Hoisting appliance design and brickwork of pit furnace bottom

1、 Design of Hoisting Device for Well type Furnace

Fixture plays a very important role in heat treatment operation, especially in the well furnace operation, it is inseparable from the starting fixture, and has a close relationship with the quality of heat treatment. The heat treatment fixture is usually heated and cooled together with the workpiece, which needs to be reused, and is prone to oxidation, deformation and cracking. At the same time, it also takes away some heat, accounting for 2-3% of the total heat, which undoubtedly increases the production cost of heat treatment. Due to unreasonable fixture design and material selection, problems such as high defective product rate, high heat treatment cost and low production efficiency are common, and there are certain potential safety hazards.

Combined with the structural characteristics of common parts, furnace loading method and the placement position in the furnace during heating, according to the "building block" design idea, the designed lifting appliance adopts a split structure, as shown in Figure 1. The disc, base and adjusting sleeve are connected in series by the suspender. According to the size, weight and shape of the workpiece to be processed, the flexible adaptation of the level, height and loading capacity of the spreader can be realized by changing the adjustment sleeve and combining it at will. The grid hole design on the spreader can realize the free suspension and stable fixation of the workpiece, ensure the fluidity of the atmosphere in the furnace, and meet the requirements of uniform heating and cooling, so as to ensure the uniform hardness and small deformation of the workpiece after heat treatment.

The advantages lie in the simple handling and assembly of each component of the lifting appliance, the simple commissioning and maintenance, and the safety and reliability, so as to avoid potential safety hazards and quality accidents caused by workpiece slipping during the lifting process.

In addition, both the front and back sides of the disc can be used with interchangeability. The lacing wire can effectively control the deformation of the spreader and improve its service life.

The charging and discharging processes of carburized workpieces are generally operated at relatively high temperatures, so the requirements for slings are high: accurate positioning, safe and reliable hanging, time-saving and labor-saving, light and flexible, convenient operation, and sufficient strength and stiffness to prevent deformation and cracking. The common slings are generally used with two or four foot slings and the material frame. The safety and reliability are poor. When the furnace is out of the furnace, two workers stand beside the furnace bench and one person conducts the operation command. With experience and feeling, the material frame is hooked for a long time. A little carelessness will burn the face by high heat waves. Sometimes, the frame will be overturned due to improper lifting caused by the deformation of the slings, which will bring certain losses to personnel, equipment and quality.

In addition, because the workpiece is always in a free, stable and hanging state, the deformation of the heat-treated workpiece can be effectively prevented. The combined lifting appliance is simple and has high strength. It can uniformly release the quenching stress during heat treatment, reduce the cracking of the lifting appliance, extend the service life, ensure production safety, and have significant economic benefits.

The combined lifting appliance has been put into use in batches and can be used for various heat treatment operations such as carburizing, quenching, tempering, normalizing and annealing of workpieces. The lifting appliance has good flexibility, can reasonably load the furnace, greatly uses the equipment space, saves 40% of the auxiliary time of furnace loading, furnace discharging and parts loading and unloading, better adapts to the characteristics of heat treatment operation, increases the furnace loading by 3~8 times, improves the work efficiency, reduces the labor intensity of workers, and ensures the occupational health and safety of workers.