Presses: hydraulic, eccentric, rack. Driven crank or eccentric and friction presses Device and principle of operation of the equipment
Considered one of the most widely used technological processes. It is the processing of material with the help of pressure. The essence of the process is to push the workpiece through the hole of the matrix. Pressing is used to change the shape of the workpiece, cutting and compacting materials, squeezing out liquid, forging and stamping, etc. For the processing of materials by pressure, a special mechanism is used, which is called a press. One of the most common types is eccentric press.
- this is a machine that uses an eccentric
- slider travel can be easily adjusted
- can be single and double
The device and principle of operation of the equipment
is a mechanical machine in which an eccentric is used to move the slider. In other types of pressing equipment, a crankshaft is used. Principle of operation machine is as follows: the workpiece is in the form of a closed type, which is forced through the hole of the matrix. The shape and size of the cross section of the part of the workpiece that is extruded are the same as on the die. To clamp the workpiece, buffer devices are used, which are attached to the lower zone of the pressing equipment. They can be made using rubber and springs, as well as pneumatic, hydraulic and pneumohydraulic.MÜLLER Eccentric Press
Features and types
chief honors An eccentric press from a crank, for example, is the ability to easily adjust the stroke of the slider by turning the bushing related to the upper head of the connecting rod, which is located on the eccentric of the shaft. As practice shows, in the process of technological pressing, the connecting rod experiences heavy loads, which can lead to equipment breakdown, therefore, a safety washer is used to protect the connecting rod mechanism. It is located under the end face of the cylindrical thickening or the thrust bearing of the ball head. If the press is overloaded, the safety washer can be quickly replaced. There are single-column and double-column. For the first, the connecting rod is located on the cantilever end of the working shaft, and for the second, in the middle of the crankshaft bearings.Who is producing?
Companies such as RASTER(Germany), HEILBRONN (Germany), SANGIACOMO (Italy), KOMATSU (Japan), etc. When choosing eccentric press attention should be paid to it specifications: working force, distance between the working table and the slider, between the slider and the intermediate plate, stroke, stroke adjustment, table clamping surface, reach to the middle of the slider, number of feeds, etc.Pressing is one of the most common types of pressure processing of materials. The pressing process consists in changing the shape of the workpiece being processed by applying a lot of force to it through the deformation tool. Pressing is also used for compacting materials, squeezing out liquid, chopping and cutting materials.
By design, presses are divided into two main types:
- Mechanical
- hydraulic
One of the most common types of presses is the hydraulic press. Hydraulic presses are widely used in all branches of mechanical engineering, in the automotive industry and energy. The work of hydraulic presses is based on Pascal's law, according to which the pressure in a liquid is equally transmitted in all directions and equally in the entire volume. Therefore, having made a system of two communicating hydraulic cylinders with pistons different diameter, it is possible, by applying force to a small diameter piston, to obtain a greater force on a large diameter piston, the value of which depends on the liquid filling the cylinders and the ratio of their diameters. As a working fluid in hydraulic presses, as a rule, water or oil is used. This is due to their low compressibility, that is, the tendency to preserve constant volume under high pressure.
The main components of the hydraulic press: bed (usually column type), movable cross member, main (working) and return cylinders. In the designs of powerful presses, a hydraulic cylinder is provided, which balances the movable crossbar. The principle of operation of a hydraulic press is that, under the pressure of a fluid that is an energy carrier (working fluid), the plunger is pushed out of the main cylinder, moves the movable crossbar with the striker installed on it, and after resting on the workpiece located on the table, plastically deforms it.
In a mechanical press, the deformation of the workpiece occurs due to the reciprocating movement of the slider, driven by electric motor. The main components of a mechanical press are: a steel or cast-iron bed, a connecting rod, a movable cross member (slider). The eccentric press is mechanical press, which uses an eccentric instead of a crankshaft to move the slider.
The full range of sheet-working machines is in the corresponding section
This is a very useful device that will come in handy for those who often encounter such moments as pressing out and pressing in various bushings and bearings.
The main materials used in the assembly.
Channel 80mm, length 350-400mm.
Profile 40X40mm, length 1m.
Rod 12mm, 300mm long.
Tools.
Welding machine.
Bulgarian, wheels.
Racks are made of a profile 40X40mm, the height of these blanks is 350mm, the width along the outer edges is 270mm, so that there is 110mm between them.
Now Ivan will weld these racks to the base of the bed, and then he will show the next stage of work.
I welded the guide posts to the channel, then drilled 12mm holes.
A rod is placed in these holes.
An eccentric will be put on the rod.
This is how a hand press will work.
On the stud, it cuts threads on both sides.
On one side of the bar, the author tightly welds the nut.
I welded a 12mm nut on the outside of the rack, this is a seat for the second side of the bar.
Between the eccentric and the uprights put on two bushings, from jet thrust with a jig.
Here is the cut piece.
Bushings are needed so that the eccentric is located approximately in the middle.
Further, the author wants to strengthen this design, he will weld spacers. This sleeve will be welded to this crossbar, and to the uprights.
It is necessary to scald well, so that it turns out strong, monolithic construction.
Further, it will already install the moving rod feed mechanism itself.
Reinforcements installed and welded.
Now it will weld such a crescent to the movable rod.
At this point, the crescent will be welded.
And the rod will walk inside the sleeve.
The press mechanism will work according to following principle. In this position, there will be a crescent, it is clearly adjacent to the eccentric. When turning the eccentric, the crescent will move down, putting pressure on the stem. This results in a pressing effect.
Also, the fixed sleeve must be fixed on the frame itself. Welded the guide bushing to the profile.
It will be attached to the frame like this. Also, the crescent-stem design will have a small gap so that the eccentric has a working stroke.
This side also needs to be strengthened, because here weakness, it shouldn't exist.
After that, the author welded the guide bushing to the frame.
And you can already experiment a little with this press.
Ivan will try to press the 307th bearing into such a housing.
Installs the housing, inserts the bearing, substitutes the plate, for uniform distribution pressing force.
Puts the crescent moon in the correct position.
And lowers the eccentric lever.
The press did its job. Pressed such a large bearing flush.
Without any damage, clearly, quickly, and efficiently.
Now try the next, smaller one.
Everything, the roller is pressed.
This method of pressing allows you to gently and without damage to the bearing to press it into the housing.
If you use a hammer or any hard object to drive the bearing into the housing, it can be damaged. Usually the bearing race itself is damaged, there are such difficulties.
Therefore, it is much better to do it on the press. Here is such a good device - an eccentric press.
Of course, it has flaws.
It is necessary to make a guide so that the rod with the crescent does not rotate.
And also a little more to strengthen the rod attachment point here.
Also install the return spring on the stem itself, between it and the sleeve. This is necessary in order for the stem to automatically rise.
Also, this press can be used for other tasks. For example, for punching holes, bending at an angle, and many other processes.
This stud is made of ordinary steel 3, from ordinary rolled metal. Of course, under such loads, it will not be enough for a long time. Naturally, you need to make it from stronger steel.
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Driven crank or eccentric and friction presses.
In these presses, the rotational movement created by the electric motor is converted into the translational movement of the working parts with the help of crank shafts, therefore such presses are called crank presses. However, according to the method of connecting the crank shaft to the connecting rod, eccentric and crank presses are distinguished.
Rice. 23. circuit diagram eccentric (a) and crank (b) presses: 1 - slider, 2 - axle, 3 - connecting rod, 4 - eccentric disk, 5 - clip, 6 - shaft, 7 - clutch, 8 - flywheel, 9 - electric motor, 10 - side slider, 11 - bearings, 12 - crankshaft, 13 - gear, 14 - V-belt drive
In eccentric presses (Fig. 23, a), an eccentric disc 4 is mounted on the crank located at the end of the main shaft 6. The eccentric is enclosed in a cage 5 connected to the connecting rod 3 (or made in one piece with the connecting rod). When the shaft rotates, the eccentric moves the connecting rod up and down, as a result of which the slider 1 also moves. At the lower end of the connecting rod there is a ball heel (axis) 2, the swivel created by which ensures the movement of the connecting rod, repeating the movement of the crank or eccentric.
To adjust the initial (closed) height of the slider, the connecting rod is equipped with a screw, with which the length of the connecting rod is changed, and hence the distance between the slider and the press table. The main shaft receives rotation from the electric motor 9 through a belt drive and a pulley-flywheel 8, into which the clutch 7 is built (usually cam or friction). A control handle or a pedal is connected to this clutch through levers, with the help of which the working stroke of the press is carried out. Eccentric presses are used for trimming flash, sheet and die forging of small parts, and other similar operations.
In crank presses (Fig. 23, b), the connecting rod 3 is connected to the middle of the crank or crankshaft 12 through the bearing 11. These presses are made for high nominal forces and are used for bending operations, trimming flash and piercing holes.
The press is driven by an electric motor 9 through a V-belt 14 and a gear 13 gear. The side slider 10 is driven by an eccentric mounted on the end of the crankshaft. Thus, the press consists, as it were, of two presses: a crank and an eccentric. If with the help of the main slider on the press the flash is trimmed, then the side slider is used for flashing, or vice versa.
