The working principle, installation, maintenance and maintenance of the shot blasting machine

1. Working principle of shot blasting machine:
The shot blasting machine is the core component of the cleaning machine, and its structure is mainly composed of impeller, blade, directional sleeve, shot wheel, main shaft, cover, main shaft seat, motor and so on.
During the high-speed rotation of the impeller of the shot blasting machine, centrifugal force and wind force are generated. When the projectile flows into the shot pipe, it is accelerated and brought into the high-speed rotating shot dividing wheel. Under the action of centrifugal force, the projectiles are thrown from the shot separation wheel and through the directional sleeve window, and are continuously accelerated along the blades to be thrown out. The thrown projectiles form a flat stream, which strikes the workpiece and plays the role of cleaning and strengthening.
2. Regarding the installation, repair, maintenance and disassembly of the shot blasting machine, the details are as follows:
1. Installation steps of shot blasting machine
1. Install the shot blasting shaft and bearing on the main bearing seat
2. Install the combination disc on the spindle
3. Install the side guards and end guards on the housing
4. Install the main bearing seat on the shell of the shot blasting machine and fix it with bolts
5. Install the impeller body on the combination disc and tighten it with bolts
6. Install the blade on the impeller body
7. Install the pelletizing wheel on the main shaft and fix it with a cap nut
8. Install the directional sleeve on the shell of the shot blasting machine and press it with the pressure plate
9. Install the slide pipe
3. Precautions for the installation of shot blasting machine
1. The shot blasting wheel should be firmly installed on the wall of the chamber body, and a sealing rubber should be added between it and the chamber body.
2. When installing the bearing, pay attention to cleaning the bearing, and the operator’s hands should not contaminate the bearing.
3. An appropriate amount of grease should be filled in the bearing.
4. During normal operation, the temperature rise of the bearing shall not exceed 35℃.
5. The distance between the impeller body and the front and rear guard plates should be kept equal, and the tolerance should not exceed 2-4mm.
6. The impeller of the shot blasting machine should be in close contact with the mating surface of the combination disc and evenly tightened with screws.
7. When installing, the gap between the directional sleeve and the shot separation wheel should be kept consistent, which can reduce the friction between the shot separation wheel and the projectile, avoid the phenomenon of cracking the directional sleeve, and ensure the shot blasting efficiency.
8. When installing the blades, the weight difference of a group of eight blades should not be greater than 5g, and the weight difference of a pair of symmetrical blades should not be greater than 3g, otherwise the shot blasting machine will generate large vibration and increase noise.
9. The tension of the drive belt of the shot blasting machine should be moderately tight
Fourth, the adjustment of the directional sleeve window of the shot blasting wheel
1. The position of the directional sleeve window must be adjusted correctly before the new shot blasting machine is used, so that the thrown projectiles are thrown as much as possible on the surface of the workpiece to be cleaned, so as to ensure the cleaning effect and reduce the impact on the wear-resistant parts of the cleaning chamber. wear.
2. You can adjust the position of the orientation sleeve window according to the following steps:
Paint a piece of wood with black ink (or lay down a thick piece of paper) and place it where the workpiece is to be cleaned.
Turn on the shot blasting machine and manually add a small amount of projectiles into the shot pipe of the shot blasting machine.
Stop the blast wheel and check the position of the blast belt. If the position of the ejection belt is ahead, adjust the directional sleeve in the opposite direction along the direction of the shot blasting wheel (left-hand or right-hand rotation), and go to step 2; Orientation adjustment directional sleeve, go to step 2.
If satisfactory results are achieved, mark the position of the directional sleeve window on the shot blasting wheel shell for reference when replacing the blades, directional sleeve and shot separation wheel.
Orientation sleeve wear inspection
1. The rectangular window of the directional sleeve is very easy to wear. The wear of the directional sleeve rectangular window should be checked frequently so that the position of the directional sleeve window can be adjusted in time or the directional sleeve can be replaced.
2. If the window is worn within 10 mm, the window is worn by 5 mm, and the directional sleeve must be rotated 5 mm against the steering of the impeller along the position mark of the directional sleeve. The window is worn by another 5 mm, and the directional sleeve must be rotated 5 mm against the impeller steering along the directional sleeve position mark.
3. If the window wears more than 10mm, replace the directional sleeve
5. Inspection of wear parts of shot blasting machine
After each shift of cleaning equipment, the wear of the blast wheel wear parts should be checked. The conditions of several wear-resistant parts are described below: the blades are the parts that rotate at high speed and are most easily worn during operation, and the wear of the blades should be checked frequently. When one of the following situations occurs, the blades must be replaced in time:
The blade thickness is reduced by 4~5mm.
The blade length is reduced by 4~5mm.
The blast wheel vibrates violently.
Inspection method If the shot blasting machine is installed in the shot blasting room that the maintenance personnel can easily enter, the blades can be inspected in the shot blasting room. If it is difficult for maintenance personnel to enter the shot blasting room, they can only observe the blades outside the shot blasting room, that is, open the shell of the shot blasting machine for inspection.
Generally, when replacing the blades, all of them should be replaced.
The weight difference between the two symmetrical blades should not exceed 5g, otherwise the shot blasting machine will vibrate greatly during operation.
6. Replacement and maintenance of pilling wheel
The shot separation wheel is set in the directional sleeve of the shot blasting wheel, which is not easy to inspect directly. However, every time the blades are replaced, the pilling wheel must be removed, so it is advisable to check the wear of the pilling wheel while replacing the blades.
If the shot separation wheel is worn and continued to be used, the projectile diffusion angle will increase, which will accelerate the wear of the shot blaster guard and affect the cleaning effect.
If the outer diameter of the pelletizing wheel is worn by 10-12mm, it should be replaced
7. Replacement and maintenance of shot blasting guard plate
Wear parts such as top guard, end guard and side guard in the shot blasting wheel are worn to 1/5 of the original thickness and must be replaced immediately. Otherwise, the projectile may penetrate the blast wheel housing
8. Replacement sequence of wear parts of shot blasting machine
1. Turn off the main power.
2. Remove the slipping tube.
3. Use a socket wrench to remove the fixing nut (rotate left and right), tap the pilling wheel lightly, and remove it after loosening.
Remove the orientation sleeve.
4. Tap the head of the leaf with a wooden hob to remove the leaf. (Remove 6 to 8 hexagonal screws in the fixed impeller body hidden behind the blade in a counterclockwise direction, and the impeller body can be removed)
5. Check (and replace) the wear parts.
6. Return to install the shot blaster in the order of disassembly
9. Common faults and troubleshooting methods of shot blasting machine
Poor cleaning effect Insufficient supply of projectiles, increase projectiles.
The projection direction of the shot blasting machine is incorrect, adjust the position of the directional sleeve window.
The shot blasting machine vibrates greatly, the blades are seriously worn, the rotation is unbalanced, and the blades are replaced.
The impeller is seriously worn, replace the impeller.
The main bearing seat is not filled with grease in time, and the bearing is burned out. Replace the main bearing housing or bearing (its fit is a clearance fit)
There is abnormal noise in the shot blasting wheel The projectile does not meet the requirements, resulting in sand inclusion between the shot blasting wheel and the directional sleeve.
The separation screen of the separator is too large or damaged, and large particles enter the shot blasting wheel. Open the blast wheel and check for removal.
The inner guard plate of the shot blasting machine is loose and rubs against the impeller or blade, adjust the guard plate.
Due to vibration, the bolts that combine the shot blasting wheel with the chamber body are loose, and the shot blasting wheel assembly must be adjusted and the bolts tightened.
10. Precautions for debugging of shot blasting machine
10.1. Check whether the impeller is installed in the correct position.
10.2. Check the tension of the blast wheel belt and make necessary adjustments.
10.3. Check whether the limit switch on the cover is working normally.
10.4. Remove all foreign objects on the shot blasting device during the installation process, such as bolts, nuts, washers, etc., which can easily fall into the machine or mix into the shot material, resulting in premature damage to the machine. Once foreign objects are found, they should be removed immediately.
10.5. Debugging of shot blasting machine
After the final installation and positioning of the equipment, the user should conduct fine debugging of the equipment according to the specific working conditions.
Turn the directional sleeve to adjust the direction of the shot jet within the projection range. However, too much left or right deflection of the jet will reduce the projectile power and accelerate the abrasion of the radial shield.
An optimal projectile mode can be debugged as follows.
10.5.1. Place a lightly corroded or painted steel plate in the shot blasting area.
10.5.2. Start the shot blasting machine. The motor accelerates to the proper speed.
10.5.3. Use the control valve (manually) to open the shot blasting gate. After about 5 seconds, the shot material is sent to the impeller, and the metal rust on the lightly corroded steel plate is removed.
10.5.4. Determination of projectile position
Use a 19MM adjustable wrench to loosen the three hexagonal bolts on the pressure plate until the directional sleeve can be turned by hand, and then tighten the directional sleeve.
10.5.5. Prepare a new projection map to test the best settings.
The procedure described in Sections 10.5.3 to 10.5.5 is repeated as many times as possible until the optimal projectile position is obtained.
11. Precautions for the use of shot blasting machine
Use of the new blast wheel
The new shot blasting machine should be tested with no load for 2-3 hours before use.
If strong vibration or noise is found during use, the test drive should be stopped immediately. Open the blast wheel front cover.
Check: whether the blades, directional sleeves and pelletizing wheels are damaged; whether the weight of the blades is too different; whether there are sundries in the blast wheel.
Before opening the end cover of the blast wheel, the main power supply of the cleaning equipment should be cut off, and the label should be listed.  Do not open the end cover when the shot blasting wheel has not completely stopped rotating
12. Selection of shot blaster projectiles
According to the particle shape of the projectile material, it is divided into three basic shapes: round, angular and cylindrical.
The projectile used for shot blasting is preferably round, followed by cylindrical; when the metal surface is pretreated for shot blasting, rust removal and erosion by painting, the angular shape with slightly higher hardness is used; the metal surface is shot peened and formed. , it is best to use a circular shape.
The round shapes are: white cast iron shot, decarburized malleable cast iron shot, malleable cast iron shot, cast steel shot.
The angular ones are: white cast iron sand, cast steel sand.
Cylindrical are: steel wire cut shot.
Projectile common sense:
The new cylindrical and angular projectiles have sharp edges and corners that gradually become rounded after repeated use and wear.
Cast steel shot (HRC40~45) and steel wire cutting (HRC35~40) will work hardening automatically in the process of repeatedly hitting the workpiece, which can be increased to HRC42~46 after 40 hours of work. After 300 hours of work, it can be increased to HRC48-50. When cleaning sand, the hardness of the projectile is too high, and when it hits the surface of the casting, the projectile is easy to break, especially the white cast iron shot and white cast iron sand, which have poor reusability. When the hardness of the projectile is too low, the projectile is easy to deform when it hits, especially the decarburized malleable iron shot, which absorbs energy when it deforms, and the cleaning and surface strengthening effects are not ideal. Only when the hardness is moderate, especially cast steel shot, cast steel sand, steel wire cut shot, can not only prolong the service life of the projectile, but also achieve the ideal cleaning and strengthening effect.
Particle size classification of projectiles
The classification of the round and angular projectiles in the projectile material is determined according to the screen size after screening, which is one size smaller than the screen size. The particle size of wire cut shot is determined according to its diameter. The diameter of the projectile should not be too small nor too large. If the diameter is too small, the impact force is too small, and the sand cleaning and strengthening efficiency is low; if the diameter is too large, the number of particles sprayed on the surface of the workpiece per unit time will be less, which will also reduce the efficiency and increase the roughness of the workpiece surface. The diameter of the general projectile is in the range of 0.8 to 1.5 mm. Larger workpieces generally use larger projectiles (2.0 to 4.0), and small workpieces generally use smaller ones (0.5 to 1.0). Please refer to the following table for specific selection:
Cast steel shot Cast steel grit Steel wire cut shot Use
SS-3.4 SG-2.0 GW-3.0 Large-scale cast iron, cast steel, malleable iron castings, large-scale casting heat-treated parts, etc. Sand cleaning and rust removal.
SS-2.8 SG-1.7 GW-2.5
SS-1.4 SG-1.4 CW-1.5 Large and medium-sized cast iron, cast steel, malleable iron castings, billets, forgings, heat-treated parts and other sand cleaning and rust removal.
SS-1.2 SG-1.2 CW-1.2
SS-1.0 SG-1.0 CW-1.0 Small and medium-sized cast iron, cast steel, malleable iron castings, small and medium-sized forgings, heat-treated parts rust removal, shot peening, shaft and roller erosion.
SS-0.8 SG-0.7 CW-0.8
SS-0.6 SG-0.4 CW-0.6 Small-sized cast iron, cast steel, heat-treated parts, copper, aluminum alloy castings, steel pipes, steel plates, etc. Sand cleaning, rust removal, pretreatment before electroplating, shot peening, shaft and roller erosion.
SS-0.4 SG-0.3 CW-0.4 Derusting of copper, aluminum alloy castings, thin plates, stainless steel strips, shot peening, and roller erosion.
13. Daily maintenance of shot blasting machine
Daily inspection
Manual inspection
Check whether all the screws and clamping connection parts (especially the blade fasteners) are tightened, and whether the directional sleeve, feeding pipe, pelletizing wheel, machine cover, fastening screws, etc. are loose, if there is looseness, apply 19 mm and 24mm wrench to tighten.
Check whether the bearing is overheated. If it is overheated, the bearing should be refilled with lubricating oil.
For the motor direct-pull shot blasting machine, check whether there are projectiles in the long groove on the side of the casing (the side where the motor is installed). If there are projectiles, use compressed air to remove them.
Sound inspection when the shot blasting wheel is idling (no projectiles), if any noise is found in operation, it may be excessive wear and tear of machine parts. At this time, the blades and guide wheels should be visually inspected immediately. If it is found that the noise is coming from the bearing part, preventive repairs should be carried out immediately.
Refueling of blast wheel bearings
Each axle seat has three spherical lubricating oil nipples, and the bearings are lubricated through the oiling nipple in the middle. Fill the labyrinth seal with oil through the two filler nozzles on both sides.
About 35 grams of grease should be added to each bearing, and 3# lithium-based grease must be used.
Visual inspection of wearing parts
Compared to all other wearing parts, blasting blades, splitter wheels and directional sleeves are particularly vulnerable due to their action inside the machine. Therefore, regular inspections of these parts should be ensured. All other wearing parts should also be checked at the same time.
Blast Wheel Disassembly Procedure
Open the maintenance window of the blast wheel, which can only be used by maintenance personnel to observe the blades. Slowly turn the impeller to check each blade for wear. The blade fasteners can be removed first, and then the blades can be pulled out from the impeller body groove. It is not always easy to separate the blades from their fasteners, and the shot and rust may enter the gap between the blade and the groove. Clogged vanes and vane fasteners. Under normal circumstances, the fasteners can be removed after a few taps with a hammer, and the blades can also be pulled out from the impeller body groove.
※If it is difficult for maintenance personnel to enter the shot blasting room, they can only observe the blades outside the shot blasting room. That is, open the shell of the shot blasting machine for inspection. Loosen the nut with a wrench first, and the guard plate bracket can be released from the fastener and removed together with the compression screw. In this way, the radial shield can be withdrawn from the housing. The maintenance window allows maintenance personnel to visually observe the blades, slowly rotate the impeller, and observe the wear of each impeller.
Replace the blades
If there is groove-like wear on the blade surface, it should be turned over immediately, and then replaced with a new blade.
Because: the most intense wear occurs in the outward part of the blade (shot ejection area) and the inward part (shot inhalation area) is subject to very little wear. By changing the inner and outer end faces of the blade, the part of the blade with less wear degree can be used as the throwing area. During subsequent maintenance, the blades can also be turned over, so that the overturned blades can be reused. In this way, each blade can be used four times with uniform wear, after which the old blade must be replaced.
When replacing old blades, a complete set of blades of even weight should be replaced at the same time. The blades are inspected at the factory to ensure that the blades are all of the same weight and are packaged as a set. The maximum weight error of each blade belonging to the same set shall not exceed five grams. Replacing different sets of blades is discouraged because different sets of blades are not guaranteed to have the same weight. Start the shot blasting machine to make it idle, that is, without shot blasting, and then stop, and pay attention to whether there is any noise in the machine during this process.
Disassembly of pill feeding tube, pill dividing wheel and directional sleeve.
Use a wrench to remove the two hexagonal nuts from the splint, and then unscrew the splint to pull out the pellet guide tube.
Hold the impeller in place with a bar inserted between the blades (find a support point on the casing). Then use a wrench to unscrew the socket head cap screw from the impeller shaft,

Then take out the pilling wheel. The installation of the pelletizing wheel can be carried out according to the following procedures, first install the pelletizing wheel into the groove of the impeller shaft, and then screw the screw into the impeller shaft. The maximum torque applied to the screw with a dynamometer wrench reaches Mdmax=100Nm. Before removing the directional sleeve, mark its original position on the scale of the casing. Doing so makes installation easy and avoids later adjustments.
Pilling wheel inspection and replacement
Under the centrifugal force of the pelletizing wheel, the pellets added along the axial direction are accelerated. The pellets can be accurately and quantitatively sent to the blade through the eight pelletizing grooves on the pelletizing wheel. Excessive wear of the shot distribution slot ~ (expansion of the shot distribution slot ~) can damage the feeder and cause damage to other parts. If it is observed that the pelletizing notch has expanded, the pelletizing wheel should be replaced immediately.
Inspection and replacement of impeller body
Conventionally, the service life of the impeller body should be two to three times the life of the above-mentioned parts. The impeller body is dynamically balanced. However, under uneven wear, the balance will also be lost after working for a long time. In order to observe whether the balance of the impeller body has been lost, the blades can be removed, and then the impeller can be idling. If the guide wheel is found to be running unevenly, it should be replaced immediately.

Post time: Apr-19-2022