Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T 7679-95
Screw Conveyor
1995-06-16 Issued
Ministry of Machinery Industry of the People's Republic of China
1996-07-01 Implementation
Mechanical Industry Standard of the People's Republic of China
Screw Conveyor
Subject Content and Scope of Application
JB/T 7679--95
This standard specifies the basic parameters, basic calculation principles, technical requirements, test methods, inspection rules, marking, packaging and storage and transportation of screw conveyors.
This standard applies to screw conveyors that continuously and evenly convey loose materials in horizontal and slightly inclined (less than 15°). The working environment temperature is 20～+40℃, and the conveying material temperature is -20～+80℃. 2 Reference standards
GB 3768
GB8923
GB9286
GB 9439
GB 11352
GB/T12469
GB/T13306
GB/T13384
Determination of sound power level of noise source-Simplified methodSurface rust grade and rust removal grade of steel before paintingScratching test of paint and varnish film
Gray cast iron parts
Casting carbon steel parts for general engineering
Welding quality assuranceRequirements and defect classification labels for steel fusion welded joints
General technical conditions for packaging of electromechanical products
3 Basic parameters and basic principles of calculation
3.1 Basic parameters and dimensions
The basic parameters and dimensions of screw conveyors shall comply with the requirements in Figure 1 and Table 1. 4
Approved by the Ministry of Machinery Industry on June 16, 1995
Implemented on July 1, 1996
LS1000
LS1250
Nominal screw diameter!
JB/T 7679-
Note: The length L of the screw conveyor is increased by 500mm from the minimum length3.2 Model
-grade.
Length of screw conveyor, m
Nominal screw diameter, mm
Code of screw conveyor
Marking example:
The screw conveyor with a nominal screw diameter of 400mm and a conveyor length of 12m is marked as: Screw conveyor LS400-12JB/T7679
3.3 The conveying capacity and driving power of the screw conveyor shall be calculated according to Appendix A (Supplement). 4 Technical requirements
4.1 General technical requirements
Nominal spindle speed
4.1.1 The screw conveyor shall comply with the requirements of this standard and shall be manufactured according to the drawings and technical documents approved by the prescribed procedures. 4.1.2 Castings shall comply with the technical requirements of GB9439 and GB11352. 4.1.3 Welded parts shall comply with the requirements of defect classification sub-levels in GB/T12469. 4.1.4 All outsourced and purchased parts shall have a certificate of conformity and shall be assembled only after passing the inspection of the inspection department. 4.1.5 Before painting, the steel surface shall be derusted and shall meet the requirements of Sa2 or St3 in GB8923. 71
4.1.6 Painted parts shall be coated with one layer of primer and two layers of topcoat. The total thickness of the paint film is 50~100um, and the adhesion of the paint film shall meet the requirements of Level 2 in GB9286.
4.2 Technical requirements for the whole machine
The structure of the screw conveyor shall ensure:
JB/T7679-
When disassembling the screw, the drive device does not need to be moved or disassembled; when disassembling the intermediate bearing, the screw does not need to be moved or disassembled; the intermediate bearing can be lubricated without disassembling the trough and cover plate. The cross-sectional area of the intermediate bearing under the geometric axis of the spiral trough in the screw conveyor trough shall not exceed 25% of the effective area of the trough under the geometric axis of the spiral.
4.2.3 The outer diameter tolerance of the screw shall comply with the provisions of Table 2. Table 2
Nominal diameter of the screw
The pitch tolerance of the screw shall comply with the provisions of Table 3. Pitch
100~250
315~500
560~630
The clearance between the outer diameter of the screw and the trough shall not exceed the provisions of Table 4, and its minimum clearance shall not be less than 50% of the nominal clearance. Table 4
Nominal screw diameter
Nominal clearance
When the screw conveyor is running idle, when the conveyor length is 20m, the conveyor shaft torque shall not exceed the provisions of Table 5. Table 5
Nominal screw diameter
After the screw conveyor runs idle for 2h, the bearing temperature rise shall be less than 20℃. The noise of the screw conveyor running idle shall be less than 85dB. 800
Before the first overhaul of the screw conveyor, the cumulative working time shall not be less than 8500h. Test method
Measurement of the gap between the outer diameter of the spiral and the material groove
Use a stop gauge to measure the gap between the left and right points of the outer circle of the spiral and the lowest point and the material groove. Each solid spiral should be measured at two locations. 5.2 Determination of spindle torque
Use a torque meter to measure the torque at the spindle.
5.3 Determination of noise
Noise is measured using a sound level meter (A gear) according to GB3768. 5.4 Paint film measurement
The paint film thickness is measured using a magnetic thickness gauge, and the paint film adhesion is tested by a cross-cut test according to GB9286. 6
Inspection rules
6.1 Each product can only be shipped after passing the manufacturer's technical inspection. When leaving the factory, it should be accompanied by documents proving that the product quality is qualified. 3
6.2 Factory inspection
6.2.1 Item
Inspection requirements of Article 4.14.2.8 of this standard.
6.2.2 Quantity
JB/T 7679-95
5% of the product batch shall be sampled for testing, but at least one unit shall be taken. If the sample fails to meet the standard, double the sample shall be taken for testing. If one unit fails to meet the standard, the batch shall be deemed as unqualified.
6.3 The cumulative working time of the screw conveyor before the first overhaul shall be measured at the site of use. 7 Marking, packaging and storage and transportation
7.1 The screw conveyor shall be equipped with a label in a conspicuous position on the head, and the label shall comply with the provisions of GB/T13306. The content of the label is as follows: a.
Product name;
Product model;
Spindle speed and machine weight;
Factory date and number;
Manufacturer name.
7.2 The packaging, reinforcement, rainproof and moisture-proof requirements of the screw conveyor parts shall comply with the requirements of GB/T13384. 7.3 The screw conveyor should be shipped with the following documents: a.
Product certificate:
Product instruction manual:
Packing list.
7.4 The screw conveyor should be stored in a well-ventilated and rainproof warehouse to avoid rust and damage. 7.5 Provided that the user complies with the regulations for storage, transportation, installation and use of the product, within 18 months from the date of shipment, of which the use time in a single shift (8h/day) shall not exceed 12 months, if the product is damaged or fails to work properly due to poor manufacturing quality, the manufacturer shall repair or replace parts for the user free of charge.
AI Scope of application
JB/T 7679-95
Appendix A
Basic principles for calculation of screw conveyors
(Supplement)
This appendix includes the provisions for unified calculation of screw conveyors, which are applicable to horizontal or slightly inclined (less than 15°) screw conveyors that continuously and evenly transport loose materials.
This appendix does not apply to the following special screw conveyors used in special occasions: a
Discharging screw conveyor:
Batching screw conveyor;
Mixing screw conveyor:
Wet screw conveyor
Screw conveyor with an inclination angle greater than 15°: Vertical screw conveyor.
A2 Concept
The screw conveyor is a continuous conveyor, which consists of a spiral blade fixed on a pipe shaft and a fixed trough. The shaft with the spiral blade rotates in the fixed trough.
The bulk material fed into the trough rotates together with the spiral blade in the trough, but is prevented by the friction resistance on the trough wall. During operation, the screw pushes the bulk material to move axially. The bulk material can fall from a suitable opening at the bottom of the trough or be discharged from the end of the trough. A3 Basic principles and accuracy of calculation
The driving power required for a screw conveyor is related to its conveying capacity, but it is also related to the working conditions and the nature and structure of the conveyed material and the most important calculation parameters considered in this standard. This standard proposes a relatively simple calculation method. Although it only achieves limited accuracy, it can fully meet the requirements in most cases. A4 Symbols and units
A: Axial projection area of the screw, m\; D: Nominal diameter of the screw conveyor, mFH: Main resistance, N;
Fn: Additional resistance. N;
Fst: Inclination resistance, N;
: Gravitational acceleration, m/s\;
H: Lifting height + m;
Im: Mass conveying capacity, t/h
I: Volume conveying capacity, m\/h;
L: Length of screw conveyor, m ：
n：screw conveyor speed, r/min；
P：total driving power, kW；
PH：material running power, kW；
P：no-load power, kW；
F'st：tilt power.kW；
S：screw pitch.m：
t：screw conveyor conveying speed.m/s
in：operating resistance coefficient；
in：filling coefficient；
o：bulk density, t/m\。
A5Calculation of the conveying capacity of screw conveyor
B/T 767995
The initial data for calculating the volume and mass conveying capacity of screw conveyor are the screw axial projection area A of the conveyor, the conveying speed and the filling coefficient of the screw conveyor trough. From AD and =S, we can conclude that:
Iv = 60 ×
and Im=p Iv=60×
I= 47 × pD'S n
. (A2)
where the mass conveying capacity I... is the maximum mass throughput of the screw conveyor under rated conditions. This throughput depends on the size of the filling factor. This value cannot be too large, because when the filling is too full, there is a non-negligible difference between the theoretical conveying speed used in the formula and the actual conveying speed. In addition, when the filling factor is large, the intermediate bearing of the long screw conveyor is prone to failure. The filling factor depends on the friction properties of the conveyed material and its adhesion properties, the pitch and the inclination of the center line of the screw conveyor. Generally, the value is:
for materials that are easy to flow and have almost no abrasion, such as flour and cereals, is taken as 0.45; for bulk materials that are slightly abrasive and in granular or small pieces (such as salt, sand, coal), is taken as 0.33; for bulk materials that are very abrasive and corrosive and have a high bulk density (such as slag, gravel, ore), is taken as 0.15. The value should be reduced in the following cases:
when the pitch is particularly large, it is reduced by 10%;
for each degree of inclination of the screw conveyor axis, it is reduced by about 2%; if it is necessary to load at the intermediate support, it is reduced by 10%. c.
The circumferential speed of the screw conveyor is not allowed to be too large, otherwise the conveyed material will be subjected to strong centrifugal action, affecting the conveying process. According to this principle, the maximum speed nmx depends on the screw diameter D, and the recommended value can be selected according to Table A1. In addition, Table A1 also includes the recommended pitch value S that matches each screw diameter. Table A1
Screw diameter D
Recommended pitch S
Recommended screw conveyor speed max
JB/T 7679 -- 95
The minimum screw diameter of the screw conveyor required depends on the required production rate of the conveyed material and the size of the bulk material. For bulk materials: The screw diameter D should be at least 10 times the maximum side length α of the particle. If the content of large particles is small, a smaller screw diameter is also allowed. But at least D ≥ 4αmx
A6 Screw conveyor movement resistance
Due to the rotation of the conveying screw and the forward movement of the material, a number of resistances against movement are generated, which are composed of the following resistances: Material running resistance FH;
No-load running resistance FN
Tilt resistance F
The above three resistances are all the resistances that the screw conveyor drive must overcome in order to overcome friction, tilt and the movement of the material at the loading point.
Tilt resistance does not exist in all devices, it is a function of the line inclination. Among all resistances, only tilt resistance can be accurately calculated.
A7 Screw conveyor driving power
Screw conveyor driving power:
P = PH + Pn + Pst
Where: PH
Power required when materials are running:
Pn—driving power of screw conveyor when no-load operation; Pst
Tilt power.
A7.1 Power required for material operation PH
For a screw conveyor with a length of L, its power PH is the product of the conveying volume Im, length L and running resistance coefficient In: 3600/g = lnLd
（A4）
The coefficient is specific to each conveying material, usually the In value is between 2 and 4. The In values of some bulk materials often conveyed by screw conveyors can be selected according to Table A2.
Table A2 Bulk density β and running resistance coefficient of several bulk materials Material category
Good fluidity, slightly abrasive
Powdered and fine-grained materials
Aluminum sulfate
Material name
Baking soda (sodium bicarbonate)
Bauxite powder (dry)
Lan Ma beans (whole grains)
Borax (fine grains)
Coffee ( Roasted beans)
Cottonseed (dry, dust-free)
Fuller's earth (burned)
Material categories
Good-flowing, slightly abrasive
powders and granules
Medium- and poor-flowing
slightly abrasive
powders and granules
, and slightly abrasive
granular and lumpy materials
JB/T 7679—95
Continued Table A2
Material Name
Crushed Limestone
Sorghum (Grain)
Sorghum Flour
Phosphate Fertilizer
Rice (Bran Removed)
Sunflower Seed
Urea (Small Particles)
Wheat, Rye
Wheat (Sprout)
Anthracite (Piece Size Less Than 12mm）
Graphite flakes
Aluminum hydroxide
Ammonium nitrate
Ammonium sulfate
Barley flour (sprout)
Bran, bran
Calcium phosphate
Soda
Caustic soda flakes
Anthracite (washed crushed coal)
Coffee (instant)
0.45(0.5)N;
Fst: tilt resistance, N;
: acceleration due to gravity, m/s\;
H: lifting height +m;
Im: mass conveying capacity, t/h
I: volume conveying capacity, m\/h;
L: screw conveyor length, m:
n: screw conveyor speed, r/min;
P: total driving power, kW:
PH: material operating power, kW;
P: no-load power, kW;
F'st: tilt power.kW;
S: pitch.m:
t: conveying speed of screw conveyor.m/s
in: operating resistance coefficient;
m: filling coefficient;
o: stacking density, t/m\.
A5 Calculation of the conveying capacity of screw conveyor
B/T 767995
The initial data for calculating the volume and mass conveying capacity of screw conveyor are the axial projection area A of the screw conveyor, the conveying speed and the filling coefficient of the screw conveyor trough. From AD and =S, it can be concluded that:
Iv = 60 ×
and Im=p Iv=60×
I= 47 × pD'S n
. (A2)
The mass conveying capacity I... is the maximum value of the mass throughput completed by the screw conveyor under rated working conditions. The throughput depends on the size of the filling coefficient. This value is not allowed to be too large, because when the filling is too full, there is a non-negligible difference between the theoretical conveying speed used in the formula and the actual conveying speed. In addition, when the filling coefficient is large, the intermediate bearing of the long screw conveyor is prone to failure. The filling coefficient depends on the friction and adhesion properties of the conveyed material, the pitch and the inclination of the center line of the screw conveyor. Generally, it is taken as follows:
For materials that are easy to flow and have almost no abrasion, such as flour and cereals, take = 0.45; for bulk materials that are slightly abrasive and granular to small pieces (such as salt, sand, coal), take = 0.33; for bulk materials that are very abrasive and corrosive and have a high bulk density (such as slag, gravel, ore), take = 0.15. The value should be reduced in the following cases:
When the pitch is particularly large, it is reduced by 10%;
The screw conveyor axis is reduced by about 2% for each degree of inclination: If it is necessary to load at the intermediate support, it is reduced by 10%. c.
The circumferential speed of the screw conveyor is not allowed to be too large, otherwise the conveyed material will be subjected to strong centrifugal action, which will affect the conveying process. According to this principle, the maximum speed nmx depends on the screw diameter D, and the recommended value can be selected according to Table A1. In addition, Table A1 also includes the recommended pitch values S for each screw diameter. Table A1
Screw diameter D
Recommended pitch S
Recommended screw conveyor speed max
JB/T 7679 -- 95
The minimum screw diameter of the screw conveyor required depends on the required production rate of the conveyed material and the size of the bulk material. For bulk materials: The screw diameter D should be at least 10 times the maximum side length α of the particle. If the content of large particles is small, a smaller screw diameter is also allowed. But at least D≥4αmx
A6 Screw conveyor movement resistance
Due to the rotation of the conveying screw and the forward movement of the material, a number of resistances against movement are generated, which are composed of the following resistances: material running resistance FH;
No-load running resistance FN
Tilt resistance F
The above three resistances are all the resistances that the screw conveyor drive device must overcome in order to overcome friction, tilt and the movement of materials at the loading point.
Tilt resistance does not exist in all devices, it is a function of the line tilt. Among all resistances, only the tilt resistance can be accurately calculated.
A7 Screw conveyor driving power
Screw conveyor driving power:
P = PH + Pn + Pst
Where: PH
The power required when the material is running:wwW.bzxz.Net
Pn—driving power of the screw conveyor when it is running without load; Pst
Tilt power.
A7.1 Power PH required for material operation
For a screw conveyor with a length of L, the power PH is the product of the conveying volume Im, the length L and the running resistance coefficient λ: 3600/g = lnLd
(A4)
The coefficient is specific to each conveyed material. Usually, the λ value is between 2 and 4. For several bulk materials that are often conveyed by screw conveyors, the λ values can be selected by referring to Table A2.
Table A2 Bulk density β and running resistance coefficient λ for several bulk materials Material category
Good fluidity, slightly abrasive
powdered and fine-grained materials
Aluminum sulfate
Material name
Baking soda (sodium bicarbonate)
Bauxite powder (dry)
Lan Ma beans (whole grains)
Borax (fine grains)
Coffee ( Roasted beans)
Cottonseed (dry, dust-free)
Fuller's earth (burned)
Material categories
Good-flowing, slightly abrasive
powders and granules
Medium- and poor-flowing
slightly abrasive
powders and granules
, and slightly abrasive
granular and lumpy materials
JB/T 7679—95
Continued Table A2
Material Name
Crushed Limestone
Sorghum (Grain)
Sorghum Flour
Phosphate Fertilizer
Rice (Bran Removed)
Sunflower Seed
Urea (Small Particles)
Wheat, Rye
Wheat (Sprout)
Anthracite (Piece Size Less Than 12mm）
Graphite flakes
Aluminum hydroxide
Ammonium nitrate
Ammonium sulfate
Barley flour (sprout)
Bran, bran
Calcium phosphate
Soda
Caustic soda flakes
Anthracite (washed crushed coal)
Coffee (instant)
0.45(0.5)N;
Fst: tilt resistance, N;
: acceleration due to gravity, m/s\;
H: lifting height +m;
Im: mass conveying capacity, t/h
I: volume conveying capacity, m\/h;
L: screw conveyor length, m:
n: screw conveyor speed, r/min;
P: total driving power, kW:
PH: material operating power, kW;
P: no-load power, kW;
F'st: tilt power.kW;
S: pitch.m:
t: conveying speed of screw conveyor.m/s
in: operating resistance coefficient;
m: filling coefficient;
o: stacking density, t/m\.
A5 Calculation of the conveying capacity of screw conveyor
B/T 767995
The initial data for calculating the volume and mass conveying capacity of screw conveyor are the axial projection area A of the screw conveyor, the conveying speed and the filling coefficient of the screw conveyor trough. From AD and =S, it can be concluded that:
Iv = 60 ×
and Im=p Iv=60×
I= 47 × pD'S n
. (A2)
The mass conveying capacity I... is the maximum value of the mass throughput completed by the screw conveyor under rated working conditions. The throughput depends on the size of the filling coefficient. This value is not allowed to be too large, because when the filling is too full, there is a non-negligible difference between the theoretical conveying speed used in the formula and the actual conveying speed. In addition, when the filling coefficient is large, the intermediate bearing of the long screw conveyor is prone to failure. The filling coefficient depends on the friction and adhesion properties of the conveyed material, the pitch and the inclination of the center line of the screw conveyor. Generally, it is taken as follows:
For materials that are easy to flow and have almost no abrasion, such as flour and cereals, take = 0.45; for bulk materials that are slightly abrasive and granular to small pieces (such as salt, sand, coal), take = 0.33; for bulk materials that are very abrasive and corrosive and have a high bulk density (such as slag, gravel, ore), take = 0.15. The value should be reduced in the following cases:
When the pitch is particularly large, it is reduced by 10%;
The screw conveyor axis is reduced by about 2% for each degree of inclination: If it is necessary to load at the intermediate support, it is reduced by 10%. c.
The circumferential speed of the screw conveyor is not allowed to be too large, otherwise the conveyed material will be subjected to strong centrifugal action, which will affect the conveying process. According to this principle, the maximum speed nmx depends on the screw diameter D, and the recommended value can be selected according to Table A1. In addition, Table A1 also includes the recommended pitch values S for each screw diameter. Table A1
Screw diameter D
Recommended pitch S
Recommended screw conveyor speed max
JB/T 7679 -- 95
The minimum screw diameter of the screw conveyor required depends on the required production rate of the conveyed material and the size of the bulk material. For bulk materials: The screw diameter D should be at least 10 times the maximum side length α of the particle. If the content of large particles is small, a smaller screw diameter is also allowed. But at least D≥4αmx
A6 Screw conveyor movement resistance
Due to the rotation of the conveying screw and the forward movement of the material, a number of resistances against movement are generated, which are composed of the following resistances: material running resistance FH;
No-load running resistance FN
Tilt resistance F
The above three resistances are all the resistances that the screw conveyor drive device must overcome in order to overcome friction, tilt and the movement of materials at the loading point.
Tilt resistance does not exist in all devices, it is a function of the line tilt. Among all resistances, only the tilt resistance can be accurately calculated.
A7 Screw conveyor driving power
Screw conveyor driving power:
P = PH + Pn + Pst
Where: PH
The power required when the material is running:
Pn—driving power of the screw conveyor when it is running without load; Pst
Tilt power.
A7.1 Power PH required for material operation
For a screw conveyor with a length of L, the power PH is the product of the conveying volume Im, the length L and the running resistance coefficient λ: 3600/g = lnLd
(A4)
The coefficient is specific to each conveyed material. Usually, the λ value is between 2 and 4. For several bulk materials that are often conveyed by screw conveyors, the λ values can be selected by referring to Table A2.
Table A2 Bulk density β and running resistance coefficient λ for several bulk materials Material category
Good fluidity, slightly abrasive
powdered and fine-grained materials
Aluminum sulfate
Material name
Baking soda (sodium bicarbonate)
Bauxite powder (dry)
Lan Ma beans (whole grains)
Borax (fine grains)
Coffee ( Roasted beans)
Cottonseed (dry, dust-free)
Fuller's earth (burned)
Material categories
Good-flowing, slightly abrasive
powders and granules
Medium- and poor-flowing
slightly abrasive
powders and granules
, and slightly abrasive
granular and lumpy materials
JB/T 7679—95
Continued Table A2
Material Name
Crushed Limestone
Sorghum (Grain)
Sorghum Flour
Phosphate Fertilizer
Rice (Bran Removed)
Sunflower Seed
Urea (Small Particles)
Wheat, Rye
Wheat (Sprout)
Anthracite (Piece Size Less Than 12mm）
Graphite flakes
Aluminum hydroxide
Ammonium nitrate
Ammonium sulfate
Barley flour (sprout)
Bran, bran
Calcium phosphate
Soda
Caustic soda flakes
Anthracite (washed crushed coal)
Coffee (instant)
0.45(0.5)
The circumferential speed of the screw conveyor is not allowed to be too high, otherwise the conveyed material will be subjected to strong centrifugal action, which will affect the conveying process. Based on this principle, the maximum speed nmx depends on the screw diameter D, and the recommended value can be selected according to Table A1. In addition, Table A1 also includes the recommended pitch value S that matches each screw diameter. Table A1
Screw diameter D
Recommended pitch S
Recommended screw conveyor speed max
JB/T 7679 -- 95
The minimum screw diameter of the required screw conveyor depends on the required production rate of the conveyed material and the size of the bulk material. For bulk materials: the screw diameter D should be at least 10 times the maximum side length α of the particle. If the content of large particles is small, a smaller screw diameter is also allowed. But at least D≥4αmx
A6 Screw conveyor movement resistance
Due to the rotation of the conveying screw and the forward movement of the material, a number of resistances against movement are generated, which are composed of the following resistances: material running resistance FH;
No-load running resistance FN
Tilt resistance F
The above three resistances are all the resistances that the screw conveyor drive device must overcome in order to overcome friction, tilt and the movement of materials at the loading point.
Tilt resistance does not exist in all devices, it is a function of the line tilt. Among all resistances, only the tilt resistance can be accurately calculated.
A7 Screw conveyor driving power
Screw conveyor driving power:
P = PH + Pn + Pst
Where: PH
The power required when the material is running:
Pn—driving power of the screw conveyor when it is running without load; Pst
Tilt power.
A7.1 Power PH required for material operation
For a screw conveyor with a length of L, the power PH is the product of the conveying volume Im, the length L and the running resistance coefficient λ: 3600/g = lnLd
(A4)
The coefficient is specific to each conveyed material. Usually, the λ value is between 2 and 4. For several bulk materials that are often conveyed by screw conveyors, the λ values can be selected by referring to Table A2.
Table A2 Bulk density β and running resistance coefficient λ for several bulk materials Material category
Good fluidity, slightly abrasive
powdered and fine-grained materials
Aluminum sulfate
Material name
Baking soda (sodium bicarbonate)
Bauxite powder (dry)
Lan Ma beans (whole grains)
Borax (fine grains)
Coffee ( Roasted beans)
Cottonseed (dry, dust-free)
Fuller's earth (burned)
Material categories
Good-flowing, slightly abrasive
powders and granules
Medium- and poor-flowing
slightly abrasive
powders and granules
, and slightly abrasive
granular and lumpy materials
JB/T 7679—95
Continued Table A2
Material Name
Crushed Limestone
Sorghum (Grain)
Sorghum Flour
Phosphate Fertilizer
Rice (Bran Removed)
Sunflower Seed
Urea (Small Particles)
Wheat, Rye
Wheat (Sprout)
Anthracite (Piece Size Less Than 12mm）
Graphite flakes
Aluminum hydroxide
Ammonium nitrate
Ammonium sulfate
Barley flour (sprout)
Bran, bran
Calcium phosphate
Soda
Caustic soda flakes
Anthracite (washed crushed coal)
Coffee (instant)
0.45(0.5)
The circumferential speed of the screw conveyor is not allowed to be too high, otherwise the conveyed material will be subjected to strong centrifugal action, which will affect the conveying process. Based on this principle, the maximum speed nmx depends on the screw diameter D, and the recommended value can be selected according to Table A1. In addition, Table A1 also includes the recommended pitch value S that matches each screw diameter. Table A1
Screw diameter D
Recommended pitch S
Recommended screw conveyor speed max
JB/T 7679 -- 95
The minimum screw diameter of the required screw conveyor depends on the required production rate of the conveyed material and the size of the bulk material. For bulk materials: the screw diameter D should be at least 10 times the maximum side length α of the particle. If the content of large particles is small, a smaller screw diameter is also allowed. But at least D≥4αmx
A6 Screw conveyor movement resistance
Due to the rotation of the conveying screw and the forward movement of the material, a number of resistances against movement are generated, which are composed of the following resistances: material running resistance FH;
No-load running resistance FN
Tilt resistance F
The above three resistances are all the resistances that the screw conveyor drive device must overcome in order to overcome friction, tilt and the movement of materials at the loading point.
Tilt resistance does not exist in all devices, it is a function of the line tilt. Among all resistances, only the tilt resistance can be accurately calculated.
A7 Screw conveyor driving power
Screw conveyor driving power:
P = PH + Pn + Pst
Where: PH
The power required when the material is running:
Pn—driving power of the screw conveyor when it is running without load; Pst
Tilt power.
A7.1 Power PH required for material operation
For a screw conveyor with a length of L, the power PH is the product of the conveying volume Im, the length L and the running resistance coefficient λ: 3600/g = lnLd
(A4)
The coefficient is specific to each conveyed material. Usually, the λ value is between 2 and 4. For several bulk materials that are often conveyed by screw conveyors, the λ values can be selected by referring to Table A2.
Table A2 Bulk density β and running resistance coefficient λ for several bulk materials Material category
Good fluidity, slightly abrasive
powdered and fine-grained materials
Aluminum sulfate
Material name
Baking soda (sodium bicarbonate)
Bauxite powder (dry)
Lan Ma beans (whole grains)
Borax (fine grains)
Coffee ( Roasted beans)
Cottonseed (dry, dust-free)
Fuller's earth (burned)
Material categories
Good-flowing, slightly abrasive
powders and granules
Medium- and poor-flowing
slightly abrasive
powders and granules
, and slightly abrasive
granular and lumpy materials
JB/T 7679—95
Continued Table A2
Material Name
Crushed Limestone
Sorghum (Grain)
Sorghum Flour
Phosphate Fertilizer
Rice (Bran Removed)
Sunflower Seed
Urea (Small Particles)
Wheat, Rye
Wheat (Sprout)
Anthracite (Piece Size Less Than 12mm）
Graphite flakes
Aluminum hydroxide
Ammonium nitrate
Ammonium sulfate
Barley flour (sprout)
Bran, bran
Calcium phosphate
Soda
Caustic soda flakes
Anthracite (washed crushed coal)
Coffee (instant)
0.45(0.5)
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