Molding device

Abstract

To provide a forming apparatus which can quickly perform feedback control for keeping position and speed of a slide to the preset position and speed even when a load is abruptly applied to the slide.SOLUTION: A forming apparatus 1 includes a cylinder 11, a piston 12 which can be inserted to the cylinder 11, a slide 15 which is connected to the piston 12 and can press an object W to be formed, a bed 17 which is opposed to the slide 15 and can press the object W to be formed between the slide 15 and the bed, a liquid chamber 13 which is provided in the cylinder 11, supplies working fluid L to an inner part and, thereby, can apply a force to the direction of the bed 17 with respect to the slide 15, and a boosting mechanism 25 which can raise a pressure P of working fluid L in the liquid chamber 13. The boosting mechanism 25 raises the pressure P of the working fluid L in the liquid chamber 13 while causing the slide 15 before starting pressing to the object W to be formed by means of the slide 15 to approach the object W to be formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a molding apparatus. [Background technology]

[0002] Conventionally, molding devices that operate using the pressure of hydraulic fluid such as hydraulic oil move a slide connected to a piston inserted into a single-acting cylinder toward the bed while controlling the pressure of the hydraulic fluid supplied to a fluid chamber provided in the cylinder with a pump. Then, the object to be molded is pressed between an upper mold attached to a slide and a lower mold attached to a bed to mold the object to be molded (see, for example, Patent Document 1).

[0003] The molding device moves the slide toward the object to be molded or stops it without load during the time period when the slide approaches the object to be molded before molding or when the slide is stopped before molding starts. The pressure in the liquid chamber of the cylinder moves the slide toward the bed with very low pressure. When the molded object expands and deforms, the slide is kept stationary and the slide and bed (upper and lower molds) support the load from the expanding molded object. When the mold is closed, the pump is operated to press the molded object and close the mold. Once the mold is closed, the pressure on the piston is controlled to be removed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-81190 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, when the molding object is expanding and deforming, the slide is kept stationary, but a load may be suddenly applied from the molding object side that is trying to expand, and the load may be applied upward to the slide. In this case, feedback control is activated to keep the upper mold position constant, and the pump supplies hydraulic fluid to the liquid chamber of the cylinder, increasing the pressure in the liquid chamber until it reaches a pressure force commensurate with the load from the molded object side, thereby maintaining the slide in a stationary state and maintaining the upper mold position. However, in some cases, it takes a certain amount of time (several seconds) for the above feedback control to be completed, making it difficult to quickly perform the feedback control.

[0006] For example, the same applies to a molding device that performs forging, drilling, etc. on a workpiece. In other words, if the load increase rate of the workpiece is very high, when the die comes into contact with the workpiece and forging or the like begins, the slide may suddenly receive a load from the workpiece, and a load may be applied to the slide in the opposite direction to the slide's movement.

[0007] Therefore, feedback control is activated to increase the pressure in the liquid chamber of the cylinder, thereby controlling the position and speed of the slide to maintain the set position and speed. However, in some cases, it takes a certain amount of time for the feedback control to take effect, making it difficult to quickly perform the feedback control.

[0008] The present invention has been made in consideration of the above points, and aims to provide a molding device that can quickly perform feedback control to maintain the position and speed of the slide at the set position and speed even when a sudden load is applied to the slide from the object to be molded. [Means for solving the problem]

[0009] The molding device according to the present invention comprises: A cylinder; a piston insertable into the cylinder; a slide connected to the piston and capable of pressing the object to be molded; a bed facing the slide and capable of pressing the molding object between the bed and the slide; a fluid chamber provided in the cylinder, the fluid chamber being capable of applying a force to the slide in the direction of the bed by supplying hydraulic fluid therein; a pressure increasing mechanism capable of increasing the pressure of the hydraulic fluid in the fluid chamber; Equipped with Before the slide starts to press the molding object, while the slide is being moved closer to the molding object, the pressure increasing mechanism increases the pressure of the hydraulic fluid in the liquid chamber. 、 When the slide receives a load from the molding object, the position of the slide is kept constant. .

[0010] Further, the molding device according to the present invention is A molding apparatus including a slide to which an upper mold can be attached, and a bed facing the slide to which a lower mold can be attached, After molding, the upper mold or the lower mold Rabe Equipped with an extrusion mechanism that extrudes molded products, The extrusion mechanism includes: A cylinder; a piston insertable into the cylinder; a knockout pin connected to the piston and capable of pressing the molding object; a fluid chamber provided in the cylinder, into which a hydraulic fluid is supplied so that a force can be applied to the workpiece by the knockout pin; a pressure increasing mechanism capable of increasing the pressure of the hydraulic fluid in the fluid chamber; and the pressure-boosting mechanism increases the pressure of the hydraulic fluid in the liquid chamber while the knockout pin is approaching the molding object before the knockout pin starts to push out the molding object, When the knockout pin receives a load from the workpiece, the position or speed of the knockout pin is maintained at a set position or speed.

[0011] Further, the molding device according to the present invention is A molding apparatus including a slide to which an upper mold can be attached, and a bed facing the slide to which a lower mold can be attached, After molding, the upper mold or the lower mold Rabe Equipped with an extrusion mechanism that extrudes molded products, The extrusion mechanism includes: A cylinder; a piston insertable into the cylinder; a knockout pin connected to the piston and capable of pressing the molding object; a fluid chamber provided in the cylinder, capable of applying a force to the workpiece by supplying a hydraulic fluid therein; a pressure increasing mechanism capable of increasing the pressure of the hydraulic fluid in the fluid chamber; and the liquid chamber is provided on a surface of the piston inserted into the cylinder that faces away from the knockout pin, A second fluid chamber is provided in the cylinder on a side of the piston facing the knockout pin, While the knockout pin is applying a force to the workpiece, the pressure-boosting mechanism increases the pressure of the hydraulic fluid in the liquid chamber and also increases the pressure of the hydraulic fluid in the second liquid chamber, applying a pressure to the piston in the opposite direction to the pressure applied by the hydraulic fluid in the liquid chamber. [Effects of the Invention]

[0012] According to the present invention, a molding device can be provided that can quickly perform feedback control to maintain the position and speed of the slide at the set position and speed even when a load is suddenly applied to the slide from the object to be molded. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of the configuration of a molding device according to a first embodiment. [Figure 2] 1 is a graph showing the relationship between the compression amount and pressure of a working fluid containing a gas dissolved therein. [Figure 3] 10 is a graph showing the relationship between the compression amount and pressure of the working fluid when the proportion of gas dissolved in the working fluid is 10% under atmospheric pressure. [Figure 4]FIG. 10 is a diagram illustrating an example of the configuration of a molding device according to second and third embodiments. [Figure 5] 10 is a diagram illustrating that a small amount of hydraulic fluid needs to be supplied when the pressure of hydraulic fluid in the first fluid chamber of the cylinder is increased from a previously high pressure state. FIG. [Figure 6] 10 is a diagram illustrating how the amount of expansion of the hydraulic fluid when the molding object is extruded is reduced by increasing the pressure of the hydraulic fluid in the first fluid chamber and the second fluid chamber of the cylinder of the extrusion mechanism. [Figure 7] FIG. 10 is a diagram illustrating a configuration example of a molding device of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a molding apparatus according to the present invention will be described with reference to the drawings. In the following description, the terms upper side, upper direction, lower side, lower direction, etc. are used in accordance with the up-down direction in the drawings, but the present invention is not limited to this case.

[0015] [First embodiment] FIG. 1 is a diagram illustrating an example of the configuration of a molding device according to a first embodiment of the present invention. In this embodiment, the molding device 1 includes a cylinder 11. A piston 12 is inserted into the cylinder 11, and a first liquid chamber 13 is provided above the piston 12 inside the cylinder 11 (on the side of the piston 12 that is farther from a slide 15, which will be described later).

[0016] A second fluid chamber 14 is provided below the piston 12 inside the cylinder 11 (the portion of the piston 12 around the piston rod on the side facing a slide 15 described later). In this embodiment, the cylinder 11 is a so-called double-acting cylinder in which the first fluid chamber 13 and the second fluid chamber 14 are provided above and below the piston 12, respectively, as described above.

[0017] A slide 15 is connected to the lower end of the piston 12, and an upper die 16 is attached to the lower surface of the slide 15. In addition, a bed 17 is disposed below the slide 15 so as to face the slide 15, and a lower mold 18 is attached to the upper surface of the bed 17.

[0018] Further, the slides 15 are respectively fitted with ram rods 20 of retraction cylinders 19 . Although Figure 1 shows a case where the slide 15 is pulled upward by the retraction cylinder 19, it is also possible to provide the retraction cylinder 19 below the slide 15 and configure the slide 15 to be pushed up by the retraction cylinder 19.

[0019] The molding device 1 also includes a supply and discharge system for hydraulic fluid L, such as hydraulic oil, to the first fluid chamber 13 of the cylinder 11. In this embodiment, the supply and discharge system for the hydraulic fluid L is configured so that the hydraulic fluid L, such as hydraulic oil, flows into the first fluid chamber 13 of the cylinder 11 from the tank 21 via a pre-fill valve 22 which is opened and closed by a pilot valve 23.

[0020] A pump 25 is attached to the first fluid chamber 13 of the cylinder 11 via a supply pipe 24. In this embodiment, the pump 25 is a pump whose pressurization can be controlled by a servo motor. In addition, the supply pipe 24 is provided with an on-off valve 26 between the first fluid chamber 13 of the cylinder 11 and the pump 25 .

[0021] When the on-off valve 26 is opened while the pump 25 is operating, the pressure of the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11 increases. In this manner, in this embodiment, the pump 25 functions as a pressure increasing mechanism that can increase the pressure of the working fluid L in the first fluid chamber 13.

[0022] By supplying hydraulic fluid L into the first fluid chamber 13 of the cylinder 11, the pressure of the hydraulic fluid L in the first fluid chamber 13 increases, and a force can be applied to the slide 15 downward, i.e., in the direction of the bed 17. In addition, by applying force from the first liquid chamber 13 to the slide 15 in this manner, the workpiece W can be pressed between the slide 15 and the bed 17 (between the upper mold 16 and the lower mold 18).

[0023] In addition, a discharge pipe 28 for discharging the working fluid L in the supply pipe 24 to the tank 21 is connected to the supply pipe 24, and the discharge pipe 28 is provided with an on-off valve 29 for depressurizing, etc. Furthermore, when the on-off valve 29 of the discharge pipe 28 is opened, the hydraulic fluid L is discharged from the first fluid chamber 13 of the cylinder 11 and the supply pipe 24, and the pressure of the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11 decreases.

[0024] In this embodiment, the pressure of the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11 is controlled by adjusting the rotation of the servo motor of the pump 25, adjusting the flow rate of the hydraulic fluid L with the on-off valve 26, and controlling the opening and closing of the on-off valve 29. In the drawing, reference numeral 27 denotes a pilot valve for adjusting the opening and closing of the on-off valve 26.

[0025] On the other hand, the molding device 1 is provided with a supply and discharge system for the hydraulic fluid L to the second fluid chamber 14 of the cylinder 11. Specifically, the hydraulic fluid L flows into the second fluid chamber 14 of the cylinder 11 from the tank 21 via a pre-fill valve 30.

[0026] Further, a discharge pipe 31 is attached to the second fluid chamber 14 of the cylinder 11, and a counterbalance valve 32 is provided in the discharge pipe 31. A pressure switching pipe 33 equipped with a pressure switching valve 34, a pressure reducing valve 35, etc. is connected to the counterbalance valve 32. The counterbalance valve 32 is configured to discharge the hydraulic fluid L from the discharge pipe 31 to the tank 21 when the pressure of the hydraulic fluid L in the discharge pipe 31 exceeds the hydraulic pressure in the pressure switching pipe 33.

[0027] The pressure reducing valve 35 reduces the fluid pressure in the pressure switching pipe 33 to, for example, 0.1 MPa (atmospheric pressure). In addition, in this embodiment, the pressure switching valve 34 switches the hydraulic pressure in the pressure switching pipe 33 to either a predetermined hydraulic pressure or 0.1 MPa (hydraulic pressure determined by the pressure reducing valve 35), but it is also possible to configure it so that the hydraulic pressure can be switched in stages or continuously between these hydraulic pressures, and to configure the counterbalance valve 32 so that the pressure of the working fluid L in the discharge pipe 31 or the second hydraulic chamber 14 of the cylinder 11 can be switched in stages or continuously.

[0028] Next, before describing how to control the pressure of the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11 in the molding apparatus 1 according to this embodiment, a molding apparatus 100 of a comparative example shown in FIG. 7 will be described.

[0029] 7, a molding apparatus 100 of the comparative example includes a cylinder 101, and a piston 102 is inserted into the cylinder 101. A liquid chamber 103 is provided above the piston 102 inside the cylinder 101. A slide 104 is connected to the lower end of the piston 102, and an upper mold 105 is attached to the lower surface of the slide 104. A bed 106 is disposed below the slide 104, and a lower mold 107 is attached to the upper surface of the bed 106.

[0030] A hydraulic fluid L such as hydraulic oil flows into the fluid chamber 103 of the cylinder 101 from a tank 110 via a pre-fill valve 111 that is opened and closed by a pilot valve 112 . A pump 114 is attached to the liquid chamber 103 of the cylinder 101 via a supply pipe 113. An opening / closing valve 115 is provided on the supply pipe 113 between the liquid chamber 103 of the cylinder 101 and the pump 114.

[0031] Further, a discharge pipe 117 for discharging the working fluid L in the supply pipe 113 to the tank 110 is connected to the supply pipe 113, and the discharge pipe 117 is provided with an on-off valve 118 for depressurizing, etc. In FIG. 7, the safety valve is indicated by the symbol s.

[0032] When the on-off valve 115 is opened while the pump 114 is operating, the pressure in the liquid chamber 103 of the cylinder 101 increases. When the on-off valve 118 of the discharge pipe 117 is opened, the working fluid L is discharged from the liquid chamber 103 of the cylinder 101 and the supply pipe 113, and the pressure in the liquid chamber 103 of the cylinder 101 decreases. In this way, the pressure in the liquid chamber 103 of the cylinder 101 is controlled by controlling the operation of the pump 114 and the opening and closing of the on-off valve 115 and the on-off valve 118, etc.

[0033] In addition, reference numeral 116 in the drawing denotes a pilot valve for opening and closing the on-off valve 115 . In addition, piston rods 109 of retraction cylinders 108 are attached to the slides 104. Although Fig. 7 shows a case where the slides 104 are pulled upward by the retraction cylinders 108, it is also possible to provide the retraction cylinders 108 below the slides 104 and configure the slides 104 to be pushed up by the retraction cylinders 108.

[0034] For example, when expansion molding of a workpiece W such as a metal pipe is performed using such a molding device 100, the piston 102 is lowered in the cylinder 101 to lower the slide 104. Then, when the workpiece W is sandwiched between the upper mold 105 and the lower mold 107, the movement of the slide 104 is temporarily stopped.

[0035] In this state, a high-pressure fluid is sealed in the metal pipe, which is the molding object W, to cause expansion and deformation, and then the slide 104 is moved to the mold clamping position to clamp the molding object W. Then, the piston rod 109 of the retraction cylinder 108 pulls up the slide 104 and returns it to its original position. At this time, the working fluid L in the fluid chamber 103 of the cylinder 101 is returned to the tank 110 via the pre-fill valve 111, etc., as the piston 102 rises. In this way, one process is completed.

[0036] In this case, the molding device 100 generally moves the slide 104 toward the workpiece W or stops it without load during times such as when the slide 104 approaches the workpiece W before molding or when the slide 104 is stopped before molding begins. That is, the slide 104 is moved toward the bed 106 at a very low pressure (minimum operating pressure) in the liquid chamber 103 of the cylinder 101.

[0037] When the molding object W expands and deforms, the slide 104 is kept stationary, and the slide 104 and the bed 106 (upper mold 105 and lower mold 107) bear the load from the expanding molding object W. When the molds are closed, the pump 114 is operated to increase the pressure in the liquid chamber 103 to a predetermined pressure, and the molding object W is pressed against the molds to close the molds. When mold clamping is completed, the on-off valve 118 is opened to drain the hydraulic fluid L, reducing the pressure in the supply pipe 113 and the fluid chamber 103 of the cylinder 101, thereby removing the pressure on the piston .

[0038] Next, we will explain why it becomes difficult to quickly perform feedback control to maintain the position and speed of the slide 104 at the set position and speed when a load is suddenly applied from the workpiece W to the slide 104 in the molding device 100 of the comparative example shown in Figure 7, for example, during expansion molding of the workpiece W.

[0039] When a load is suddenly applied upward from the workpiece W to the slide 104 during expansion molding, a high pressure begins to build up in the working fluid L in the fluid chamber 103 of the cylinder 101 . At this time, if gas is dissolved in the working liquid L, the bulk modulus of the working liquid L is smaller than when no gas is dissolved, and the amount of compression of the working liquid L (the volume of the working liquid L compressed) is therefore larger. As a result, the amount of working liquid L sent to the liquid chamber 103 and the supply pipe 113 by operating the pump 114 increases, and feedback control takes time.

[0040] The bulk modulus K is generally expressed as follows, where V is the volume of the working fluid L and P is the pressure applied to the working fluid L.

number

[0041] Since the volume of a gas changes polytropically, PV κ =C …(2) The following relationship holds true: where the polytropic exponent κ is approximately 1.4 and C is a constant.

[0042] Taking the derivative of equation (2), we get

number

[0043] On the other hand, if the volume V contains a gas at a ratio of x, the apparent bulk modulus of the working fluid L is:

number

[0044] Also, when the pressure of the working fluid L, which has gas dissolved in it at a rate of x0 under atmospheric pressure, is increased by Δp, the rate x of gas dissolved in the working fluid L under pressure p is:

number

[0045] If the atmospheric pressure is 0.1 MPa, then Δp = p - 0.1 MPa. If the bulk modulus K1 of the working fluid L without dissolved gas is 1650 MPa, then equation (6) can be obtained by substituting equation (4) and κ = 1.4:

number

[0046] Next, to calculate the compression amount of the working fluid L (the volume of the working fluid L compressed), dP in the definition equation for the bulk modulus (see equation (1)) is calculated as follows: dP=dP n =P n -P n-1 …(8) It is defined as:

[0047] The volume of the working fluid L under atmospheric pressure is V0, and the pressure P n The volume of the hydraulic fluid L at this time is V n Then,

number

[0048] Using equations (1), (8), and (9),

number

number

[0049] The pressure acting on the working fluid L in which the gas is dissolved is P nThe amount of compression of the working fluid L at this time is the volume reduction dV of the working fluid L for each increase in pressure P applied to the working fluid L. n (See equation (10)) Therefore, if the compression amount of the working fluid L is expressed as ΔV below, the compression amount ΔV of the working fluid L with gas dissolved therein can be calculated using equations (10) and (11) as follows:

number

[0050] If the relationship between the amount of compression ΔV [liter] of the working fluid L containing dissolved gas and the pressure P [MPa] calculated in this way is plotted on a graph, it will look like the graph shown in Figure 2, for example. In this case, the volume V0 of the working fluid L under the above atmospheric pressure, i.e., the volume V0 of the working fluid L in the fluid chamber 103 of the cylinder 101 and the supply pipe 113, was set to 220 [liter], and the calculation was performed by increasing the pressure of the working fluid L in increments of 2 [kPa]. Also, in the graph, A to G show the calculation results when the proportion x0 of gas dissolved in the working fluid L under atmospheric pressure is 0 [%,] 0.1 [%,] 0.3 [%,] 1 [%,] 5 [%,] 10 [%], and 20 [%], respectively.

[0051] For example, when the working fluid L is a working oil, it is generally said that 6 to 12% of gas is dissolved in the working fluid L under atmospheric pressure. Therefore, looking at Figure 3, which shows the graph for x0 = 10[%] in Figure 2, we can see that when the pressure of the working fluid L of 220 [liters] as described above increases from atmospheric pressure (0.1 [MPa]) to, for example, 4 [MPa], the volume of the working fluid L decreases by approximately 28 [liters].

[0052] For example, consider the case in which, in expansion molding, the piston 102 is pushed up together with the slide 104 by the load from the molding object W as described above. The area of ​​the top surface of the piston 102 in the single-acting cylinder 101 in FIG. 7 (cylinder bore area) S1 is 2500 cm 2], when the slide 104 receives a load of approximately 100 [t] from the workpiece W, the pressure of the hydraulic fluid L rises from atmospheric pressure to 4 [MPa]. This corresponds to the piston 102 of the single-acting cylinder 101 being lifted by approximately 110 [mm].

[0053] In this way, when the volume of the hydraulic fluid L decreases by approximately 28 liters, it is necessary to operate the pump 114 by feedback control to supply approximately 28 liters of hydraulic fluid L into the fluid chamber 103 of the cylinder 101 and the supply pipe 113. However, for example, if the discharge capacity of the pump 114 is 600 liters / minute, it takes approximately 2.8 seconds to supply approximately 28 liters of working fluid L into the liquid chamber 103 or the supply pipe 113, which indicates that the response of feedback control, etc. is slow.

[0054] In the above comparative example, for example, when the slide 104 receives a load of approximately 200 t from the workpiece W during expansion molding, the pressure of the working fluid L of 220 liters rises from atmospheric pressure to 8 MPa. Therefore, as can be seen from the graph in Figure 3, in this case, the volume of the working fluid L decreases by approximately 33 liters. For example, if the discharge capacity of the pump 114 is 600 liters / minute, it takes about 3.3 seconds to supply about 33 liters of hydraulic fluid L into the liquid chamber 103 and the supply pipe 113, which also results in a slow response to feedback control, etc.

[0055] Next, a method for controlling the pressure of the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11 in the molding device 1 according to this embodiment will be described. In the molding device 1 of this embodiment (see Figure 1), as described above, before the slide 15 starts to press against the workpiece W (including when the upper mold position is kept constant during expansion molding), the pump 25 (pressure-boosting mechanism) increases the pressure of the working fluid L in the first liquid chamber 13 of the cylinder 11 while the slide 15 is being brought closer to the workpiece W.

[0056] That is, as described above, in the molding apparatus 100 of the comparative example, during the time period when the slide 104 approaches the workpiece W before molding, the liquid chamber 103 of the cylinder 101 is in a state of no load (minimum operating pressure). In contrast to this, in the molding device 1 according to this embodiment, the pressure of the working fluid L in the first fluid chamber 13 of the cylinder 11 is increased in advance while the slide 15 is being brought closer to the workpiece W.

[0057] For example, in this embodiment, when performing the expansion molding as described above, while the pump 25 is operated to bring the slide 15 closer to the workpiece W, the pressure of the working fluid L in the first fluid chamber 13 of the cylinder 11 is increased to, for example, 4 [MPa]. When the pressure of the working fluid L is increased from atmospheric pressure to 4 MPa in this way, approximately 28 liters, which corresponds to the compressed volume of the working fluid L, is sealed in advance, as mentioned above (see Figure 3).

[0058] Therefore, while the slide 15 is approaching the workpiece W, the pump 25 is operated to supply the compressed volume of the hydraulic fluid L, approximately 28 liters, into the first fluid chamber 13 of the cylinder 11 and the supply pipe 24 in advance. Then, in this state, the slide 15 is lowered, and when the workpiece W is sandwiched between the upper mold 16 and the lower mold 18, the slide 15 is stopped.

[0059] With the slide 15 stopped in this manner, if the slide 15 receives a load of, for example, approximately 100 t from the workpiece W, as described above, the pressure of the working fluid L increases by another 4 MPa, so that the pressure of the working fluid L increases from 4 MPa to 8 MPa. In this embodiment, when the slide 15 approaches the workpiece W, approximately 28 liters of hydraulic fluid L has already been supplied to the first fluid chamber 13 of the cylinder 11 and the supply pipe 24. Therefore, as can be seen from Figure 3, when the pressure P of the hydraulic fluid L rises from 4 MPa to 8 MPa, it is sufficient to supply approximately 5 liters (=33-28) of hydraulic fluid L to the first fluid chamber 13 of the cylinder 11 and the supply pipe 24.

[0060] Therefore, for example, if the discharge capacity of the pump 114 is 600 [liters / minute], it takes only about 0.5 seconds to supply about 5 [liters] of working fluid L into the liquid chamber 103 and the supply pipe 113. In this way, with the molding device 1 of this embodiment, even if the slide 15 suddenly receives a load from the side of the workpiece W that is about to expand during expansion molding, for example, it is possible to quickly perform feedback control, etc. to keep the upper mold position constant.

[0061] In the case of expansion molding, after the workpiece W, a metal pipe, is expanded and deformed by sealing a high-pressure fluid inside it, the slide 15 is moved to the mold clamping position to clamp the workpiece W, and the sealed fluid is further pressurized to perform molding. Then, the ramrod 20 of the retraction cylinder 19 pulls up the slide 15 and returns it to its original position. At this time, as the piston 12 rises, the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11 is returned to the tank 21 via the pre-fill valve 22, etc. In this way, one process is completed.

[0062] On the other hand, the control characteristic of the present invention, which involves using the pump 25 (pressure-boosting mechanism) to increase the pressure of the working fluid L in the first fluid chamber 13 of the cylinder 11 while the slide 15 is being brought closer to the workpiece W, as described above, can be applied not only to the case of performing expansion molding of the workpiece W, but also to the case of performing forging, drilling, etc. on the workpiece W.

[0063] That is, for example, if the load increase rate of the workpiece W is very high, when the descending upper die 16 comes into contact with the workpiece W and starts forging, etc., the slide 15 may be suddenly subjected to a load from the workpiece W, and a large load increase may occur on the slide 15 in an upward direction (i.e., in the opposite direction to the direction toward the bed 17). Therefore, in this case, as in the above case, while the slide 15 is being brought closer to the workpiece W, the pump 25 (pressure-boosting mechanism) is used to supply hydraulic fluid L to the first fluid chamber 13 of the cylinder 11 and the supply pipe 24 in advance, thereby increasing the pressure of the hydraulic fluid L in the first fluid chamber 13.

[0064] With this configuration, even if the upper mold 16 comes into contact with the workpiece W and a large load is suddenly applied to the slide 15, the amount of working fluid L supplied from the pump 25 to the first fluid chamber 13 of the cylinder 11 and the supply pipe 24 can be smaller than when the pressure of the working fluid L in the first fluid chamber 13 is increased from atmospheric pressure. Therefore, it is possible to quickly perform feedback control, etc., to increase the pressure of the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11 and maintain the position and speed of the slide 15 as set.

[0065] As described above, according to the molding device 1 of this embodiment, the pump 25 (pressure-boosting mechanism) is configured to increase the pressure of the working fluid L in the first liquid chamber 13 of the cylinder 11 while the slide 15 is being brought closer to the workpiece W before the slide 15 starts to press against the workpiece W (including in the case of expansion molding). Therefore, even when a load is suddenly applied to the slide 15 from the workpiece W, feedback control, etc. can be performed quickly to maintain the position and speed of the slide 15 as set (including when the upper mold position is kept constant), compared to when the pressure of the working fluid L in the first fluid chamber 13 of the cylinder 11 is increased after the slide 15 comes into contact with the workpiece W and begins to press.

[0066] As can be seen from the above description, the control in the molding device 1 according to this embodiment relates to the pressure control of the hydraulic fluid L in the first fluid chamber 13 of the cylinder 11. Therefore, the cylinder 11 does not necessarily have to be a double-acting cylinder, and the present invention can be applied even if the cylinder 11 is a single-acting cylinder (for example, see the cylinder 101 in FIG. 7).

[0067] However, it is possible to use the pulling force of the retraction cylinder 19 as a resistance load to counteract the pre-increased pressure of the working fluid L in the first fluid chamber 13 of the cylinder 11 while the slide 15 is being brought closer to the workpiece W, but the retraction cylinder 19 would have to be larger to generate the necessary resistance load. For this reason, a double-acting cylinder is used as the cylinder 11 in the present embodiment.

[0068] That is, a cylinder 11 is used in which a first liquid chamber 13 is provided on the side of the piston 12 inserted into the cylinder 11 that is farther from the slide 15, and a second liquid chamber 14 is provided on the side of the piston 12 inside the cylinder 11 that faces the slide 15. Furthermore, when the pump 25 (pressure-boosting mechanism) increases the pressure of the working fluid L in the first fluid chamber 13 while the slide 15 is being brought closer to the workpiece W as described above, it is possible to increase the pressure of the working fluid L in the second fluid chamber 14, thereby generating a resistance load on the piston 12 in the opposite direction to the load generated by the working fluid L in the first fluid chamber 13.

[0069] In this case, for example, if the pressures of the first and second liquid chambers 13 and 14 are adjusted so that the loads applied to the piston 12 from the first and second liquid chambers 13 and 14 are the same, the loads applied to the piston 12 from the first and second liquid chambers 13 and 14 will be balanced, and the operation of the pump 25 will make it possible to move the slide 15 closer to or stop the workpiece W.

[0070] Specifically, for example, as described above, the area S1 (cylinder bore area) of the top surface of the piston 12 in the first fluid chamber 13 of the cylinder 11 is 2500 cm 2 ], and the area S2 of the lower surface of the piston 12 in the second fluid chamber 14 is 1 / 4 of that (S1 / S2=4). In this case, when the pressure of the working fluid L in the first fluid chamber 13 is increased to, for example, 4 [MPa] as described above, the pressure of the working fluid L in the second fluid chamber 14 is simultaneously increased to 16 [MPa] to counter the pressure of the working fluid L in the first fluid chamber 13.

[0071] In this case, for example, the pressure switching valve 34 (see FIG. 1) is configured to be able to switch the fluid pressure in the pressure switching pipe 33 between 0.1 [MPa] (atmospheric pressure) and 16 [MPa]. Then, by operating the pressure switching valve 34 to switch the hydraulic pressure in the pressure switching pipe 33 to 16 [MPa], the counterbalance valve 32 can switch the balance pressure of the hydraulic fluid L in the discharge pipe 31 and the second hydraulic chamber 14 of the cylinder 11 to 16 [MPa].

[0072] Furthermore, for example, after the slide 15 is subjected to a sudden large load from the workpiece W that is about to expand, the pressure switching valve 34 can be operated to switch the hydraulic pressure in the pressure switching pipe 33 to 0.1 MPa and release the counterbalance pressure (the pressure of the hydraulic fluid L in the second liquid chamber 14 can be set to atmospheric pressure), thereby making it possible to make the load generated by the cylinder 11 equivalent to that of a hydraulic system with no resistive load at the stage of mold closing after expansion molding.

[0073] As mentioned above, if the counterbalance valve 32 is configured to be able to switch the pressure of the working fluid L in the discharge pipe 31 or the second fluid chamber 14 of the cylinder 11 in a stepwise or continuous manner, it becomes possible to vary the resistance load applied to the piston 12, and it becomes possible to vary and adjust the load (differential load) applied to the piston 12 in a stepwise or continuous manner.

[0074] [Second embodiment] On the other hand, instead of applying the present invention to the cylinder 11 of the molding device 1, it is also possible to configure it to be applied to an extrusion mechanism that extrudes the molding object W from the upper mold 16 or the lower mold 18 after molding. In the following description, the terms upper side, upper direction, lower side, lower direction, etc. will be used in accordance with the up-down direction in the drawings, but the present invention is not limited to this case.

[0075] FIG. 4 is a diagram illustrating an example of the configuration of a molding device according to a second embodiment of the present invention. 4 shows a case where the present invention is also applied to the cylinder 11 side of the molding device 1, but the present invention does not have to be applied to the cylinder 11 side of the molding device 1. Also, in FIG. 4, a case where the extrusion mechanism 40 is provided on the lower mold 18 side will be described below in which the workpiece W is extruded from the lower mold 18, but the extrusion mechanism 40 may also be provided on the upper mold 16 side.

[0076] As shown in FIG. 4, the extrusion mechanism 40 includes a cylinder 41, a piston 42 that can be inserted into the cylinder 41, and a knockout pin 43 that is connected to the rod of the piston 42 and can press the molding object W. A first fluid chamber 44 is provided on the surface of the piston 42 inserted into the cylinder 41 that faces away from the knockout pin 43 .

[0077] Then, by supplying hydraulic fluid L into the first fluid chamber 44 and pressing the knockout pin 43 toward the molded object W via the piston 42, a force is applied to the knockout pin 43 on the molded object W, thereby enabling the molded object W to be pushed out of the lower mold 18.

[0078] In this embodiment, the cylinder 41 of the extrusion mechanism 40 is provided with a second liquid chamber 45 on the side of the piston 42 facing the knockout pin 43, similar to the cylinder 11 in the first embodiment. In this manner, also in this embodiment, a so-called double-acting cylinder is used as the cylinder 41, in which the first fluid chamber 44 and the second fluid chamber 45 are provided above and below the piston 42, respectively.

[0079] The extrusion mechanism 40 also includes a supply and discharge system for the hydraulic fluid L to the first fluid chamber 44 of the cylinder 41. Specifically, a supply and discharge pipe 46 is connected to the first fluid chamber 44 of the cylinder 41, and a pump 47 is attached to the supply and discharge pipe 46 to supply the working fluid L to the first fluid chamber 44 via the supply and discharge pipe 46. The pump 47 functions as a pressure-boosting mechanism that can increase the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41. In addition, a flow rate adjusting valve 48 and an electromagnetic valve 49 for switching the cylinder operation direction are attached to the supply / discharge pipe 46 between the first fluid chamber 44 of the cylinder 41 and the pump 47 .

[0080] A supply / discharge pipe 50 is connected to the second fluid chamber 45 of the cylinder 41, and a counterbalance valve 51 is provided in the supply / discharge pipe 50. A pressure switching pipe 52 equipped with a pressure switching valve 53, a pressure reducing valve 54, etc. is connected to the counterbalance valve 51, and similar to the counterbalance valve 32 in the first embodiment, when the pressure of the working fluid L in the supply and discharge pipe 50 exceeds the fluid pressure in the pressure switching pipe 52, the working fluid L is discharged from the supply and discharge pipe 50.

[0081] At this time, the pressure switching valve 53 switches the hydraulic pressure in the pressure switching pipe 52 between a predetermined hydraulic pressure and, for example, 0.1 MPa (a hydraulic pressure determined by the pressure reducing valve 54), but as in the first embodiment, it is possible to configure the hydraulic pressure to be switched in stages or continuously between these hydraulic pressures.

[0082] The supply and discharge pipe 50 is also connected to an electromagnetic valve 49 for switching the cylinder operation direction. By switching the solenoid valve 49 for switching the cylinder operating direction, the supply and discharge of the hydraulic fluid L to the supply and discharge pipes 46 and 50 can be switched, thereby switching the operating direction (extending direction and retracting direction) of the piston 42 (knockout pin 43) of the cylinder 41.

[0083] Next, a method for controlling the pressure of the hydraulic fluid L in the first fluid chamber 44 of the cylinder 41 in the molding device 1 according to this embodiment will be described. In the molding device 1 of this embodiment, as in the first embodiment, the pump 47 (pressure-boosting mechanism) increases the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 while the knockout pin 43 is being brought closer to the workpiece W before the knockout pin 43 begins to push out the workpiece W.

[0084] In this case, too, gas is dissolved in the working fluid L of the extrusion mechanism 40, and the relationship between the compression amount ΔV [liter] of the working fluid L and the pressure P [MPa] is similar to the relationship shown in the graphs of Figures 2 and 3. In this case, since the volume of the working fluid L in the first fluid chamber 44 of the cylinder 41 and the supply and discharge pipe 46 is not the aforementioned 220 [liters], at least the numerical scale on the vertical axis of the graph (compression amount ΔV [liters] of the working fluid L) will change, but the tendency for the rate of increase in the compression amount of the working fluid L (dΔV / dP) to decrease as the pressure of the working fluid L increases remains unchanged.

[0085] Therefore, by increasing the pressure of the hydraulic fluid L in the first fluid chamber 44 of the cylinder 41 in advance while the knockout pin 43 is being brought closer to the workpiece W, even if the knockout pin 43 receives a large load from the workpiece W when it begins to press against the workpiece W to extrude it and the pressure of the hydraulic fluid L increases, for the same reasons as explained in the first embodiment, it is possible to quickly perform feedback control, etc., to maintain the position and speed of the knockout pin 43 as set.

[0086] In other words, when the knockout pin 43 receives a large load change from the workpiece W and the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 increases by ΔP, it becomes necessary to supply the working fluid L equivalent to the compressed volume of the working fluid L from the pump 47 to the supply and discharge pipe 46 and the first fluid chamber 44 of the cylinder 41. However, as shown in Figure 5, the supply amount (i.e., the compression amount of the working fluid L) dΔV is less when the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 is increased by ΔP from a pre-existing high pressure state (see Pa in the figure) as in this embodiment than when the pressure of the working fluid L in the first fluid chamber 44 is increased by ΔP from atmospheric pressure (see Pb in the figure).

[0087] The smaller the supply amount of the hydraulic fluid L, the more quickly the supply of the hydraulic fluid L by the pump 47 is completed. Therefore, in this embodiment as well, when the knockout pin 43 receives a large load from the workpiece W, the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 of the extrusion mechanism 40 is increased, and feedback control can be quickly performed to maintain the position and speed of the knockout pin 43 as set.

[0088] As described above, according to the molding device 1 of this embodiment, the pump 47 (pressure-boosting mechanism) is configured to increase the pressure of the working fluid L in the first liquid chamber 44 of the cylinder 41 of the extrusion mechanism 40 while the knockout pin 43 is being brought closer to the workpiece W before the knockout pin 43 begins to press against the workpiece W to extrude it. Therefore, even if the pressure of the working fluid L rises suddenly due to a large load change from the workpiece W when the knockout pin 43 begins to press against the workpiece W to extrude it, it is possible to quickly perform feedback control, etc. to maintain the position and speed of the knockout pin 43 as set, compared to when the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 is increased after pressing against the workpiece W begins.

[0089] In addition, the method of increasing the pressure of the working fluid L in the second fluid chamber 45 can be the same as the method of increasing the pressure of the working fluid L in the second fluid chamber 14 of the cylinder 11 in the first embodiment. In this case, for example, if the pressures of the first and second liquid chambers 44 and 45 are adjusted so that the loads applied to the piston 42 from the first and second liquid chambers 44 and 45 are the same, the loads applied to the piston 12 from the first and second liquid chambers 44 and 45 will be balanced, and the knockout pin 43 can be brought closer to the molded object W by operating the pump 47.

[0090] Furthermore, if the counterbalance valve 51 is configured to be able to switch the pressure of the working fluid L in the supply / discharge pipe 50 or the second fluid chamber 45 of the cylinder 11 in a stepwise or continuous manner, it becomes possible to vary the resistance load applied to the piston 42, and it becomes possible to adjust the load (differential load) applied to the piston 42 by varying it in a stepwise or continuous manner.

[0091] [Third embodiment] On the other hand, by controlling the extrusion mechanism 40 (see Figure 4) of the molding device 1 of the second embodiment using a concept opposite to that of the second embodiment, it is possible to prevent the molded object W from popping out when the molded object W is pushed out of the mold by the knockout pin 43 after molding. To achieve this, after the knockout pin 43 comes into contact with the workpiece W, while the knockout pin 43 is exerting a force on the workpiece W, the pump 47 (pressure-boosting mechanism) increases the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 and also increases the pressure of the working fluid L in the second fluid chamber 45, thereby applying pressure to the piston 42 in the opposite direction to the pressure applied by the working fluid L in the first fluid chamber 44.

[0092] A specific explanation will be given below using the graph in FIG. For example, the pressure of the working fluid L in the second fluid chamber 45 is set to a low pressure (e.g., atmospheric pressure; see Pc in the figure), and the pressure of the working fluid L in the first fluid chamber 44 is increased (see Pd in ​​the figure) to push the workpiece W with the knockout pin 43.

[0093] In this case, when the workpiece W is pushed out of the mold and the load from the workpiece W is suddenly released, the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 suddenly drops from Pd to Pc, causing the working fluid L to suddenly expand. The amount of expansion Δ at that time is the difference between the amount of compression ΔV of the working fluid L at the pressure Pd and the amount of compression ΔV of the working fluid L at the pressure Pc. At this time, the amount of expansion Δ of the hydraulic fluid L is large, so that the knockout pin 43 is pushed out significantly, causing the workpiece W to jump out significantly from the mold.

[0094] In contrast, in this embodiment, after the knockout pin 43 abuts against the workpiece W, while the knockout pin 43 is exerting a force on the workpiece W, as shown in Figure 6, the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 is increased to, for example, Pf, and the pressure of the working fluid L in the second fluid chamber 45 is increased to, for example, Pe.

[0095] Then, when the workpiece W is pushed out of the mold and the load from the workpiece W is suddenly removed, the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 drops from Pf to Pe, causing the working fluid L to expand. However, the expansion amount Δ at that time (the difference between the compression amount ΔV of the working fluid L at pressure Pf and the compression amount ΔV of the working fluid L at pressure Pe) is significantly smaller than the expansion amount Δ when the pressure of the working fluid L in the first fluid chamber 44 drops from Pd to Pc.

[0096] Therefore, by controlling the pressure of the working fluid L in the first fluid chamber 44 of the cylinder 41 and the pressure of the working fluid L in the second fluid chamber 45 as in this embodiment, it is possible to prevent the workpiece W from popping out when the workpiece W is pushed out of the mold by the knockout pin 43 after molding.

[0097] It goes without saying that the present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention. It is also possible to combine two or all of the first to third embodiments. [Explanation of symbols]

[0098] 1 Molding equipment. 11 cylinders 12 pistons 13 1st liquid chamber (liquid chamber) 14 2nd liquid chamber 15 slides 16 Upper mold 17 beds 18 Lower mold 25 Pump (boosting mechanism) 40 Extrusion mechanism 41 cylinders 42 Piston 43 Knockout pin 44 1st liquid chamber (liquid chamber) 45 2nd liquid chamber 47 Pump (boosting mechanism) L Hydraulic fluid P pressure W Object to be molded

Claims

1. A cylinder; a piston insertable into the cylinder; a slide connected to the piston and capable of pressing the object to be molded; a bed facing the slide and capable of pressing the molding object between the bed and the slide; a fluid chamber provided in the cylinder, the fluid chamber being capable of applying a force to the slide in the direction of the bed by supplying hydraulic fluid therein; a pressure increasing mechanism capable of increasing the pressure of the hydraulic fluid in the fluid chamber, the pressure-increasing mechanism increases the pressure of the hydraulic fluid in the liquid chamber while the slide is approaching the molding object before the slide starts to press against the molding object; When the slide receives a load from the molding object, the position of the slide is kept constant. A molding device characterized by:

2. the liquid chamber is provided on a surface of the piston inserted into the cylinder that faces away from the slide, A second fluid chamber is provided in the cylinder on a side of the piston facing the slide, The molding device described in claim 1, characterized in that when the pressure-boosting mechanism increases the pressure of the hydraulic fluid in the liquid chamber while the slide is approaching the molded object, the pressure of the hydraulic fluid in the second liquid chamber is increased, applying a pressure to the piston in the opposite direction to the pressure applied by the hydraulic fluid in the liquid chamber.

3. 3. The molding apparatus according to claim 2, wherein the reverse pressure is released at the stage of clamping the mold for the object to be molded.

4. The molding device according to claim 1, characterized in that the pressure-increasing mechanism releases the pressure increase of the hydraulic fluid in the liquid chamber that was caused while the slide was approaching the molding object after the pressure increase is released from the molding object.

5. A molding apparatus including a slide to which an upper mold can be attached, and a bed facing the slide to which a lower mold can be attached, an extrusion mechanism for extruding the object to be molded from the upper mold or the lower mold after molding; The extrusion mechanism includes: A cylinder; a piston insertable into the cylinder; a knockout pin connected to the piston and capable of pressing the molding object; a fluid chamber provided in the cylinder, into which a hydraulic fluid is supplied so that a force can be applied to the workpiece by the knockout pin; a pressure increasing mechanism capable of increasing the pressure of the hydraulic fluid in the fluid chamber; and the pressure-boosting mechanism increases the pressure of the hydraulic fluid in the liquid chamber while the knockout pin is approaching the molding object before the knockout pin starts to push out the molding object, When the knockout pin receives a load from the workpiece, the position or velocity of the knockout pin is maintained at a set position or velocity. A molding device characterized by:

6. the liquid chamber is provided on a surface of the piston inserted into the cylinder that faces away from the knockout pin, a second fluid chamber is provided in the cylinder on a side of the piston facing the knockout pin, The molding device described in claim 5, characterized in that when the pressure boosting mechanism increases the pressure of the hydraulic fluid in the liquid chamber while the knockout pin is being brought closer to the molded object, the pressure of the hydraulic fluid in the second liquid chamber is increased, thereby applying a pressure to the piston in the opposite direction to the pressure applied by the hydraulic fluid in the liquid chamber.

7. The molding device according to claim 6, characterized in that the pressure of the hydraulic fluid in the liquid chamber and the pressure of the hydraulic fluid in the second liquid chamber are both increased while the knockout pin is applying a force to the molded object.

8. A molding apparatus including a slide to which an upper mold can be attached, and a bed facing the slide to which a lower mold can be attached, an extrusion mechanism for extruding the object to be molded from the upper mold or the lower mold after molding; The extrusion mechanism includes: A cylinder; a piston insertable into the cylinder; a knockout pin connected to the piston and capable of pressing the molding object; a fluid chamber provided in the cylinder, capable of applying a force to the workpiece by supplying a hydraulic fluid therein; a pressure increasing mechanism capable of increasing the pressure of the hydraulic fluid in the fluid chamber; and the liquid chamber is provided on a surface of the piston inserted into the cylinder that faces away from the knockout pin, a second fluid chamber is provided in the cylinder on a side of the piston facing the knockout pin, A molding device characterized in that, while the knockout pin is applying a force to the molded object, the pressure-boosting mechanism increases the pressure of the hydraulic fluid in the liquid chamber and also increases the pressure of the hydraulic fluid in the second liquid chamber, thereby applying a pressure to the piston in the opposite direction to the pressure applied by the hydraulic fluid in the liquid chamber.

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