Application of spring energy accumulators in forging and pressing equipment

The development of forging and stamping production requires automation of various pressure treatment equipment. An important feature of the pressure treatment mechanisms is their inherent unsteady mode of operation, consisting of often alternating acceleration and deceleration, so the proportion of inertial loads is quite large. Such mechanisms are considered to be among the least efficient in terms of energy consumption parameters The low efficiency of the known designs is caused by the inability to exclude the influence of inertial forces on energy consumption and the speed of the equipment. The use of damping devices is not able to solve this problem, since they are designed to absorb a certain amount of energy and when the number of strokes per minute changes, they can cause an increase in dynamic loads.


Introduction
The low efficiency of the known designs is caused by the inability to exclude the influence of inertial forces on energy consumption and the speed of the equipment.The use of damping devices is not able to solve this problem, since they are designed to absorb a certain amount of energy and when the number of strokes per minute changes, they can cause an increase in dynamic loads.
The most promising way to eliminate inertial forces and automate forging and stamping operations is to design mechanisms with energy recovery, in which the kinetic energy of the moving links at the braking stage accumulates in the accumulator and is used for acceleration when performing the following action.In such constructions, inertial forces do not have a significant impact on the choice of engine power, which only needs to compensate for the cost of overcoming the friction force.
Automation of technological forging and stamping processes requires the development of mechanisms with energy recovery, which will increase the productivity of equipment and reduce energy consumption.To solve these problems, it is necessary to create new kinematic schemes of structures, as well as the choice of an energy accumulator that can best meet the task.
Most often, the classification of energy storage devices is used, dividing them into electrochemical, which convert electrical energy into chemical energy of substances, and physical energy storage devices that convert into mechanical energy.
Electrochemical energy storage devices include capacitive storage devices, molecular energy storage devices, inductive storage devices, rechargeable batteries, superconducting inductive storage devices, etc. Physical energy storage devices mainly include kinetic energy storage devices (flywheels), gravitational energy storage devices and spring energy storage devices.
One of the most powerful types of energy sources is capacitive energy storage.They are characterized by high reliability, efficiency of transmission of stored energy, and allow for the possibility of changing pulse parameters within a wide range.It is possible to use low-power chargers to charge them.But due to the low specific energy intensity, it is difficult to create capacitive energy storage devices with a stored energy of more than 10 MJ.Recently, work has been carried out to increase the specific energy consumption of capacitive storage devices by using more advanced components in the manufacture of capacitors, and optimizing the technology of their assembly.
A molecular energy storage device is a high-capacity capacitor, the accumulation of charge in which is carried out in a double electric layer in the volume of superporous carbon.This system has sufficiently high power characteristics for effective use as a fast-charging pulsed current source with an operating charge voltage of up to 500 V and an almost unlimited number of operating cycles.

Materials and methods
Depending on the duration of the discharge, the specific average power is 0.1-10 kW/kg.This is significantly higher than the specific power of many batteries, but the use of this type of storage is limited by the fact that the minimum discharge duration is characterized by millisecond times, and the generated currents are units of kiloamps.Most often, such devices are used in on-board diesel truck start-up systems, diesel locomotive start-up system and mobile X-ray medical equipment.Inductive energy storage devices have significant parameters of the output electrical pulse (more than 1011 watts), and high specific and economic indicators.The main difficulties in their application arise due to the reliability of reusable switching equipment.Also, at high values of discharge currents, significant electrodynamic forces occur in the coil.

Lead-acid batteries
The most common batteries are lead acid.The technology of production of these devices is well developed and these batteries are considered relatively cheap.
The principle of operation of lead-acid batteries is based on electrochemical reactions of lead and lead dioxide in an aqueous solution of sulfuric acid.The main disadvantages are considered to be large weight and size, sensitivity to negative temperatures and a limited number of discharge cycles.These batteries are often used to start car engines and to operate lifting and transport equipment (electric cars, loaders).

Nickel-cadmium batteries
The principle of operation is based on the formation of cadmium hydroxide at the anode and nickel hydroxide at the cathode.They have a higher energy consumption than lead-acid batteries, and are also capable of operating at low temperatures.Therefore, they are used in transport devices, aviation, military equipment.Recently, the use of nickel-cadmium batteries has been severely limited for environmental reasons.

Sodium-sulfur batteries
The principle of operation is based on the fact that the electrodes (molten sulfur and sodium) react, while sodium ions migrate through the separator.The resource characteristics of sodium-sulfur reach 4000 cycles with a discharge depth of up to 80-90%.The main disadvantage is considered to be the high operating temperature (approximately 300 °) and the associated risk of sodium ignition in an accident.They are used to regulate power output schedules and maintain the frequency of alternating current in large networks.

Lithium-ion batteries
The principle of operation of this electrochemical system is based on the introduction of lithium ions into various compounds at different electrochemical potentials.When voltage is applied to the electrodes, Li ions are transferred from the lithium cathode to the carbon anode.This process is accompanied by an oxidative reaction.When the load is applied to the system, metal ions begin to move in the opposite direction.Their main advantages are high energy density, and a large number of work cycles.These batteries have been used for 30 years, and the method of their manufacture is well developed.In the first samples of lithium-ion batteries, metal needles gradually began to appear on the lithium anode during operation.They broke through the electrolyte layer, and a short circuit occurred.Then graphite was used as the anode, which made it possible to avoid the problem with a short circuit.Currently, lithium ferrophosphate (LiFePO4) has been used for the cathode material, which allows safe use of the battery, as well as makes it energy efficient.
Nevertheless, there are still problems with storage and operation of the battery at low temperatures, as well as with loss of properties when charging it after partial discharge.

Thermal energy storage
A thermal accumulator is a heat-insulated container necessary for storing thermal energy.Thermal accumulators can be heated from the sun or from the power grid during the hours of the preferential tariff and smooth out periodic temperature fluctuations.As a rule, they are a container for storing hot water, sheathed with thermal insulation material.Such devices are able to store thermal energy for several hours and days, maintain the necessary temperature in the premises, they do not require frequent addition of fuel.Their main disadvantages are considered to be long heating, as well as significant dimensions and weight, which creates difficulties during their transportation and assembly.
Recently, developments have been underway for a battery capable of efficiently storing solar energy and releasing it if necessary.Research is being conducted on materials that will accumulate heat in chemical form.At the Massachusetts Institute of Technology (USA), a certain form of fulvalene hydrocarbon has been developed, which is capable of storing heat for a long time and heating up to 200 °C under the influence of a catalyst.But currently, the chemical components required to develop such a battery are too expensive for industrial applications.

Mechanical drives
The main disadvantage of all electrochemical storage devices is their low service life.Therefore, an important task is to develop such a drive that meets the requirements for durability, reliability and overall dimensions.The advantage of mechanical storage devices is their environmental friendliness and durability, ease of maintenance, and the highest specific power of all types of energy accumulators.
Modern materials make it possible to create storage devices with high energy intensity and the ability to quickly release stored energy.
For example, the company VYCON introduced a mechanical drive based on a flywheel, combined with an electric machine that works both as an engine and as a generator.
This storage device can both store and store mechanical energy, and convert and give it away in the form of electrical energy for further use.The kinetic energy of rotation of the flywheel is stored in the device, which, when charged with an electromechanical storage device, is unwound from a source of mechanical energy.During discharge, the stored mechanical energy is converted into electrical energy by means of an electric motor operating in generator mode.That is, an electromechanical storage device consists of three structurally combined parts -a flywheel, an electric motor and a generator.
Spring accumulators are most often used in drives for step movements and balancing devices.These batteries have a high service life and efficiency.They also allow you to implement the required dynamic modes in various devices, although they have not received mass use in design developments.

Results and discussion
To reduce energy costs for moving loads, recuperative devices based on the use of springs can be used.For example, this regenerative drive performs periodic rotation of the output link I with the help of the motor 2 and the spring 3. Fixing the device in a stationary state is carried out with the help of a lock 4. To rotate the link I, the lock 4 releases the disk 5, after which the motor 2 removes the entire system of links from a stationary state.When the crank 6 is rotated by an angle greater than the selfbraking angle, the spring 3 promotes acceleration of the moving links.After turning the crank 180 degrees, the braking stage begins, which ends when the crank is rotated 360° and the spring is stretched to the maximum.At this moment, the latch 4 enters the groove of the disc 5.
Similar devices can be used for industrial and forging manipulators.The grip of an industrial manipulator moves in a horizontal plane with the help of a spiral spring I, and its vertical movement is carried out with the help of a compression spring 2. Compensation for friction losses and fastening in extreme positions is carried out with the help of electromagnets of variable polarity 3, 4, 5.The adjustability of the coordinates of the fastening of electromagnets allows you to obtain the necessary angular and linear movements of the links.
To calculate the spring, it is necessary to know its working stroke, the force of the spring during working and pre-deformation, as well as the outer diameter of the spring itself. Let: -spring force during working deformation D = 30mm -the outer diameter of the spring Then you can perform the calculation:  As a result of the calculation, we take the average diameter of the spring D0 = 27 mm, the corresponding gap between the guide rod and the spring = 2 mm

Conclusions
Recuperator devices, due to the exclusion of the influence of inertial forces on the parameters of the energy carrier, provide a higher level of productivity, are less material-intensive and the usual simple technology is used for their manufacture.The energy consumption of a spring drive with energy recovery is determined by the friction losses in the elements of the spring accumulator.In this regard, energy costs are reduced several times compared to conventional structures.The given calculation example can be used in practice, if necessary, to determine the characteristics of the spring accumulator and perform a strength calculation to guarantee reliable and reliable operation of the device
ratio of the height in the free state to the average diameter and the limit value of this -

Table 1 .
Calculating the spring.