasing the weight of the cart ensured the cart would not move when set on the ground, but the added weight now exceeded the lift capacity of the current forklifts.

The feeder frame was designed so it can be pushed by lifting one end with a forklift while the other end rolls on retractable wheels.  The size and type of wheels were chosen to accommodate the rough floor.  The handle and gear ratio of the wheel mechanism were chosen to make the extension and retraction of the wheels easy and ergonomic.

It took serval iterations during the concept engineering phase of the project to identify and pull all the solution features into one design.  The customer was forthright with the different design requirements and an integral part of the brainstorming, evaluation and concept engineering phases.

There are several companies that can make a simple, standard feeders, but few who have the industry experience, engineering capability, and creative problem solving skills to make custom solutions to totally satisfy all the customer’s needs.  This custom design work then feeds back into the process to make better standard solutions and continually help Joest to push the limits to meet the next, even greater challenge.