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Key words:
accuracy,
assembly, interchange, adjustment, components, production
process, workload, operation.
Assembly is the final stage of the production process. The finished product is
assembled from individual parts and components. The quality of assembly work
significantly affects the reliability and durability of machines during operation.
Assembled product - if the individual parts of the machine are not attached to each
other with sufficient accuracy, even if these parts are made with the required accuracy,
they will not work properly and reliably during use. That's why the assembly process
is so important in engineering. It should be added that in agricultural machinery, 20-
30% of the total workload is collected, while in other machines, the collection is 40-
60% of the total workload.
The quality of the assembly of the unit and the machine depends on the amount of
joints assigned to their parts, the technological methods that ensure the accuracy of the
sealing joint in their assembly. When assembling units and machines, the accuracy of
the sealing joint can be achieved by the method of full interchange, non-
interchangeable, group interchange, adjustment.
1. The methods of achieving the accuracy given in the assembly operations
significantly determine the accuracy of the product as a whole. In mass and serial
production, the method of assembly is widely used, providing full interchangeability.
Here, a quality combination creates any detail that goes into the assembly unit. Details
are not customized. The constructor sets the joints in the parts to be joined. If these
deposits are equal to or greater than the technological deposits, a complete exchange is
possible. The greater the number of parts in a unit's chain of measurements, the more
rigid each detail must be. Such conditions lead to a significant increase in production
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costs. If the constructor intended to break in the chain of parts, then any connection
obtained by the method of complete interchangeability must be formed. Then this
requirement can be easily verified using a few rules of the theory of basic equations
and chains of measurements. Examples of connections that are compatible with the
fully interchangeable method are:
≪
HT-250 lathe front SDH machine gearbox gears
and shafts
≫
,
≪
bulb and cartridge
≫
,
≪
plug and socket
≫
and such compounds like
those can be shown.
2. Assembling can also be done by non-exchange method. In this case, the dimensions
of the parts to be joined are assumed to be larger than before. It provides the required
accuracy of the locking link. However, not all objects are the same. The number of
objects of a given quality is determined using the apparatus of probability theory.
Additional costs are incurred to achieve the required size of the sealing link of objects
of poor quality. Under certain conditions, it can be almost small.
3. The given size or transfer can be provided by the group interchange method. In this
case, the design is smaller than the technologist. That is, as a result of the preparation
of details. The parts obtained after machining are always sorted into groups, and then
the appropriate transfer is provided by the selection of the covering and covering parts
in the appropriate groups (e.g., with bearing parts, cylinder block pistons and pushers,
etc.). The timing of selecting each pair of details can vary significantly. Therefore, the
group exchange method cannot be applied to the flow production method as shown.
4. Adjustment assembly is characterized by the fact that it belongs to the chain of
measurements, has the dimensions of details, technological parameters that is
characterized by the accuracy provided in this production. However, a closed link is
guaranteed to be transferred to the account of the size or compensating link.
5. To obtain the dimensions required for assembly by the method of reduction
(adjustment), the use of a special detail included in the assembly chain by sawing,
sanding, polishing and similar processing of the adjustable part, to determine the
accuracy of the sealing link 'allows riding. The required anterior clearance is provided
by double-stitching on the side surface of the bushing. This method of achieving a
given accuracy is used in the production of individual and small series.
The choice of assembly method depends on the type of production and is analyzed
using a chain of measurements. The full interchangeability method is commonly used
for short and simple chains. In other cases, it is convenient to use the method of free
exchange. Each adopted method needs to be analyzed for economic sampling.
Here are three ways to increase the accuracy of your locking link:
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1. Reducing the distribution area of the closing link by increasing the accuracy of each
link.
2. Reducing the number of links that make up a chain of measurements.
3. Reducing the transmission ratio of each component.
Using all of the listed methods provides the highest cost-effectiveness.
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