Belt conveyor drive with worm gear - CP

Contents

1. Tape Conveyor Brief

2. Kinematic calculation

2.1. Electric motor selection

2.2. Determination of drive ratio

2.3. Defining torques

3. Computer Results Analysis

4. Worm Gear Calculation

5. Worm Gear Design

5.1. Case

5.2. Worm

5.3. Worm wheel

5.3.1. Dimensions and characteristics of h.

5.4. Control of engagement

5.5. Worm gear lubrication

5.5.1. Lubricant Selection

5.5.2. Lubricating devices

5.6. Lubrication of bearings

5.6.1. Lubricant Selection

5.6.2. Lubricating devices

6. Rolling bearings

6.1. Rolling bearings on worm

7. Bearing calculation

7.1. Calculation of high-speed shaft bearings

7.2. Calculation of low-speed shaft bearings

7.3. Calculation of drive shaft bearings

7.4. Select Bearing Fits

8. Calculation of shafts for strength

8.1. Calculation of high-speed shaft

8.2. Low Speed Shaft Calculation

8.3. Calculation of drive shaft

9. Calculation of connections

9.1. Low-speed shaft connection - worm wheel

9.2. Motor shaft connection - coupling

9.3. Slow shaft connection - coupling

9.4. Drive shaft connection - coupling

9.5. Drive Shaft - Drum Connection

10. Coupling calculation

11. List of used literature

I. Summary of the belt conveyor.

Belt conveyor - a continuous transport machine for horizontal movement of various loads, installed in a heated room. It can also move loose and loose materials. The conveyor is widely used for mechanizing loading and unloading operations, for transporting products in process flow lines, etc.

A large number of different conveying devices are currently known, differing in both operation and construction.

3. Analysis of calculation results on the computer.

When designing, the optimal parameters of the product should be selected that best meet various, often contradictory requirements: lowest weight, dimensions, cost: highest efficiency; required rigidity, reliability.

The use of computers for transmission calculations expands the amount of information used, allows you to make calculations with the selection of values ​ ​ (variation) of the most significant parameters: the method of thermal treatment or the materials used (permissible stresses), etc. The user needs to analyze the impact of these parameters on quality indicators and, taking into account the restrictions imposed, choose the best option.

The calculation is carried out in two stages. At the first, possible design solutions are found and the main quality indicators necessary for choosing a rational option are determined: mass of the mechanism, axial distance, wheel rim material, efficiency factor. When analyzing the results of the calculation, a rational option is chosen.

In the second step, all design parameters required for drawing release and the engagement forces required for shaft calculation and bearing selection are obtained for the selected option.

The weight of the product is most often taken as an optimality criterion.

Since in this case the production of gearboxes is serial, it is desirable that the size and cost are minimal.

5. Design of worm gear box.

5.1. Hull.

- material

The body is cast from gray cast iron. The choice is explained by its good casting properties, good workability on metal cutting machines, relatively low cost, and sufficiently high wear resistance. The strength and rigidity of cast iron is lower than steel, but in this case they are quite sufficient.

- casting method

This body has a fairly simple shape, without recesses and closed internal cavities. Therefore, by comparing casting according to meltable models and casting into shell molds, which is much cheaper than the first, preference is given to the second method. This method is mainly used for simple cast iron and steel moulds.

- wall thickness

The minimum thickness of the walls of the housing should be at least 6 mm, for our case we choose a thickness of 7 mm.

- distances between gear parts in the housing

So that the surfaces of the rotating wheels do not catch the inner surfaces of the walls of the housing, a gap is left between them, which is calculated by the formula:

a = L + 3 mm = 7 + 3 = 10 mm

Distance b between housing bottom and worm surface is taken as b > 3a = 30 mm

5.2. Worm.

This worm is cylindrical with a straight thread profile. It is made of steel 20X GOST 454371. In designing the worm, it is desirable to provide a free exit of the winding tool as well as ease of grinding the turns due to the free exit of the grinding wheel. During assembly, the worm is inserted into the gearbox through the bearing holes. Since the diameter of the opening in the shoulders is smaller than the outer diameter of the worm, radial thrust bearings are installed in a sleeve whose outer diameter is larger than the outer diameter of the worm.

From the calculation of the worm gear, we get that the worm is two-start. Length of cut part of worm b1 is determined by condition of use of simultaneous engagement of maximum number of wheel teeth.

displacement factor x = - 1;

number of worm entries z1 = 2;

All the diameters of the worm, as well as the length of the cut part, are already known.

D.E. = 18.3 mm

accept d = 19 mm. A face nut is installed on this diameter to press the bearings.

d p > d + 2t = 19 + 2 * 3 = 25 mm

d bp > dp + 3r = 30 mm.

5.3. Worm wheel.

5.3.1. Dimensions and characteristics of parts.

Low-speed shaft is calculated by formulas:

d > (5... 6) = 40 mm. - minimum possible shaft diameter

we accept the diameter of the output end of the drive shaft engaged with the worm wheel d = 46 mm.

The diameter for bearings is assumed based on the design of the hub of the worm wheel - dp = 50 mm.

The worm wheel is composite - the center of the wheel is made of steel (steel 3), a toothed rim is made of bronze (BR01OF1). The connection of the rim to the center should ensure the transmission of a large torque and a relatively small axial force.

The design of the worm wheel and the method of connecting the rim to the center depend on the volume of the exhaust. Since the production is serial, the toothed crowns are connected to the center by an interference fit. At constant rotation direction of worm wheel on external surface of center there provided is bead to which axial force is directed. Sharp edges on the ends of the crown are blunted with chamfers f ~ 0.5m, where m is the engagement modulus, rounded to a standard value.

Bead height t = 2.2 mm,

Bearing chamfer coordinate r = 2 mm

Chamfer size f = 1 mm.

The remaining dimensions are determined from the following ratios:

dst = (1.5... 1.55) d = 1.5 * 50 = 75

l =(0,8 …1,5) d = 1,2*50=60

S= 2m+0,05*b2=2*4+0,05*42=10

So = (1,2... 1,3) S =1.25*13=12,625

C =( 1,2 …1,3) S =1,2*12,625=15,8

h =0,15 b2 =0,15*53=6,3

t =0,8 h =0,8*6,3=5

5.4 . Adjustment of engagement.

A thin layer of paint is applied to the working surface of the worm turns, then the worm shaft is turned, slowing down the worm wheel shaft.

Contact spot indicates interaction of worm turns and worm wheel teeth. In a properly assembled gear, the contact spot is located symmetrically with respect to the middle cavity of the wheel rim.

If the contact spot is offset to the right or left, the worm wheel shaft must be moved axially to the right or left. It is carried out by transferring a part of the gaskets in one side to the other. The total thickness of the gaskets does not change.

5.5. Lubrication of worm gear.

5.5.1. Select lubricant.

A crankcase system is widely used to lubricate the gears. In our case, this method is not suitable because the circumferential speed of the worm wheel is too small (V = 0.56 m/s), so we raise the oil level ≈20 mm above the axis of the worm wheel. The wheel during rotation captures the oil, delivering it to the engagement zone .

The choice of lubricant is based on the experience of the machines.

Oils are preferred. The principle for assigning oil grade is as follows: the higher the circumferential speed of the wheel, the lower the viscosity of the oil and the higher the contact pressure in the engagement, the greater the viscosity of the oil. Therefore, the required viscosity of the oil is determined in

dependence on contact voltage and wheel circumferential speed as per Table 11.1 (1, p. 200). According to Table 11.2 (1, p. 200), the oil grade for lubrication of gear and worm gears is selected.

From Tables 11.1 and 11.2 (1, p. 200), the kinematic viscosity (20 mm2/s) is determined, and the oil grade is selected from it. For lubrication use I-T-S-320 oil as per TU 38 10141378 (Table 24.50, (1, p. 488)).

The depth of immersion in the worm wheel oil ≈ 145 mm.

5.5.2. Lubricating devices.

Since during the operation of the transmissions, the oil gradually loses its properties, ages, worsens, then it must be periodically changed. For this purpose, a drain hole is provided in the housing, which is closed by a plug with cylindrical thread M16 x 1.5. Since the cylindrical thread does not provide a reliable seal, an aluminum sealing gasket is placed under the plug.

To monitor the level of oil in the housing, an oil drain plug (similar to a drain plug) is installed.

During long-term operation due to heating of oil and air, the pressure inside the housing increases, which leads to oil leakage through seals and joints. To avoid this, the inner cavity of the housing is communicated with the external environment by installing a hatch with a perfume on top of the housing.

5.6 Lubrication of bearings.

5.6.1. Select lubricant.

In our case, access to the worm supports is difficult, so we use plastic lubricant

(TSIATIM201 as per GOST 626774) .We close the bearings with oil throwing rings. Lubricant occupies 1/32/3 of the free volume of the socket for bearings.

Lubrication of worm wheel supports is performed by direct access of I-T-S-320 oil to them.

5.6.2. Lubricating devices.

To supply PSM worm to bearings, we use oilers. Lubricant is supplied under pressure with a special syringe.

6. Rolling bearings.

6.1. - on the worm.

Since a significant axial force acts on the worm, one fixing support and one floating support are used. In the fixing support, we select conical roller bearings. Since radially thrust single-row bearings perceive the axial force of only one direction, it is necessary to install two such bearings in order to fix the shaft in both directions in the fixing support. The floating support is used taking into account the fact that the motor shaft enters one end of the shaft.

Preselect bearings: