JP3448232B2 - Molding machine overload prevention device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overload preventing device for a molding machine. A molding machine for molding a thin plate material such as a resin sheet or a sheet metal material includes a table drive system, a hydraulic direct drive system, a screw drive system, and a toggle link drive system. Of these, the toggle link drive type does not cause contamination by oil etc.
Although it has the advantage of high molding speed, it may generate excessive molding force just before the top and bottom dead center of the toggle link, and that excessive molding force may cause damage to the molding die or damage to the molding machine itself. Has become. The present invention relates to an overload prevention device that prevents the generation of such an excessive forming force.

[0002]

2. Description of the Related Art There are the following two conventional techniques as overload preventing devices for molding machines. Conventional Example I is adopted in a part of a hot plate forming machine, and an overload prevention device composed of a hydraulic cylinder is connected between an upper table and a toggle link, and is placed at a position away from the hydraulic cylinder. This is a configuration in which equipment such as a relief valve is installed. In this conventional example I, since the hydraulic cylinder is located immediately above the sheet being formed, if oil leaks from the hydraulic cylinder, it will take a lot of labor and time to contaminate the material and clean the periphery of the table. In addition, peripheral devices such as relief valves cannot be placed in a narrow space immediately above the upper table, so they should be installed away from the table, but this increases the distance between the hydraulic cylinder and the relief valve, resulting in poor responsiveness. . Then, if the response of the hydraulic cylinder is slow, there is a problem that damage to the mold cannot be prevented. In Conventional Example II, a spring type overload prevention mechanism is provided between the upper table and the toggle link to avoid oil contamination, but this is effective for the molding machine itself and a specific molding die. , If the strength of the mold used changed, it was necessary to change the spring force one by one.

[0003]

In view of such circumstances, the present invention has no risk of contamination due to oil leakage, has a high responsiveness, and does not need to be reset every time even if the molding die used changes. The purpose is to provide.

[0004]

In the overload prevention device for a molding machine according to claim 1, the main body frame comprises an upper frame and a lower frame, and a plurality of columns connected to at least one of the frames. In a molding machine in which an upper and lower table is arranged inside a space surrounded by the plurality of columns, and at least one of the upper and lower tables is vertically moved by a toggle link, a connecting portion between the frame and the plurality of columns is It is separated, and the frame and the connecting portions of the plurality of columns are respectively connected by an overload preventing hydraulic clamper. According to a second aspect of the present invention, there is provided an overload prevention device for a molding machine, wherein an accumulator is connected to a load side oil chamber of the hydraulic clamper. According to a third aspect of the present invention, the overload prevention device for a molding machine is characterized in that a relief valve capable of adjusting a set pressure is connected to the load-side oil chamber of the hydraulic clamper. According to a fourth aspect of the present invention, there is provided the overload prevention device for a molding machine according to the first aspect of the present invention, further comprising a gap detector for detecting a gap on the separation surface between the frame and the column.

According to the first aspect of the present invention, when an overload occurs during molding, it is transmitted to the frame via the toggle link and acts on the hydraulic clamper. When the load side pressure in the hydraulic clamper exceeds the set value, the hydraulic clamper expands and a gap is generated between the frame and the column. Then, the upper frame, the toggle link, the upper table and the mold are lifted, and the abnormal load applied to those members is removed. Even if oil leaks from the hydraulic clamper, the connection between the frame and the column to which it is attached is located outside the sheet being formed, so that oil does not drip onto the sheet and the sheet or sheet It does not contaminate parts on the surface through which According to the invention of claim 2, the pressure oil in the hydraulic clamper escapes to the accumulator when an overload is applied,
Absorption of hydraulic oil in the accumulator has a quick response, so damage due to delayed response will not occur. According to the third aspect of the present invention, since the set pressure of the hydraulic clamper can be changed by changing the set pressure of the relief valve, the overload limit value can be easily set according to the change of the strength of the molding die. Claim 4
According to the invention, when a gap is generated between the frame and the column due to an abnormal load, it can be detected by the gap detector. Therefore, it is immediately known that an overload has occurred, and a measure for removing the overload can be taken. Can be taken.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings. First, the overall structure of the sheet forming machine according to the embodiment of the present invention will be described with reference to FIGS. 4 is a side view of the sheet forming machine, FIG. 5 is a front view of the forming machine,
FIG. 6 is a view taken along the line VI of FIG.

In FIGS. 4 to 6, reference numeral 1 denotes a main body frame which is constituted by connecting a lower frame 1A and an upper frame 1B with four columns 1C. The lower ends of the four columns 1C are fixed to the four corners of the lower frame 1A, but the upper ends of the columns 1C and the four corners of the upper frame 1B are separated from each other, as will be described later, and are separated from each other. The part is 4
The book is connected by a hydraulic clamper 40.

An opening is provided in the front-back direction of the main body frame 1 (the traveling direction of the sheet to be molded) so that a sheet conveying device for the sheet to be molded can be inserted, and the mold can be taken out in the left and right directions. An opening is provided. Guide rails 7 are provided on the four columns 1C of the main body frame 1, respectively.
The upper and lower tables 2 and 3 are arranged in the main body frame 1 so as to be vertically moved by being guided by the guide rail 7. Molds 4 and 5 for molding are attached to the tables 2 and 3, respectively.
Reference numeral 6 denotes a sheet conveying device that clamps and conveys the sheet to be molded. Also, the lower frame 1A and the upper frame 1B
Table drive mechanism 1 for driving the upper and lower tables 2 and 3
0 and 30 are attached.

Next, the table drive mechanisms 10 and 30 for the upper and lower tables 2 and 3 will be described. FIG. 7 is a plan view of the sheet forming machine according to the present embodiment, and FIG. 8 is a side view showing the upper and lower table drive mechanisms 10 and 30. 7-8,
Reference numeral 11 is a drive motor for the upper table 2, which is the upper frame 1.
The upper rotary link 1 is attached to the output shaft of the speed reducer 12 fixed to B.
3 is fixed, and one end of an upper reciprocating link 14 is pivotally attached to the tip of the upper rotating link 13. The upper rotary link 13 and the upper reciprocating link 14 constitute a reciprocating crank mechanism. When the upper rotating link 13 rotates, the upper reciprocating link 1
4 is reciprocating.

On the other hand, two upper toggle links 18 are arranged on the upper surface of the upper table 2, and the upper ends thereof are fixed to the two upper driven shafts 17. Reference numeral 19 is a support bracket for the upper driven shaft 17. An upper driven link 15 is coupled to one end of each of the two upper driven shafts 17, and the tips of the upper driven links 15 are coupled to each other by an upper coupling rod 16. Therefore, when the upper rotation link 13 rotates,
The upper reciprocating link 14 reciprocates, the movement is transmitted to the upper driven link 15, and the upper driven shaft 17 is converted into reciprocating rotation according to the rotation angle of the upper rotating link 13. Then, the reciprocating rotation is converted into a bending movement of the upper toggle link 18, and the upper table 2 reciprocates up and down, so that the upper and lower dies can be formed and processed in a sandwiched state.

Next, the table drive mechanism 30 of the lower table 3 will be described. However, the lower table drive mechanism 30 is mounted between the lower frame 1A and the lower table 3, and the mounting direction is inverted upside down relative to the upper table drive mechanism 10, and the lower reciprocating link 34 has a telescopic mechanism. The difference lies only in the provision of the hydraulic cylinder 34A constituting the above, and the other points are substantially the same. Therefore, the corresponding members will be compared with the table below and detailed description thereof will be omitted.

Comparison table Upper table drive mechanism 10: Lower table drive mechanism 30 Upper drive motor 11: Lower drive motor 31 Upper reduction gear 12: Lower reduction gear 32 Upper rotation link 13: Lower rotation link 33 Upper reciprocal link 14: Lower reciprocating link 34 Upper driven link 15: Lower driven link 35 Upper connecting rod 16: Lower connecting rod 36 Upper driven shaft 17: Lower driven shaft 37 Upper toggle link 18: Lower toggle link 38 As described above, lower table 3 Also, the lower table drive mechanism 30 can be driven up and down.

The lower table drive unit 30 is provided with an expansion / contraction mechanism as described above. This expansion / contraction mechanism has a hydraulic cylinder 34A interposed in the lower reciprocating link 34, or the lower reciprocating link 34 itself is hydraulically operated. The cylinder 34A is used as a substitute. Then, in a normal molding operation, the hydraulic cylinder 34A is in a contracted state, and when the hydraulic cylinder 34A is extended when the mold is taken out, the lower table 3 is further lowered below the normal open state so that the mold can be taken out easily. be able to.

Next, details of the overload prevention device will be described. FIG. 1 is a hydraulic circuit diagram of an overload prevention device according to an embodiment of the present invention, FIG. 2 (A) is a plan view of a hydraulic clamper portion, (B) is a front view thereof, and FIG. 3 (A). The figure is a side view of the hydraulic clamper part, and the figure (B) is a sectional view taken along the line III-II of FIG. 2 (B).

As shown in FIGS. 2-3, the upper frame 1B
The mounting seats 21 are fixed to the lower surfaces of the four corners of the column 1.
The mounting seat 22 is also fixed to the upper end of C. These mounting seats 21 and 22 are not joined and can be separated, and are fastened to each other by a hydraulic clamper 40 described later.

U-shaped notches 23 in plan view are formed from the upper end surfaces of the four corners of the upper frame 1B to the mounting seats 21 at the lower end and further to the mounting seats 22 at the upper end of the column 1C. A recess 24 larger than the cutout 23 is formed on the lower surface of the mounting seat 22 at the upper end of the pillar 1C.
Are formed.

Two key grooves 25 and 26 are formed in the orthogonal direction on the lower surface of the mounting seat 21 and the upper surface of the mounting seat 22, and the keys 27 and 28 are inserted into the respective key grooves 25 and 26. ing. Therefore, even if the upper frame 1B floats and a slight gap is formed between the mounting seats 21 and 22, a center misalignment in the front-rear and left-right directions between the upper frame 1B and the column 1C does not occur.

On the upper surfaces of the four corners of the upper frame 1B,
The cylinder 41 of the hydraulic clamper 40 for preventing overload is fixed. Piston rod 4 of this hydraulic clamper 40
The reference numeral 2 extends downward through the cutout portion 23, and the flange 43 at the lower end thereof is located in the recess 24 and abuts the lower surface of the mounting seat 23. In the normal state, the upper frame 1B and the column 1C are firmly fastened by the hydraulic clamper 40.

A known displacement detector 61 is attached to the side surface of the upper frame 1B, and the support rod 1C is attached to the detection rod.
The contact plate 62 attached to the side is in contact. The displacement detector 61 and the contact plate 62 constitute a gap detector as claimed in claims. When the space between the mounting seat 21 and the mounting seat 22 floats, the displacement detector 61 can detect that there is a gap.

As shown in FIG. 1, four hydraulic clampers 4 are provided.
The load-side oil chamber 45 of 0, that is, the oil chamber on the piston rod side of the oil chamber partitioned by the piston 44 is connected to the upper frame 1B via the toggle link when the molding load becomes excessive.
Can be lifted, so the pressure rises. An accumulator 50 is connected to the load side oil chamber 45 via an oil passage 51. Further, the accumulator 50 has an oil passage 5
A pump 53 for supplying hydraulic oil is connected via 2, and a relief valve 54 and a pressure switch 55 are connected to this oil passage 52. The relief valve 54 can freely adjust the set pressure, and the working oil having the set pressure can be stored in the load oil measuring chamber 45 of the hydraulic clamper 40. When the set pressure is exceeded, the relief valve 54 opens and the pressure is increased. Oil can escape to the tank. The pressure switch 55 is provided to start the pump 53 and supply pressure oil when the hydraulic oil pressure becomes equal to or lower than the lower limit value.

The relief valve 54 is provided apart from the hydraulic clamper 40 for convenience of setting a relief pressure and as a countermeasure against oil leakage, and is provided, for example, on the machine side where an operator can easily approach, but the four accumulators 50 are provided. Hydraulic clamper 40
Is installed at a recent distance, for example, on the upper surface of the upper frame 1B. Since the accumulator generally has no delay in absorption of hydraulic oil, and the oil passage 51 between the four hydraulic clampers 40 is short, when the pressure in the load side oil chamber 45 of the hydraulic clamper 40 becomes excessive, the accumulator can be quickly operated. The excess pressure oil can be absorbed by the accumulator 50. Therefore, since the response of the excessive pressure oil absorption is fast, it is possible to more reliably prevent damage to the mold and the molding machine.

Next, the overload preventing action of this embodiment will be described. If an overload occurs during the forming of a sheet between the upper table 2 and the lower table 3 shown in FIG. 4 or if a load greater than the set value occurs due to an initial setting error, this load is changed by the toggle link 18 (see FIG. 8). ) Via the upper frame 1B
Then, the upper frame 1B tries to surface. The lift of the upper frame 1B is caused by the hydraulic clamper 40 shown in FIG.
Since the pressure in the load-side oil chamber 45 is increased,
The pressure oil in 5 escapes to the accumulator 50 by the amount of pressure increase. In this case, the relief valve 54 is also opened, and the pressure oil also starts to escape to the tank from there, but the relief valve 54 does not respond instantly, so that it takes time to eliminate the overload. However, in the present invention, the accumulator 50 instantly absorbs the overpressure oil, so that the upper frame 1B floats immediately in response to the occurrence of overload. Then, when the upper frame 1B floats, the toggle link 18, the upper table 2, and the upper mold 4 also float together, so that the abnormal load applied to these members is removed.

As described above, when the upper frame 1B floats, the gap between the upper frame 1B and the support 1C also widens,
Since this gap is constantly monitored by the displacement detector 61, it is immediately apparent to the operator that an abnormal load is acting, and the operator can immediately take actions such as stopping the work and correcting the settings.

In the overload prevention device of the present embodiment, the pressure oil in the hydraulic clamper 40 at the time of overloading acts on the hydraulic clamper 40.
Since it is instantly absorbed by the accumulator 50 arranged in the vicinity of the inside, the response is quick, and therefore, the mold or the like is not damaged due to the response delay. Further, since the hydraulic clampers 40 are attached to the four corners of the upper frame 1B and are located outside the formed sheet, the sheet will not be contaminated even if oil leaks. Although the hydraulic clamper is provided between the upper frame 1B and the column 1C in the above embodiment, it may be provided between the lower frame 11A and the column 1C.

[0025]

According to the first aspect of the present invention, when an overload occurs during molding, the hydraulic clamper expands and the upper frame floats, and the upper table and the upper mold connected to the hydraulic frame also float and the frame A gap is generated between the pillar and the abnormal load is removed. Even if there is oil leakage from the hydraulic clamper, it is located outside the sheet being formed, so the oil does not drip onto the sheet and may contaminate the sheet or parts on the surface through which the sheet passes. Absent. According to the second aspect of the present invention, the pressure oil in the hydraulic clamper escapes to the accumulator when an overload is applied, but the response is quick and therefore damage due to delay in response does not occur. According to the third aspect of the invention, since the set pressure of the hydraulic clamper can be changed by changing the set pressure of the relief valve, it is possible to easily set the overload limit value according to the change of the strength of the molding die. According to the invention of claim 4, when a gap is generated between the frame and the support column due to an abnormal load, it can be detected by the gap detector, so that the overload removal process can be performed quickly.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of an overload prevention device according to an embodiment of the present invention.

2A is a plan view of a hydraulic clamper portion, and FIG. 2B is a front view thereof.

3A is a side view of a hydraulic clamper portion, and FIG. 3B is a sectional view taken along the line III-III in FIG. 2B.

FIG. 4 is a side view of the sheet forming machine.

FIG. 5 is a front view of the molding machine.

FIG. 6 is a view taken along line VI in FIG.

FIG. 7 is a plan view of the sheet forming machine according to the present embodiment.

FIG. 8 is a side view showing the upper and lower table drive mechanisms 10 and 30.

[Explanation of symbols]

1B upper frame 1C prop 2 Upper table 3 lower table 4 Upper mold 5 Lower mold 40 hydraulic clamper 50 accumulator 54 relief valve

Claims (4)

(57) [Claims] 1. A body frame comprises an upper frame and a lower frame, and a plurality of columns connected to at least one of the frames, and an upper and lower table is arranged inside a space surrounded by the plurality of columns. In the molding machine in which at least one of the upper and lower tables is vertically moved by a toggle link, the frame and the plurality of columns are separated from each other, and the frame and the plurality of columns are connected to each other. An overload prevention device for a molding machine, characterized in that each is connected by a hydraulic clamper for preventing overload. 2. An overload preventing device for a molding machine according to claim 1, wherein an accumulator is connected to a load side oil chamber of said hydraulic clamper. 3. The overload prevention device for a molding machine according to claim 2, wherein a relief valve capable of adjusting a set pressure is connected to the load side oil chamber of said hydraulic clamper. 4. The overload prevention device for a molding machine according to claim 1, further comprising a gap detector for detecting a gap on a separation surface between the frame and the column.