accessory for suspension springs compression

Description of the process problem.

In the practice of domestic and foreign car service, operations to remove or install suspension springs are widespread. In this case, the springs must be previously loosened or compressed according to the condition of their mounting dimensions between other parts of the suspension. The compressed spring has a sufficient margin of kinetic energy so that, during careless removal from the suspension unit, it suddenly opens up and leaves the place of its installation with great force. Sudden expansion of the spring as an elastic element causes not only an increase in its axial size (opening to a completely uncompressed state), but also the ability to fly out of the serviced unit laterally at high speed. This situation in more than half of cases ends with severe injuries to the personnel serving the car, damage to a number of standing cars, car service equipment.

Description of existing factory-made structures and home-made trees.

In order to prevent such situations, methods of mounting and dismantling compression springs such as relaxing or compressing the spring with the help of mounting blades and supports for suspension units should be permanently excluded from the practice of servicing the suspension. The most effective methods of performing these operations are the use of professional spring removers.

In practice, the extractors used in the maintenance of the spring on the car look like spring coils grips tightened by a screw with metric, thrust or trapezoidal threads (Figure 6.1.). Their main possibilities are exhausted by a stroke of up to 300 mm. It is possible to use a different number of these ties per one spring - two, three, four. Recently, however, stationary suspension spring tightening devices have also been used (Figure 6.2.). These devices can have not only a screw drive, but also a hydraulic drive.

In combination with a single-grip compression device, the hydraulic drive has a noticeable power gain compared to the screw drive. In addition, the screw drive must be dimensionally adapted to a specific value of the axial length of the compression spring - that is, have a certain working length. The hydraulic actuator typically has sufficient rod travel for different lengths of springs .

These devices are made both in Russia and abroad, but reliable samples have a high price (from 20,000 rubles and above), and cheap (from 3 thousand rubles) - in turn - a short service life. This explains the fact that a considerable number of workshops perform on their basis the original designs of extractors that do not have patent justification and are not checked for compliance with work loads. Most of these extractors have as a power part - a screw with metric threads with a collapse angle of 60 degrees. At the same time, a trapezoidal thread with an angle of collapse of turns up to 30 degrees has a large reserve in terms of reliability, power characteristics and ease of travel.

Description of the proposed design and its advantages over analogues .

The design specification should accept the development of such a extractor design for compression springs, which would consist of a minimum number of parts, had a pressure screw with trapezoidal threads and at the same time had high mechanical strength of its component parts.

Kinematic diagram of the extractor is shown in Fig.6.3. At its base two beams 1 and 3 are hingedly connected by bolt 2. Each of the beams has at its working end pressing pancakes 5, which must compress the spring or expand it. The pair of "screw nut" 4 with trapezoidal thread is driven by crank 6, thus beams 1 and 3, and with them pancakes 5 can move in axial direction towards each other or in reverse direction. This allows you to eventually reduce or increase the height of the spring, compressing it to the contact of the turns, or expanding it to a free state. The screw of this device is supposed to be limited to 100 mm, which quite satisfies the dimensional row of compression springs of domestic and a number of foreign cars.

The initial data for the design should be considered:

Geometric parameters (Fig. 6.4.):

The axial length of the extractor a is from the hinge connection of the beams to the middle of the screw, mm - 480;

The axial length of the extractor b is from the middle of the screw to the working elbow of the upper and lower beams, mm - 140;

Axial length of working elbow of beams with, mm - 80;

Height of screw part between beams d, mm - 140;

High-altitude parts of the elbows of beams e, mm - 183;

The axial part of the extractor f - from the beginning of the handle to the hinge connection of the beams, mm - 140.

Elastic force of compression spring F0 = H - 7800 .

Having indicated the initial data, it should be noted that the main hazardous points of the structure are a hinge bolt (hazard factor - cut), the place of stop of the screw against the upper beam (hazard factor - bend) and working pancakes for the spring (hazard factor - bend ).

The described structure is practically immune to distortions of the compressible spring due to uniform distribution of load between supporting working pancakes. This makes it possible to use a wrench at moderate rotation speeds as a working tool in the process of working with springs. In the case of conventional "bracing" structures that compress the spring from different sides, the use of mechanized equipment becomes dangerous due to the possibility of unexpected spring skew between the grips of two opposite bracing devices.

Another advantage of the described screw tightening device is the ability to quickly position the working pancakes along the extreme compressible turns of the spring. The device can be turned on the side of the wheel arch, its small height dimensions do not make it difficult to supply the support surfaces for the extreme turns of the spring.

Description of the technology of using the spring extractor and safety precautions.

The operating technology of the spring extractor of this design involves both manual and mechanized use of it. In manual use, crank arm 6 (Figure 6.3.) rotates clockwise and compresses the spring, the reverse direction of rotation causes the spring to uncompress. With a mechanized method of use, the crank handle is removed from the square (dimensions according to the DIN standard for a manual tool with crack heads), the nut spindle is connected to the latter through the adapter coupling. The recommended rotation speed is up to 200 rpm. When working with the wrench, take precautions - the spring compression in time must not be prolonged, in order to avoid breakage of the extractor and possible uncompressing of the spring. The work should be carried out only when the car wheel is removed, previously it should be possible to free up the "service zone" in the wheeled niche to supply the extractor - remove the extra suspension elements. When working with the extractor, it is forbidden to find the worker in the close space of the wheeled niche of the car in order to avoid dangerous situations. It is forbidden to hang the extractor by the frame of the car, platforms and hoists of the hoist. It is also forbidden to disassemble the extractor structure without technical need, store the disassembled extractor for a long time only after preservation of movable parts with plastic lubricant Litol24.