JPH0237456Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a device for positioning a bender head of a bender device for bending pipes and bars.

(Prior Art) Accurate pipe bending is required these days, and this is accomplished by determining the distance l between bender heads using a device as shown in Figure 1a.

In the figure, a is the pipe to be bent,
b, b are hydraulic cylinders c, c and rods d, d, respectively.
The bender heads b, b are connected via the roll type g, g, which have concave grooves, respectively.
As shown in Figure 1b, the pipe a
The guide member h swings around the roll mold g, g, and the roll mold g,
The bending process is performed by pressing dies i, which reciprocate toward the center of g. The starting state of the process is as shown in Figure 1c. When the straight pipe a along the grooves of the roll molds g and g is pressed by the press molds i and i, and then the guide member h is swung in the direction of the arrow. The pipe a is bent along a roll shape g. At intermediate portions of the rods d, d are provided locking devices f, f having cylinder sleeves e, e which are elastically deformed in the radial direction by supplying and discharging pressure oil. When setting the distance l between the bender heads b and b, the pressure oil to the locking devices f and f are controlled to loosen the cylinder sleeves e and e, and the hydraulic cylinders c and c are operated to set the distance l. Afterwards, locking devices f, f are applied to the rods d, d to fix them. Once the distance l is set, a load W is applied to the pipe a to bend it.

(Problem to be solved by the invention) When a load W is applied to bend the pipe a, the sleeves e, e of the locking devices f, f and the rods d,
Since the rods d bite into each other, resulting in a so-called galling condition, the rods d and d do not move smoothly even if the locking devices f and f are loosened, and the distance l is also deviated during the bending process, so it should be machined. There is an inconvenience that the parts and positions may be distorted, resulting in defective products, and the locking devices f, f are special products and expensive.

An object of the present invention is to provide an inexpensive positioning device that can accurately maintain the distance between bender heads, reduces the number of defective products, and does not cause so-called galling.

(Means for Solving the Problems) In the present invention, a pair of bender heads are each connected to a hydraulic cylinder, and the distance between both bender heads is maintained constant. It is composed of double rod type hydraulic cylinders, and the front chambers on the rod side connected to the bender head of each hydraulic cylinder are connected to each other by a first connection circuit, and the rear chambers on the opposite side of the front chambers are connected to each other by a first connection circuit. The first and second connection circuits are connected via an open center switching valve to a pump circuit and a tank circuit equipped with a back pressure valve, and each connection circuit is connected to the pressure of the other connection circuit. The above object is achieved by interposing a pilot check valve which is opened by the operator and allows fluid to flow into each chamber of the hydraulic cylinder.

(Function) When the switching valve is operated to connect the pump circuit to the second connection circuit and the tank circuit to the first connection circuit, the pilot check valve opens and the rod of each hydraulic cylinder adjusts the distance between both bender heads. Move forward to narrow it. The fluid in the front chamber of the cylinder flowing out into the first connection circuit is increased to the set pressure of the back pressure valve provided in the tank circuit while the cylinder is moving forward, and when the switching valve is returned to the neutral position, each pilot check valve is activated. The valve is closed and the pressure in the front and rear chambers of the hydraulic cylinder is maintained at the set pressure of the back pressure valve.

When the load W associated with bending is applied to the bender heads, the load is also applied to the hydraulic cylinder, and the preset distance between the bender heads changes, so the distance between the bender heads is set by taking this change into account.

Now, let the load acting on the hydraulic cylinder due to bending work be W', and the operating resistance pressure of the cylinder be L,
Assume that the pressure in the pump circuit is P and the set pressure of the back pressure valve is P'. The distance between the bender heads is set by moving the rods of each cylinder backward and then forward. During constant operation, the pressure in the front chambers of both cylinders is P', and the pressure in the rear chambers is P'. P is larger than +L.

When the switching valve is returned to the neutral position and the operation of the cylinder is stopped, the pressures in the front and rear chambers are averaged to P'+L/2. The load applied to the cylinder when the bending process starts is W', and if the value Q obtained by dividing this force by the pressure receiving area π/4 (D ² - d ² ) is smaller than or equal to P', then the force relationship is is the force when two identical springs as shown in Figure 3 are connected in series, both ends are fixed, and W'÷π/4(D ² - d ² )=Q is applied to the middle part. is equal to the balance of Here, D is the inner diameter of the cylinder, and d is the outer diameter of the rod. Therefore, when the bending process begins, the anterior chamber
Pressure increases by Q from P'+L/2, and the rear chamber is P'+L/
Balance is achieved by lowering the pressure by Q from 2. The fluid in the front chamber is compressed by the increased pressure, and the rod moves in the load direction by that amount. The amount of movement Δl is calculated by (S×
Q)/2K, and its value is less than or equal to (S×P')/2K.

Therefore, by adding this Δl to the distance between the bender heads before starting the bending process, the load W' applied during the process can be adjusted by changing the volume of the cylinder.

Since two cylinders are actually used, the distance between the bender heads is precisely adjusted using a rotary encoder or the like so that the distance between the bender heads is l+2×Δl.

This device does not require the use of expensive equipment such as a locking device with a cylinder sleeve, so it can be manufactured at low cost, and its operation is simple and has good power efficiency because it uses the hydraulic pressure of the cylinder for driving the bender head. Become.

(Example) An example of the present invention will be explained with reference to FIG.
1 is a pipe to be bent, 2, 2 is a pair of bender heads, 3, 3 is a double rod type hydraulic cylinder, and the rods 4, 4 are substantially similar to those shown in FIGS. 1a to 1c. A bender head 2, 2 having the following configuration is attached.

5, 5 are the front chambers of the hydraulic cylinders 3, 3; 6;
6 is a rear chamber on the opposite side of the front chamber 5 and the piston 14, 7 is a first connection circuit that connects the front chambers 5, 5, and 8 is a second connection that connects the rear chambers 6, 6 to each other. In the circuit, the first and second connection circuits 7 and 8 are connected to a pump circuit 10 connected to a pump and a tank circuit 11 connected to a tank via an open center type electromagnetic switching valve 9 having a neutral position.

Reference numeral 12 indicates a back pressure valve constituted by a direct relief valve provided in the tank circuit 11, and reference numeral 13 indicates a pilot check valve provided in each connection circuit 7, 8, which guides the pilot pressure from the connection circuit on the other side and supplies it to each chamber. 5 and 6 allow fluid to flow in.

When the switching valve 9 is switched to the position 9a, the fluid in the pump circuit 10 flows into the rear chambers 6, 6 of each cylinder 3 via the second connection circuit 8, and the fluid in the front chambers 5, 5 flows into the opened pilot chamber. It flows from the first connection circuit 7 to the tank circuit 11 via the check valve 13.
Since the tank circuit 11 is provided with a back pressure valve 12, the pressure in the front chambers 5, 5 becomes the set pressure P' of the back pressure valve 12, and the pressure in the rear chambers 6, 6 increases the operating pressure of the cylinder 3. The pressure becomes P'+L, which is the sum of L. The distance between the bender heads 2 and 2 is l+Δl×
2, the switching valve 9 is returned to the neutral position. As a result, the pressure in each front chamber 5 and rear chamber 6 is averaged.
It becomes P′+L/2.

Next, when the bending process of the pipe 1 is started, a load of W' is applied to the bender heads 2, 2, but with this load, the rods 4, 4 of each cylinder 3 are displaced by Δl, and the gap between the bender heads 2, 2 is expected to be length l
This allows for accurate bending.

(Effects of the invention) As described above, in the present invention, a pair of bender heads are connected to double rod type hydraulic cylinders, and the front and rear chambers of each cylinder are connected to the first and second connections provided with pilot check valves, respectively. Since each circuit is connected to the pump circuit and the tank circuit equipped with a back pressure valve through an open center type switching valve, the bender head can be connected within the cylinder in consideration of the displacement of the rod that occurs during bending. It is possible to confine pressure within the area, allowing accurate bending.
It can be manufactured at a low cost because it can be constructed from common inexpensive equipment on the market, and it is easy to operate because positioning can be done only by setting the bender head, without the complexity of operating a conventional locking device. is consumed, so there are effects such as less power loss and better efficiency.

[Brief explanation of the drawing]

Figure 1a is an explanatory diagram of a conventional example, and Figure 1b is an illustration of a conventional example.
Detailed view of the bender head in Figures 1c and 1b.
FIG. 2 is an explanatory diagram of the machining start state, FIG. 2 is an explanatory diagram of the embodiment of the present invention, and FIG. 3 is an explanatory diagram of the force relationship. 2, 2... Bender head, 3, 3... Hydraulic cylinder, 4, 4... Rod, 5, 5... Front chamber,
6, 6... Rear chamber, 7... First connection circuit, 8...
2nd connection circuit, 9... switching valve, 10... pump circuit, 11... tank circuit, 12... back pressure valve.

Claims (1)

[Scope of utility model registration request] In a system in which a pair of bender heads are each connected to a hydraulic cylinder and the distance between both bender heads is maintained constant, each hydraulic cylinder is composed of a double rod type hydraulic cylinder, and each hydraulic cylinder The front chambers on the rod side connected to the bender head of the rod are connected to each other by a first connection circuit, and the rear chambers on the opposite side of the front chamber are connected to each other by a second connection circuit, and both the first and second connections are made. The circuit is connected to a pump circuit and a tank circuit equipped with a back pressure valve via an open center type switching valve, and each connection circuit is opened by the pressure of the other connection circuit to allow fluid to flow into each chamber of the hydraulic cylinder. A bender head positioning device for a pipe bender, etc., which includes a pilot check valve that allows inflow.