Mechanical press slide output pressure control system and method

Abstract

A control system and method for the output pressure of a slider of a mechanical press, wherein a hydraulic control system for adjusting the output pressure of a slider is connected to the overload protection cylinder of the mechanical press, and the hydraulic control system includes a hydraulic accumulator connected in sequence, which is used to store the pressure oil of the overload protection cylinder; an oil source supply device with a setting valve group, which is used to replenish the system with oil and detect the system pressure; a proportional relief valve is used to set the output pressure of the slider; and the proportional relief valve is connected to the oil tank. The present invention also discloses a method for controlling the output pressure of a slider of a mechanical press, wherein a set of simple slider output pressure control devices is added to the overload protection device of a multi-link mechanical press, and while retaining the original overload protection function, the slider output pressure control device can also arbitrarily adjust the use pressure within a safe range. Such modification does not require a large cost investment, and is not only suitable for new presses, but also can be used to modify old mechanical presses at a relatively low cost, so that they have the function of adjustable slider output pressure, thereby expanding the scope of use of the mechanical press.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical presses, and in particular relates to a control system and method for a slide output pressure of a mechanical press. Background Art

[0002] Mechanical presses are widely used as main processing devices in the fields of automobiles, home appliances and aviation. The output force of the slider of the existing multi-link mechanical press changes with the change of the connecting rod movement angle. When the slider is near the lower limit, the angle between the connecting rods decreases, so when the slider moves to the lower limit, the slider is driven by the connecting rod to generate infinite output force.

[0003] For the safe operation of the equipment, multi-link mechanical presses are equipped with overload protection devices. When the output pressure is greater than the safety pressure set by the system, the safety valve of the overload protection opens quickly to drain the oil and unload. Moreover, for ordinary multi-link mechanical presses, production is mainly carried out in a fixed-stroke manner, and they are not sensitive to working pressure, as long as they do not exceed the safe use pressure. This leads to the use of large-tonnage presses to press small molds. If the output pressure cannot be accurately controlled, the small molds are likely to be crushed, causing safety hazards and unnecessary economic losses. If the mechanical press is to have the function of active pressure regulation, the main motor needs to be replaced with a servo motor. For large presses, the procurement cost of servo motors is high, which leads to a high threshold for mechanical servo presses, which are not suitable for procurement by small and medium-sized enterprises.

[0004] The structural principle of the traditional mechanical press is as follows Figure 3 As shown, it consists of an asynchronous induction motor 1, a clutch 2, a brake 3, a flywheel 4, a multi-link drive mechanism 5, a connecting rod 6, a slider 7, an overload protection cylinder 8 and a frame. The flywheel 4 is driven by the asynchronous induction motor to rotate in one direction and store rotational inertia energy. When the press is working, the brake 3 is opened upon receiving a command, the clutch 2 is closed upon receiving a command, and the flywheel 4 drives the multi-link drive mechanism 5 and the connecting rod 6 to move through multi-stage gears, driving the slider 7 to move up and down. When the press is in an emergency state of overload, the overload protection cylinder 8 unloads to ensure the safety of the press.

[0005] To this end, the present invention proposes a mechanical press slider output pressure control system and method, which is simple, easy, safe and reliable, suitable for use in ordinary mechanical presses, and more suitable for the modification of old mechanical presses. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a mechanical press slide output pressure control system and method. The device has a simple structure, is safe and reliable, and can quickly transform and upgrade the existing mechanical press to meet the needs of using a large-tonnage press to press a small mold.

[0007] The present invention is implemented as follows: a mechanical press slider output pressure control system, characterized in that: a hydraulic control system for adjusting the slider output pressure is connected to the overload protection cylinder of the mechanical press, and the hydraulic control system includes a hydraulic accumulator connected in sequence, which is used to store part of the pressure oil of the overload protection cylinder; an oil source supply device with a setting valve group, which is used to replenish oil to the system and detect the system pressure; a proportional relief valve is used to set the slider output pressure; and the proportional relief valve is connected to the oil tank.

[0008] The present invention also discloses a method for controlling the output pressure of a slider of a mechanical press based on the slider output pressure control device; when the slider is in a normal fixed stroke working mode, the overload protection cylinder plays the original overload unloading protection function;

[0009] When it is necessary to set the constant pressure mode of the output of the slider, the pressure value of the proportional relief valve is set according to the forming force requirements of the formed workpiece through the pressure-set proportional relief valve and the oil source to adjust the pressure of the cylinder. When the force of the connecting rod near the lower limit is greater than the set pressure, the oil is pressed into the accumulator to keep the slider working within the set pressure. When the slider rises after the pressing work is completed, the compressed oil returns to the overload protection cylinder through the accumulator to complete a working cycle.

[0010] The advantages and technical effects of the present invention are as follows: the present invention adds a set of simple slider output pressure control device on the basis of the overload protection device of the multi-link mechanical press. On the basis of retaining the original overload protection function, this slider output pressure control device can also arbitrarily adjust the use pressure within a safe range. This type of transformation does not require a large cost investment. It is not only suitable for new presses, but also can be used to transform old mechanical presses at a relatively low cost, so that it has the function of adjustable slider output pressure, thereby expanding the scope of use of mechanical presses. Large mechanical presses can be allowed to undertake the production tasks of small molds, thereby improving the utilization rate of customer equipment. In addition, the simple system is relatively convenient to maintain, which truly achieves the purpose of reducing customer investment costs, shortening manufacturer delivery time, and obtaining equipment with a simple structure, easy operation, safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural diagram of the slider part of the present invention;

[0012] Figure 2 is the pressure-stroke curve of the mechanical press of the present invention;

[0013] Figure 3 It is the mechanical principle of the traditional mechanical press;

[0014] Figure 4This is the pressure-stroke curve of a conventional mechanical press.

[0015] 1. Asynchronous induction motor; 2. Clutch; 3. Brake; 4. Flywheel; 5. Multi-link drive mechanism; 6. Connecting rod; 7. Slider; 8. Overload protection cylinder; 9. Oil supply equipment; 10. Accumulator; 11. Proportional relief valve; DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] See also Figure 1 A mechanical press slide output pressure control system, in which a hydraulic control system for adjusting the slide output pressure is connected to the overload protection cylinder 8 of the mechanical press, and the hydraulic control system includes a hydraulic accumulator 10 connected in sequence, which is used to store part of the pressure oil in the overload protection cylinder 8; an oil source supply device 9 with a setting valve group and pressure detection, which is used to replenish oil to the system and detect the system pressure; a proportional relief valve 11 is used to set the slide output pressure; the proportional relief valve 11 is connected to the oil tank.

[0018] The present invention also discloses a method for controlling the output pressure of a slider of a mechanical press based on the slider output pressure control device. When the slider output pressure control system of the mechanical press is adopted, the mechanical press can have two working modes, namely, the existing fixed-stroke working mode and the newly added constant pressure mode after optimization. In actual use, the normal fixed-stroke working mode and the constant pressure mode are switched according to actual working needs.

[0019] When the slider is in fixed stroke working mode, the mechanism still plays the original overload unloading protection function;

[0020] When it is necessary to set the constant pressure mode of the output of the slider, the pressure value of the proportional relief valve 11 is set according to the forming force requirement of the formed workpiece through the pressure-set proportional relief valve 11 and the oil source 9, so as to adjust the pressure of the oil cylinder 8. When the force of the connecting rod near the lower limit is greater than the set pressure, the oil is pressed into the accumulator 10 to keep the slider working within the set pressure. When the slider rises after the pressing work is completed, the compressed oil returns to the overload protection cylinder 8 through the accumulator 10 to complete a working cycle.

[0021] Application examples:

[0022] For example, the rear guard plate of a new model of washing machine requires a forming pressure of 300 tons, but the rated pressure of the smallest mechanical press in the customer's factory is 1000 tons. If the mold is put into use directly on-line, since the traditional mechanical press cannot accurately adjust the pressure, it is easy for the mold of the rear guard plate of the washing machine to be used at overpressure, or even the mold will be crushed. This requires adding an excessive pad or increasing the pressure resistance safety range of the mold, and this part of the cost is an invalid investment for the customer. If the 1000-ton press is equipped with the hydraulic system of this invention, the pressure of the proportional pressure regulating valve can be set to 300 tons. In this way, the customer only needs a very small cost to make the mechanical press accurately output 30% of the pressure, that is, 300 tons). Therefore, this invention integrates the overload protection and the setting control of the output pressure of the mechanical press for the first time.

[0023] from Figure 4 It can be seen that the maximum working stroke of the mechanical press is 13mm, that is, starting from 13mm above the lower limit of the slider, the slider can reach the nominal force, and as the slider moves downward, the slider output becomes larger and larger. Once the connecting rod angle is vertical, infinite force will occur.

[0024] Using the patent of this invention, Figure 2 It can be seen that a set of valve-controlled slider output pressure control device with adjustable pressure is arranged outside the overload protection cylinder. When the liquid pressure in the overload protection cylinder reaches the set value, the excess is stored in the accumulator. In this way, the press not only retains the original overload protection function, but also can realize the setting of any pressure value less than the nominal pressure, so that the press not only has the high efficiency of a mechanical press, but also has the high-precision pressure control of a hydraulic press.

[0025] This type of transformation does not require a large investment in costs. It is not only suitable for new presses, but also can be used to transform old mechanical presses at a relatively low cost, so that they have the function of adjustable slider output pressure, thereby expanding the scope of use of mechanical presses. Large mechanical presses can be used to produce small molds, thereby improving the utilization rate of customer equipment. In addition, the simple system is relatively easy to maintain, which truly achieves the purpose of reducing customer investment costs, shortening manufacturer delivery time, and obtaining simple, easy-to-use, safe and reliable equipment.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling the output pressure of a slide of a mechanical press, characterized in that: A hydraulic control system for adjusting the output pressure of a slider is connected to the overload protection oil cylinder of a mechanical press, and the hydraulic control system includes a hydraulic accumulator (10) connected in sequence for storing part of the pressure oil of the overload protection oil cylinder (8); an oil source supply device (9) with a setting valve group for replenishing oil to the system and detecting the system pressure; a proportional relief valve (11) for setting the output pressure of the slider; the proportional relief valve (11) is connected to the oil tank; the control method of the hydraulic control system is as follows: when the slider is in the normal fixed stroke working mode, the overload protection oil cylinder plays the original overload role. The invention has a load and unload protection function; when it is necessary to set the constant pressure mode of the output of the slider, the pressure value of the proportional relief valve (11) is set according to the forming force requirement of the formed workpiece through the pressure setting proportional relief valve (11) and the oil source supply device (9), so as to adjust the pressure of the oil cylinder (8). When the force of the connecting rod near the lower limit is greater than the set pressure, the oil is pressed into the accumulator (10) to keep the slider working within the set pressure. When the slider rises after the pressing work is completed, the compressed oil returns to the overload protection cylinder (8) through the accumulator (10) to complete a working cycle.

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