class. fixtures. Brief description of various systems of devices.

Classification of devices is carried out according to several criteria.

According to the intended purpose, the devices are divided into 5 groups:

1) Machine tools for installing and fixing workpieces on machines . Depending on the type of machining, these devices are divided into devices for drilling, milling, boring, turning, grinding and other machines. Machine fixtures make up 80-90% of the total stock of fixtures. They also include special-purpose devices (for bending, straightening and other operations).

2) Machine fixtures for installing and fixing a working tool that communicate between the tool and the machine, while the first type connects the workpiece with the machine. These include chucks for drills, reamers, taps, multi-spindle drilling and milling heads, tool holders for turret lathes and automatic machines, and other devices. These devices, also called auxiliary tools , are characterized by a large number of normalized designs.

With the help of devices of the first and second groups, the AIDS technological system is adjusted.

3) Assembly fixtures for connecting mating parts into units and products. They are used for:

a) fixing the base parts (assemblies) of the assembled product;

b) ensuring the correct installation of the connected elements of the part, product;

c) pre-assembly of elastic elements (springs, split rings, etc.);

d) for making tight connections.

4) Inspection devices are used for intermediate and final inspections, inspection of parts during mechanical assembly and inspection of assembled machine components.

This group also includes test and control-measuring stands.

5) Devices for gripping, moving and turning over processed workpieces and assemblies (the so-called transport and tilting devices) used in the processing and assembly of heavy parts and products.

Machine fixtures are called additional devices for metal-cutting machines, which make it possible to most economically, under given production conditions, meet the requirements inherent in the design of the part for the accuracy of the dimensions, shape and location of the machined surfaces of the parts.

Machine fixtures include: devices for installing and fixing workpieces on machines (devices), devices for installing and fixing cutting tools on machines (auxiliary tools).

In modern industries, the role of such devices is so great that in many cases the fixtures “merge” with the machine so that it is difficult to find the boundary between the machine and the fixture.

On a technological basis, machine tools are divided into devices for machines: turning, drilling, boring, milling, broaching, gear cutting, grinding, etc.

According to the degree of specialization, fixtures are divided into three groups, each of which includes the corresponding systems of machine fixtures provided for by ESTPP and GOST 14.305-73 “Rules for the selection of technological equipment”. In a separate system, it is possible to allocate means for mechanizing the clamping of machine tools (SMZSP).

Device system – a set of devices, the designs of which are assembled on the basis of uniform characteristic rules to ensure the unity of their implementation and use in certain organizational conditions of the technological process of manufacturing various parts.

UBP system – provides for the use of universal adjustable devices that do not require replaceable mounting and clamping elements. It includes complexes of universal fixtures included in tooling kits supplied to machine-building enterprises as accessories for machine tools. Recommended for single and multi-batch production.

UNP system – provides for the division of fixture elements into two main types: basic and replaceable. Base elements are a permanent, reusable part of a fixture, prefabricated according to relevant standards. Replaceable mounting and clamping elements of the setup can be universal (vises with interchangeable setups, dividing devices, rotary tables, etc.).

Recommended for small-scale and serial production, especially effective for group processing of workpieces.

The UUS system is used to mechanize devices in order to facilitate labor and increase its productivity. These include:

– easily moving floating tables;

– stands with tool catchers;

– separately arranged pneumatic, pneumohydraulic, hydraulic, magnetic, electromagnetic, electromechanical and other devices.

The UUS system includes means for mechanizing the clamping of machine tools (SMZSP).

Specialized non-adjustment devices (SBP) – are used to install workpieces that are similar in design and technological features and require the same processing and installation on one-dimensional or combined installation elements (for the same type of operations, it is possible to adjust the position of the installation elements). These include: devices for group processing of workpieces such as shafts, axles, bushings, glasses, flanges, disks, rings, brackets, housings, etc.

The SNP system , like the UNP system, includes basic elements and sets of adjustment elements, but is distinguished by a higher degree of mechanization of drives and the use of multi-place devices.

Recommended for specialized serial and large-scale production. An important feature of SNP (compared to UNP) is that each of them corresponds to the only possible basing scheme.

The USP system provides for a set of standard elements prefabricated from high-quality alloyed and hardened tool steels (12KhN3A, 48A, U10A, etc.) – parts and assembly units of high precision, from which various designs of special devices are assembled. After use, the device is disassembled into its constituent elements. USP elements have been in circulation for 18..20 years. It is recommended for single, small-scale, serial and various pilot productions, during the development of new types of products.

Typically, a USP kit contains 25-30 thousand parts, from which up to 300 fixtures can be assembled at the same time.

The main requirements for them: high reliability, wear resistance and durability.

PSA system – contains complexes of standard assembly units with base surfaces for assembling various devices. At the end of operation (when changing the production facility), the layouts are disassembled into assembly units and used in new devices.

It is recommended for serial and large-scale production in conditions of frequent change of manufactured products with a large number of modifications.

The NSP system contains complexes of predominantly standard assembly units, parts and blanks, as well as non-standard elements for the manufacture of high-performance special devices and replaceable special adjustments.

Recommended for stable high volume and mass production. These are single-purpose devices that are used to perform a specific operation when processing a specific workpiece.

According to the degree of mechanization and automation, devices are divided into:

manual;

mechanized;

ยท semi-automatic;

automatic.

In automated production, the device is an element of a complex transporting, loading and unloading complex.

The level of automation of a particular device is determined by the number of working methods covered by mechanization or automation.

In mechanized devices, with the help of a power drive, methods of fastening and detachment are performed, and when installing large parts, an additional basing method is also performed. The rest of the steps are done manually.

In semi-automatic devices, some of the techniques are performed automatically, without the participation of the worker, while the rest remain mechanized or manual.

In automatic devices, all methods, from loading and basing to the removal of machined parts, are carried out without the participation of a worker.

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