What Is Overhead Rail Shot Blasting Machine

The overhead rail shot blasting machine, also known as continuous hanging shot blasting machine, which uses a suspension chain as a workpiece carrying device. On Aug 14th 2021, QGMA GROUP successfully accepted an overhead rail shot blasting machine after the installation at the customer site in China. Let me give a detailed introduction to this equipment.

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The overhead rail shot blasting machine is a single-stroke rial continuous shot blasting equipment. It has the functions of static loading and unloading of workpieces, automatic and rapid conveying and positioning, and self-rotate and shot blasting of workpieces. The overhead rail shot blasting machine adopts conventional electrical control, and the conveying track of the workpiece adopts stepless speed regulation. It is suitable for all-round shot blasting cleaning of large quantities, cast steel, cast iron, and welded parts, and can be used for various types of hanging workpieces.

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The suspension chain can work continuously, and the weight capacity of the hooks is mostly 300 kg and 500 kg. When start the working of the shot blasting process, the workers hang a large number of workpieces onto the special tooling, then use a forklift to hang the tooling full of workpieces on the hook of the machine suspension chain.

The hooks enter the shot blasting chamber in turn for shot blasting. There is a rotation device on the top of the shot blasting chamber body of the shot blasting machine, so that the hooks that full of workpieces can rotate in the shot blasting chamber body during the shot blasting process, and clean up in all directions without dead angles. There are a number of hooks reserved outside the shot blasting chamber, which can be used to load and unload workpieces during shot blasting to improve productivity.

After the workpiece is processed, move out of the shot blasting chamber with the hooks. The next set of hooks hang the workpiece into the shot blasting chamber for processing. This type of shot blasting machine works continuously and is suitable for mass processing of all kinds of easily suspended workpieces. Such as engine cylinder heads, motor housings, gears, motorcycle engine housings, locomotive hook and tail frame components, bogie components, hardware tool housings, water pumps, etc.

The cleaning effect is particularly good. It is an ideal choice for industries such as automobiles, tractors, diesel engines, motors, valves, etc. Generally, it can be customized according to your requirements. This type of shot blasting machine adopts the suspension chain as the carrying device, so it can be used in line with the die-casting department, cleaning department, finishing department, inspection department and spraying department, etc.

Through shot blasting, not only can the rust on the surface of the workpiece be removed, the welding slag on the structural parts can be cleaned, but also the welding stress of the workpiece can be eliminated, the fatigue strength of the workpiece can be improved, and the paint film adhesion of the workpiece can be increased. The purpose of improving the surface and internal quality of the entire workpiece. It is widely used in metallurgy, petroleum, chemical, machinery and other industries.

QGMA GROUP designed a three-station step type overhead rail shot blasting machine for customers, which is mainly composed of shot blasting chamber, pneumatic opening and closing door, wheel blast turbine assembly, abrasive reclaim system, catenary conveyor (without Stage speed regulation), workpiece rotation mechanism (stepless speed regulation), dust collector system and electric control system with Omron PLC.

The blasting chamber of overhead rail shot blasting machine

What is overhead rail shot blasting machine 3The side wall of the shot blasting chamber is designed with 6 high efficiency wheel blast turbine assembly, divided into 3 stations, each station has two blasting turbines, to ensure that the cleaned workpieces are fully shot blasted. ZGMn13 wear-resistant protective plates are used for the protective plates lining inside the chamber.

The layout of the blasting turbine is dynamically simulated by the computer, and all the angles and positions of the layout are determined by the computer design. On the basis of taking care of all the workpieces that need to be cleaned, the empty throw of projectiles is minimized, thereby maximizing the utilization rate of projectiles and reducing the wear of the protective plate in the shot blasting chamber.

The hook walking through at the top of the cleaning chamber adopts a guard plate, a multi-layer anti-wear rubber plate, and the bottom layer is sealed with an impact-resistant polyurethane plate. The rubber plate on the top forms a labyrinth seal with an exquisite structure to prevent the abrasive from rebounding to the outside of the chamber. At the same time, the moving part of the catenary hook on the top of the chamber is sealed by a movable sealing plate.

At the same time, the inlet and outlet of the shot blasting chamber are sealed with wear-resistant rubber plates with elastic clamps. We also install ZGMn13 wear-resistant guard plates at the entrances and exits on both sides of the shot blasting chamber to extend the service life.

Wheel blast turbine assembly

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The wheel blast turbine assembly is composed of blast turbine, blades, abrasive distributor, control cage, side guard plate, end guard plate, top guard plate, impeller, motor, etc. This machine has 6 sets of blast turbine, with special blasting wheel structure, shot blasting specific energy can reach 250 kg/min. The blades can fast installation and disassembly; Using single disc impeller, which with good stability, concentrated shot blasting area and uniform shot blast turbine. The blades, abrasive distributor and control cage in this shot blasting machine are made of high chromium wear-resistant materials and made by a special heat treatment process, so that the weight difference of the blades is controlled within 5 grams, which greatly reduces the operating time of the shot blasting machine. Noise extends the life of wearing parts.

We also Install a limit device on the wheel blast turbine: when opening the top cover of the shot blasting machine for maintenance, ensure that the equipment cannot be started, thereby protecting the safety of maintenance personnel.

Abrasive circulating system

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During the blast process, dust, broken abrasive and other solid particles or contaminants (fines) are generated by the rust and scale removed from the workpieces. The fines are separated in the abrasive reclamation unit which is individually adjustable to the different types and sizes of abrasive.

The Abrasive reclamation unit consists of an impact separator and a cartridge filter. The impact separator removes the fines from the abrasive and serves as a certified spark extinguisher and meets all ATEX regulations.

The cartridge filter provides the necessary negative pressure to remove dust. lt can be installed separately beside the shot blast machine. The filter is automatically cleansed by compressed air pulses which are adjustable in intensity and duration. All elements of the filter unit are free from ignition sources.

Alternatively, wet filter units can be used for the necessary dust removal. This is often applied in aluminum die casting.

Abrasive circulating system can be divided into circulating system and abrasive separation system, which is composed of screw conveyor, abrasive guide pipe, bucket elevator, air wash separator, pneumatic shot gate valve, etc.

① Screw conveyor

The screw conveyor is composed of a cycloid reducer, a screw shaft (the screw blade is made of 16Mn material), a conveying cover, and a bearing with a seat. Our company has realized serialization of this component, high versatility, interchangeability, stable and reliable performance. The whole screw shaft is processed as a whole after welding, thus ensuring the coaxiality of the two ends of the screw shaft and improving the stability of operation.

② Bucket elevator

The bucket elevator consists of a cycloid reducer, upper and lower belt pulley, conveyor belts, bucket, closed barrels and tensioning devices. In order to ensure that the conveyor belt does not slip during work, the belt pulley is made into a squirrel cage type, which not only improves the friction between the lifting tape and the pulley, avoids the slipping phenomenon of the old-fashioned light pulley, but also reduces the pre-tightening force of the lifting belt.

Extend the service life of the lifting tape. At the same time, the hoist is equipped with a set of tensioning device. When the belt is loose, the belt can be tightened by adjusting the adjustment bolts on both sides of the upper part of the hoist. The lower shaft of the hoist is equipped with a pulse wheel, which can detect and track the working status of the hoist. Once the bucket elevator does not rotate or slips, the signal can be fed back to the PLC for processing in time to ensure the safe operation of the equipment.

③Air wash separator

This machine adopts advanced full curtain separator. This machine adopts advanced full curtain separator. The separator is mainly composed of a separating and conveying screw, an abrasive silo in the sorting area, and so on. Adjusting the seam between the vertical and horizontal adjustment baffles of the separator can improve the height and trajectory of the cloth layer. With the adjustment of the adjustment baffle of the separation zone, that can be obtained a good separation effect, and the separation efficiency can be as high as 99%.

Catenary conveyor

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① Catenary

Heavy-duty die-forged detachable chain, single hook load-bearing 700Kg.

②Drive device

The hoisting chain drive is a chain drive, and the required speed is obtained by the planetary reducer transmission device. The cleaning work piece hung on the anchor head hook is dragged by the drive sprocket through the chain and travels step by step along the hanging rail.

③Tightening device

It is used to compensate the manufacturing error of chain length and track length, which is beneficial to the installation of the chain and compensates the influence of the increase of the chain pitch due to wear during operation, so as to maintain the tension of the chain and eliminate the line The amount of tension that may be generated. The tensioning device of this machine relies on the gravity of the counterweight to roll the rollers on the frame of the trolley and drive the rollers to move to achieve the purpose of automatic tensioning.

Hook rotation device

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This machine with 3 station hooks shared to use the hook rotation device. The hook is stopped after entering the shot blasting chamber along the hanging rail. The cylinder drives the rotation mechanism to engage the chain with the sprocket on the hook. The hook rotation mechanism operates to drive the hook to rotate. In this way, it can not only reduce the wear of the chain, but also be suitable for the rotation and cleaning of the workpiece in the shot blasting zone.

Dust collector system

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We adopts 2-level dust collector: settling chamber and cartridge filters. Cleaning efficiency is up to 99.5%. The material of filter is from Donaldson, the effective filtration area of each filter is up to 15 ㎡. The air shock valve with timing device can clean filters regularly.

Since there is a layer of oil on the workpiece that the customer needs to clean, we add additional explosion-proof and pressure relief devices on the dust collector to ensure the safety of the dust removal system.

Electronic control system

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This machine is controlled by imported programmable controller (PLC); all other electrical components are made by domestic brand manufacturers. The whole system can be operated automatically or controlled manually.

It is equipped with a abrasive circulation system failure alarm function, and if one of the components of the system fails, the components above it will automatically stop running to prevent the abrasive from jamming.

The door of the shot blasting chamber is interlocked with the abrasive valve of the blast turbine. The door must be closed to open the abrasive valve, which not only improves the production efficiency but also prolongs the service life of the motor.

Each blast turbine is equipped with an ammeter, which can effectively reflect the working state of the shot blasting machine.

The abrasive circulation system of the entire equipment, including elevator, separators, screw conveyors, etc., uses automatic detection devices. When a certain part is not running smoothly or stuck, it can automatically alarm and notify the faulty part, so that the maintenance personnel can target maintenance.

Type of overhead rail shot blasting machine

The overhead rail shot blasting machine according to items features, size and the production capacity divided into continuing through type overhead rail shot blasting machine, step-through type overhead rail shot blasting machine, and accumulation type overhead rail shot blasting machine.
The continue through type overhead rail shot blasting machine is not only can be used with the coating line but also can use as a single machine. The continue through type as its name can working continues. When one workplace is blasting, the other one can loading and unloading the items. The machine can highly improve the working efficiency and it also can save labor and cost.

The step-through type overhead rail shot blasting machine working principle is when the one item into the blasting chamber and start to blasting, the door will be closed and the item rotary in the chamber. After blasting is completed, the door opened and the item is out of the chamber. Users can according to their item’s requirements to adjust the cleaning time to control the productivity and cleaning effect. This machine realizes a double working place for blasting and unloading items.

The accumulation type overhead rail shot blasting machine is designed according to the object items’ requirements. The users can perform intermittent work on the machine according to the situation. The hook walking trough on the shot blasting machine adopts a three-stage sealing protection method of flexible steel core rubber plate, nylon brush, and air-controlled pull cover plate, with a good sealing effect.

How to improve the performance of the overhead rail shot blasting machine?

  1. Study the working principle of the shot blasting turbines, analyze the cleaning and strengthening effects of the shot blasting turbines and calculate the theoretical data of the basic performance indicators of the shot blasting turbines.
  2. According to the actual production and processing overhead rail shot blasting machine, a three-dimensional model of its shot blasting turbines and chamber body is established to provide a basis for software analysis.
  3. Use the ADAMS simulation model to analyze the movement state of the abrasive, combine several theories of the abrasive analysis in the literature and select an appropriate method for software simulation. Considering the influence of air resistance, gravity, throwing angle and throwing distance, the impact process of the abrasive is analyzed and verified by calculation.
  4. Use ANSYS/LS-DYNA to analyze the guard plate in the blasting chamber, to get the corresponding stress diagram and maximum stress and improve the design scheme.

Nowadays, many customer chose to use the overhead rail shot blasting machine. That because this machine not only can use single, but also can working with the painting and curing oven as a production line. However, when we use the machine, it should be operated in strict accordance with the production standards. Otherwise it will not only cause damage to the equipment, but also cause physical injury to the operator.

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