Estimated reading time: 11 minute
On the basis of studying the development status of bending machinery at home and abroad and the existing problems of my country’s bending machinery, according to the requirements of parts operation, a bending machine that uses hydraulic components to drive one-way operation is designed. This model adopts a crank slider mechanism, which solves the bending of thin plates in actual production. And through the motion analysis and calculation of the mechanism, through the transformation of the mechanism, a bending machine that keeps the bending force always perpendicular to the part during the processing process is realized. The bending machine is characterized by simple structure, easy operation, and high work efficiency. And introduced in detail the use characteristics of the self-made bending machine tools.
Design Method of Making Bending Machine
- Task analysis
Design and manufacture-a vertical sheet metal bending machine, the press head of the machine is hydraulically driven up and down, and its working cycle: rapid descending, slow pressing (bending), and rapid retreat. The given conditions are:
Bending force 1×106V
Slider weight 1.5 × 104N
Rapid no-load descent stroke 180mm
Speed (V1) 23mm/s
Slow down pressure (bending) stroke 20mm
Speed (V2) 12mm/s
Fast return stroke 200mm
Speed (V3) 53mm/s
The hydraulic cylinder adopts a V-shaped sealing ring, and its mechanical efficiency is 0.91.
- Self-made bending machine determination of the plan
Judging from the working conditions of the bending machine, the external load and working speed are constantly changing over time. Therefore, the design of the hydraulic circuit must meet the requirements of constant changes with the load and the speed of the actuator. Therefore, two methods can be selected: variable pressure throttle speed control circuit and positive displacement speed control circuit.
Comparing the advantages and disadvantages of the above two schemes, the open volume speed control circuit of the pump cylinder is compared with the variable pressure throttling circuit, the speed rigidity and load capacity are better, the speed range is also wider, the work efficiency is higher, and the heat is generated. It is the smallest. Considering that the maximum bending force is 2.2xl06N, the pump cylinder open volume speed control circuit is selected.
- Drafting of system hydraulic diagram
Considering that the hydraulic press requires a large amount of power when working, the volumetric speed regulation method is adopted;
- In order to meet the extreme changes in speed, the pressure compensation variable hydraulic pump is used to supply oil, that is, the hydraulic pump supplies oil at full flow when it drops rapidly. When converted to slow pressurization, the flow rate of the pump decreases, and the final flow rate is O;
- When the hydraulic cylinder returns in the reverse direction, the flow of the pump is restored to the full flow of oil. The movement direction of the hydraulic cylinder is controlled by a three-position four-way Y-type electromagnetic reversing valve and a two-position two-way electromagnetic reversing valve. When stopping, the three-position four-way reversing valve is in the neutral position to unload the hydraulic pump;
- In order to prevent the pressure head from being out of control due to its own weight during the descending process, a one-way valve is installed on the road where the hydraulic cylinder has a rod;
- In order to maintain the pressure when suppressing, a hydraulic control check valve is installed on the rodless evacuating oil path and the refilling solid oil path;
- In order to make the pressure head of the hydraulic cylinder fall more and more due to its own weight, when the three-position four-way reversing valve is in the right position, a relief valve should be set at the oil return port as a back pressure valve to return oil. The road is under pressure so as not to lose control of the speed;
- In order to make the pressure constant when the system is working, an overflow valve is set at the outlet of the pump to adjust the system pressure. Because the machine adopts proximity switch control, the proximity switch is used to switch the on and off of the reversing valve to implement automatic control;
- In order to prevent the pressure of the hydraulic cylinder from being too high during compression, a pressure relay is set up, and the pressure relay is used to control the maximum pressure. When the pressure reaches the set pressure elbow, the pressure relay sends out an electrical signal to control the solenoid valve to maintain pressure;
In summary, the hydraulic system principle of the self-made bending machine is as follows:
- The length,width and height of the fuel tank are determined
Because the ratio of the width, height, and length of the fuel tank is 1: 1-2: 2-3, the ratio selected here is 1:1.5:2. From this, the width, length, and height of the fuel tank can be calculated as approximately 1600mm, 1100mm, and 770mm respectively. And choose the separate fuel tank design in the open fuel tank. Its advantage is convenient maintenance and debugging, reducing the influence of hydraulic oil temperature rise and hydraulic pump vibration on mechanical performance; its disadvantage is that it occupies a large area.
Introduction of Self-Made Bending Machine Tools
Homemade tools are divided into three categories. The first includes work and measurement tools to help you perform operations (for example, side stops). The second type can help you measure or qualify parts to ensure that operations and parts meet specifications. These may include radius or countersunk angle gauges. The third is the operating tools to assist the operation of the machine, such as dial indicator mounts and custom tools.
Needle gauge. These Self-Made Bending Machine tools measure flanges from features to bend lines, and ancient handicrafts are still valuable today. When the recalled size is the size from the feature to the bend line, and you measure the size from the feature to locate the bend, the size will be retained, and any error will be between the feature and the edge. The distance from the edge to the polyline, all errors will be displayed in the called dimension.
Side regulation. The side gauge is the right or left stop along the Z-axis of the bed or brake. The parts are held by the back gauge to maintain the size 795, while the lateral measurement rules block the previous flanges, embossing, hardware, and other features from under the punch.
Bending wire gauge. This helps align the drawn bend line with the center of the punch radius. It can be made of a square turning tool mounted on its edge and cut back at one end. When placed on the V-shaped mold, the cut-in part of the gauge will form a vertical line, and the operator can use the vertical line to align the drawn bending line with the bending center.
Assuming you can use lasers, you can make various measuring tools very easily. In fact, all the examples can be easily implemented internally except for one of the following examples.
Radius gauge. Once you have completed the initial procedure for cutting the radius gauge on the laser, you only need to zoom in or out of the laser program to create a gauge for the radius that needs to be measured. In many ways, this is better than buying a set of imperial or metric gauges. Nowadays, most of us are air-bending, and when we air-form a workpiece, its inner diameter is a percentage of the mold opening. The floating radius rarely becomes one of the fixed values in the purchased gauge set. By making your own radius gauges, you can precisely match them to the radius that needs to be generated in the part.
Rule. Using a laser, you can cut the ruler to the exact size and create the exact mark you need, whether it’s imperial or metric. It is as accurate as of the general store rules. It may not be exactly as accurate as inspection-level tools, but it can keep you at a sufficient distance in many situations in the workshop.
Steel ball. You can chamfer the hole with steel ball bearings of various sizes to slightly change its diameter. Regardless of whether the hole is too large or the size is too small, these steel balls are tools needed to preserve prototype parts.
S hole angle gauge. Likewise, they are easy to cut on the laser and easy to use. Like a custom radius gauge, you can cut it to the exact angle of the counterbore that needs to be measured.
Dial indicator holder. Suppose you want to check the accuracy and repeatability of the back gauge, or you need to manually adjust the back gauge on a non-CNC machine. The dial indicator is just the right tool, but installing it on the base of the bending machine will require another custom tool, albeit very simple. Just by welding the pin to the bolt, the pin can be inserted into any of the many threaded holes on the base of most bending machines.\
Small punch and die. If a very thin material is to be formed and a very narrow mold opening (such as 0.035 inches) is required, it may be difficult to find one. 0.500 inches is displayed. A square strip with two narrow V-shaped grooves creates a miniature double V-shaped mold that can be snapped into a custom bracket. The bracket is made of rigid polyurethane and is designed to fit European-style mounting rails.
You may not find the highlight of the job in the tool catalog. Here, I used a very thin cutting rule to cut the cardboard box into a certain shape, thereby effectively punching a hole with a radius of 0. You can cut the rule to the required length, and even add the tears, cuts, and other features needed to form the part. You also need to make a punch holder similar to a European wedge or a custom punch for planers.
Centering such a small punch on such a small mold requires very fine adjustments, which are much more subtle than the average centering process. You can do this by again making a bracket that is mounted on the base of the press brake and holds the micrometer head. The micrometer is attached to a self-made tool that is clamped to the mold mounting rail. This allows you to enter and exit the rail in 0.0001 inches.
How to center a 0 radius punch into a 0.035 inch wide V die? Of course, you cannot put your head between the bed and the ram. But you can get a magnifying glass with the proper focal length for the centering process. You will need to cut a few blocks to install on the European track style (or whatever track style you have) to accommodate a small webcam. Now, with some monitors for viewing, you can center the tool.
Polyurethane mold. You can make a small urethane tool kit with a deflection rod and an air channel under the pad to reduce the forming tonnage.
Gusset tool. Suppose you need to form a gusset, which is a rib that is perpendicular to the bend. Just place it between the two parts of the tool and this little gem will help you produce a hemmed bend. Small shims on both sides allow material to flow out of the gusset tool. The gusset tool is made of stainless steel. Just cut it into a size slightly shorter than the height of the tool, and it’s ready to use.
Pay attention to the load that the gusset tool will bear during use. The tonnage will be concentrated on the edge of the gusset tool and may be embedded in the mounting rail or base of the machine. It is best to place a protective strip on both sides of the Self-Made Bending Machine mold and under the entire length to fully lift the tool to protect it.
Gauge block. If you are using a traditional planer tool, you need to use a gauge block to calibrate the back baffle to the bending center during installation.