EP0546249A2

EP0546249A2 - Pressing machine

Info

Publication number: EP0546249A2
Application number: EP92111480A
Authority: EP
Inventors: Tadayoshi Uehara
Original assignee: Aida Engineering Ltd
Current assignee: Aida Engineering Ltd
Priority date: 1991-11-13
Filing date: 1992-07-07
Publication date: 1993-06-16
Also published as: EP0546249A3

Abstract

Disclosed is a pressing machine for working a material by a top tool secured to a slide unit connected via a con'rod to a crank shaft and by a bottom tool secured to a bolster. The pressing machine includes a slide unit (12) connected via a con'rod (10) to an eccentric unit (9) of a crank shaft (8); slide horizontal position adjusting devices (42), so mounted on a frame of the pressing machine as to confront respective slide members of the slide unit (12) in the horizontal direction, for adjusting positions of the respective members of the slide unit (12); and a slide lifter (11), provided between the slide unit (12) and the con'rod (10), for making the slide unit (12) ascendable and descendable with respect to the con'rod.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a pressing machine for working a material by causing a slide to move up and down with rotations of a crank shaft.

Related Background Art

A pressing machine is constructed such that: a slide connected via a con'rod to a crank shaft is moved up and down with rotations of the crank shaft; and a material is worked by a top tool secured to the slide and a bottom tool secured to a bolster. In this type of pressing machine, a slide guide is provided on a column for joining a bed to a crown. The slide makes the up-and-down motions while being guided by this slide guide. Further, a guide post is provided in a die unit composed of the upper and bottom tools. The top tool is guided by this guide post with respect to the bottom tool, thus making the vertical motions.
There are scatters in thickness and in hardness of the material undergoing a press working. For this reason, a horizontal thrust load acts on the top tool and the slide as reaction from the material when working the material with a descent of the slide. This thrust load has hitherto been received by the slide guide and the guide post. With this arrangement, a molding accuracy of a molded product is obtained by hindering horizontal movements of the slide and the top tool as well. This prior art is, however, conceived as a passive means for obviating the problem with the intention of hindering the horizontal movements of the top tool and the slide due to the thrust load by the elastically deformed slide guide and guide post. It is difficult to form a molded product at a higher accuracy than a constant accuracy.
Further, in a progressive work pressing machine for working the material sequentially at a plurality of working stages by intermittently feeding the material, a plurality of die units are fitted to one slide. Hence, when working the material by the plurality of top tools in combination with the plurality of bottom tools secured to the bolsters with a descent of the slide, and if the thrust load acts on the single top tool, this thrust load is transferred via the slide to other top tools. For this reason, the top tools exert adverse influences on each other. As a result, it is difficult to attain the high accuracy molding of the molded product. Besides, if the thrust load acts on the top tool, it follows that the top tool works the material with a core deviation from the bottom tool. The top and bottom tools undergo a large frictional force. This results in such a problem that a life-span of the die is reduced.
Still further, in the progressive work pressing machine, the material is simultaneously worked by the top and bottom tools on the respective working stages when the slide reaches a bottom dead center. Hence, a molding load of the pressing machine increases. This also conduces to such a problem that vibrations and noises caused by the pressing machine augment.
In addition, the pressing machine requires a slide adjusting operation when the height dimension of the top or bottom tool varies at replacement of the die and also a slide adjusting device for effecting a bottom dead center compensating operation when the bottom dead center of the slide changes in the case of a thermal expanding deformation of the slide due to press working heat. At the same time, the pressing machine needs a breakthrough countermeasure device for reducing the vibrations and noises caused in the pressing machine when punching out the material with the top tool. These devices have hitherto been provided as separate devices in the pressing machine. A structure of the pressing machine becomes complicated, correspondingly.

SUMMARY OF THE INVENTION

It is a primary object of the present invention to provide a pressing machine capable of press-working a material while ensuring an alignment between top and bottom tools by positively hindering horizontal movements of the top tool and a slide due to a thrust load during working of material.
It is another object of the present invention to provide a pressing machine capable of increasing a molding accuracy of a molded product by preventing the thrust load from being transferred to other top tools and the top tools from exerting adverse influences on each other even when the thrust load acts on the top tool at one working stage in the case of preparing a plurality of top tools corresponding to the respective working stages.
It is still another object of the present invention to provide a pressing machine capable of decreasing the molding load and therefore reducing the vibrations and noises.
It is a further object of the present invention to provide a pressing machine capable of attaining a simplified structure by eliminating the necessity for preparing a slide adjusting device and a breakthrough countermeasure device as separate devices.
It is a still further object of the present invention to provide a slide horizontal position adjusting device without adding any modification to the respective inventions described above.
In a pressing machine for working a material by a top tool secured to a slide connected via a con'rod to a crank shaft and by a bottom tool secured to a bolster, a pressing machine according to the present invention is constructed such that: the crank shaft is formed with a plurality of eccentric members with an angular phase difference; a plurality of slide members independently separated from each other are connected via the con'rods to these eccentric members; a pressing machine frame is mounted with slide horizontal position adjusting devices, so disposed as to confront these slide members in the horizontal direction, for adjusting the horizontal position of the slide unit; and a slide lifter for making the slide member ascendable and descendable with respect to the con'rod is provided between the slide member and the con'rod.
As one example, the slide horizontal position adjusting device is constructed of: position detecting sensors for detecting positions of the members of the slide unit in the two orthogonal horizontal directions; a plurality of pads attached to the frame of the pressing machine with slight gaps from the four perpendicular surfaces of the members of the slide unit which face in the two orthogonal horizontal directions, the pads causing pressures of supplied pressure oils to act on the perpendicular surfaces; and control valves, provided in a hydraulic circuit for supplying the pressure oil to the pads, for setting the slide unit in a proper horizontal position by regulating the supply of the pressure oils to the respective pads in accordance with the slide horizontal position detected by the position detecting sensors.
Further, as one example, the slide lifter is constructed of: a hydraulic cylinder fixed to an upper end of the slide unit; a vertically movable pressure receiving member including a piston portion for sectioning an internal chamber of the hydraulic cylinder into an upper and lower chambers, the pressure receiving member having its upper part, protruded from the hydraulic cylinder, to which a lower part of the con'rod is connected; and changeover valves, provided in a connection circuit for connecting the upper and lower chambers, for flowing the pressure oil of the lower chamber into the upper chamber.
Additionally, a pressing machine according to the present invention is provided with a single slide member and only the slide horizontal position adjusting device or only the slide lifter.
In a pressing machine provided with a plurality of slide members, the respective slide members are connected via the con'rods to the crank shaft eccentric members with an angular phase difference. Hence, these slide members move up and down at timings which deviate corresponding to the angular phase difference. There is caused a deviation in the timings at which the material is worked by the top and bottom tools. The material is not worked simultaneously with descents of the slide members. Therefore, the molding load of the pressing machine is reduced.
Besides, the respective slide members are independently separated from each other. Hence, even when the thrust load acts on the top tool on the single working stage, the top tools secured to these slide members do not exert adverse influences on each other. Further, the horizontal positions of the individual slide members are adjusted by the slide horizontal position adjusting devices. Therefore, the core deviation between the top and bottom tools is obviated, and the material is thus worked. A molded product is formed at a high accuracy by effecting the automatic core-adjustment between the top and bottom tools with the slide horizontal position adjusting devices during working of the material. Besides, the life-span of the dies also increases.
Moreover, the slide members are raised and lowered by the slide lifters with respect to the con'rods, thereby performing the slide adjusting operation and the slide bottom dead center compensating operation as well. In addition, it is possible to reduce the vibrations and noises in the breakthrough by operating the slide lifters when punching out the material.
In the pressing machine equipped with the single slide member and only the slide horizontal position adjusting device, the core-deviation between the top and bottom tools can be obviated by the slide horizontal position adjusting device. Furthermore, in the pressing machine equipped with only the slide lifter, the slide adjusting operation and the slide bottom dead center compensating operation can be performed by the slide lifter. Besides, it is feasible to attain reductions in the vibrations and noses in the breakthrough.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent during the following discussion taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front elevation illustrating a whole pressing machine in accordance with an embodiment of the present invention;
FIG. 2 is a partially sectional front view illustrating a slide unit;
FIG. 3 is a sectional view taken substantially along the line III-III of FIG. 2, showing the same unit including a hydraulic circuit;
FIG. 4 is a perspective view depicting a configuration of the slide unit as a whole;
FIG. 5 is a view of assistance in explaining the action to eliminate a core-deviation between top and bottom tools by a slide horizontal position adjusting device;
FIG. 6 is a partially sectional view illustrating a slide lifter including the hydraulic circuit;
FIG. 7 is a front elevation showing a pressing machine provided with the single slide member and the slide horizontal position adjusting device but with no slide lifter; and
FIG. 8 is a front elevation illustrating a pressing machine provided with the single slide member and the slide lifter but with no slide horizontal position adjusting device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will hereinafter be described with reference to the accompanying drawings.
Referring to FIG. 1, a motor 3 is mounted on a crown 2 of a pressing machine 1. A driving force of the motor 3 is transferred via a belt 4, a flywheel 5 and a clutch 6 to a crank shaft 8 fitted with a brake 7. An eccentric unit 9 consisting of totally three pieces of eccentric members 9A, 9B, 9C is provided on the crank shaft 8 axially rotatably supported in an interior of the crown 2. Upper portions of con'rods 10 are rotatably fitted to the eccentric unit 9. A slide unit 12 is connected through a slide lifter 11 to lower portions of the con'rods 10. The slide unit 12 includes, as similar to the eccentric unit 9, totally three pieces of slide members 12A, 12B, 12C. These slide members are independently separated from each other.
The eccentric members 9A, 9C are formed with the same angular phase in the circumferential direction of the crank shaft 8. The eccentric member 9B is, however, formed with an angular phase advanced in the rotating direction of the crank shaft 8 with respect to these eccentric members 9A, 9C. For this reason, there is a difference in the angular phase between the eccentric members 9A, 9C and the eccentric member 9B. When the crank shaft 8 rotates, the slide member 12B reaches a bottom dead center first. The slide members 12A, 12C reaches the bottom dead center second.
Top tools 13 are secured to the lower surfaces of the respective members of the slide unit 12. Bottom tools 15 corresponding to the top tools 13 are secured to an upper surface of a bolster 14. These top tools and bottom tools, 13, 15 are combined to constitute working stages A, B, C for effecting progressive-working on a material 16. The material 16 composed of a coil material is intermittently fed by a feed roller device 17 every time the slide unit 12 moves up and down. The material 16 is worked sequentially by the top tools 13 and the bottom tools 15 on the respective working stages A, B, C. The top tools 13 and the bottom tools 15 in this embodiment are dies and punches for punching out the material 16.
When the crank shaft 8 is rotated by the driving force given from the motor 3 depicted in FIG. 1, the slide members 12A, 12B, 12C are caused to move up and down by the eccentric members 9A, 9B, 9C through the con'rods 10. The eccentric member 9b has the angular phase difference advanced in the rotating direction of the crank shaft 8, and hence the slide member 12B reaches the bottom dead center first. The material 16 is thus punched out. Subsequently, the slide members 12A, 12C come to the bottom dead center, whereby the material 16 is punched out. Therefore, it follows that working timings of the material 16 on the respective working stages A, B, C deviate from each other.
Thus, the working operations of the material 16 on the working stages A, B, C are not performed simultaneously. Hence, a molding load of the pressing machine is not a total of working loads on the working stages A, B, C. In accordance with this embodiment, the molding load is a total of the working loads on the two working stages A, C, resulting in a reduction in the molding load. For this reason, in accordance with this embodiment, it follows that vibrations and noises of the pressing machine which are caused when working the material 16 are decreased.
Referring to FIG. 4, the slide unit 12 is constructed of a circular platen 19 encased in a lower box-like case 18 and a guide member 20 standing erect from the platen 19. The guide member 20 assuming a cross in plane includes a forward extending portion 20A, a backward extending portion 10B, a leftward extending portion 20C and a rightward extending portion 20D which extend in back-and-forth directions and in right-and-left directions. These extending portions 20A, 20B, 20C, 20D have, as illustrated in FIG. 3, surfaces, 21, 22, 23, 34, 25, 26, 27, 28 by twos which are directed opposite to each other. The surfaces 25, 28, the surfaces 26, 27, the surfaces 21, 24 and the surfaces 22, 23 shape four perpendicular surfaces D, F, E, F, G on the slide unit 12, which face in orthogonal horizontal directions, i.e., in the back-and-forth directions and in the right-and-left directions.
A frame 29 of the pressing machine 1 is fitted with pads 30 confronting the surfaces 21 - 28 with slight gaps therebetween. These pads 30 are supplied with a high pressure oil from a hydraulic source 31 via a hydraulic circuit 32. The pressures of the pressure oil supplied to the respective pads 30 act on the surfaces 21 - 28. The pressure oil is supplied in common from a branch circuit of the hydraulic circuit 32 to the two pads 30 shown in FIG. 3 and confronting the two surfaces among the surfaces 21 - 28, these two surfaces forming one perpendicular surface among the four perpendicular surfaces D - G.
To explain concretely, the pressure oil is supplied from a branch circuit 32A of the hydraulic circuit 32 to the two pads 30 confronting the surfaces 25, 28 which form the perpendicular surface D facing frontwards in the to-and-fro directions. The pressure oil supplied from a branch circuit 32B of the hydraulic circuit 32 to the two pads confronting the surfaces 26, 27 which form the perpendicular surface E facing backwards in the to-and-fro directions. Similarly, the pressure oils are supplied from branch circuits 32C, 32D to two pairs of pads 30 respectively confronting the surfaces 21, 24 and the surfaces 22, 23 which form the perpendicular surfaces F, G facing bilaterally in the right-and-left directions.
In accordance with the embodiment, as illustrated in FIG. 4, the pads 30 are provided at upper and lower two stages. With this arrangement, the pressure oils are actually supplied in common to the four pads 30 from one branch circuit.
As depicted in FIG. 3, the branch circuits 32A - 3D are provided with control valves 33 - 36. These control valves 33 - 36 are ON/OFF-operated by electric signals transmitted from an unillustrated control unit. In the case of an ON operation, the pressure oil is supplied to the pads 30. Whereas in an OFF operation, the pressure oil from the hydraulic circuit escapes into a tank 37. Further, the control valves 33 - 36 are high-respondency valves each exhibiting a very high OFF-switching speed; and the OFF operation can be executed many times within a short time.
The control valves 33 - 36 are normally ON-operated. Hence, the pressure oil having the same pressure is supplied to all the pads 30. The slide unit 12 is in a constant position in the to-and-fro directions and in the right-and-left directions owing to a pressure balance between the pressure oils. Besides, the slide unit 12 does not rotates about a vertical shaft. When one of the control valves 33 - 36 is OFF-operated, no pressure oil is supplied to the pad 30 connected to this control valve during this OFF operation. The pressure balance between the pressure oils is thereby lost, with the result that a horizontal thrust force toward the pads 30 supplied with no pressure oil is caused in the slide unit 12. If the control valve is OFF-operated many times within the short time, the slide unit 12 moves largely in the horizontal direction. A moving quantity of the slide unit 12 can be set by the number of OFF-operations of the control valve.
As described above, the control valves 33 - 36 are intended to prescribe the supply of the pressure oil to the pads 30. The position of the slide unit 12 can be properly modified to a horizontal position by the ON/OFF switching operations of these control valves 33 - 36.
The pressure oil supplied to the respective pads 30 flows out of the slight gaps between the surfaces 21 - 28 of the slide unit 1 and the pads 30 shown in FIG. 5. The effluent pressure oil drops down onto the upper surface of the platen 19. As illustrated in FIG. 4, a side wall 19A is formed along the outer peripheral edge of the platen 19. An oil receptacle 39 is formed on the upper portion of the platen 19. The oil is therefore reserved in the oil receptacle 39 and fed back to the tank via an oil suction collecting circuit connected to the platen 19.
Attached, as depicted in FIG. 3, to the frame 29 of the pressing machine 1 are a back-and-forth position detecting sensor 40 and a right-and-left position detecting sensor 41 which confront in the horizontal direction with gaps from the backward extending portion 20B and the leftward extending portion 20C of the slide unit 12. These sensors 40, 41 detect a back-and-forth position and a right-and-left position of the slide unit 12. Transmitted from the sensors 40, 41 to the control unit are electric signals of the detected back-and-forth and right-and-left positions of the slide unit 12. Based on the electric signals, the control unit transmits electric signals to effect ON/OFF changeovers of the control valves 33 - 36.
As explained above, a slide horizontal position adjusting device 42 for adjusting two positions of the slide unit 12 in orthogonal horizontal directions is constructed of the pads 30 so provided on the frame 29 of the pressing machine 1 as to confront the slide unit 12 in the horizontal direction, the back-and-forth position detecting sensor 40 and the right-and-left position detecting sensor 41. This slide horizontal position adjusting device 42 is constructed to include the control valves 33 - 36 and the control unit as well.
As illustrated in FIG. 2, the frame 29 of the pressing machine 1 is also mounted with a height position detecting sensor 43 for detecting a height position of the slide unit 12. This sensor 43 is mounted on the frame 29 with a gap from the rightward extending portion 20D of the guide member 20 of the slide unit 12 in accordance with this embodiment. An electric signal, transmitted from the sensor 43, of the height position of the slide unit 12 is inputted to the control unit.
The respective members of the slide unit 12 make the vertical motions while the pressures of the pressure oils from the respective pads 30 act on the surfaces 21 - 28 of the guide member 20, assuming the cross in plane, of the slide unit 12. Normally, all the control valves 33 - 36 are ON-operated, and hence the slide unit 12 is in the constant position in the back-and-forth directions and in the right-and-left directions with the pressure balance of the pressure oils from the respective pads 30. In this state, the slide unit moves up and down.
As illustrated in FIG. 5, when the top tool 13 punches out the material 16 in combination with the bottom tool 15, and if there are scatters in thickness and in hardness of the material 16, for instance, a leftward thrust load W₁ acts on the top tool 13 as reaction from the material 16. The top tool 13 and the slide unit 12 move left to cause an eccentric quantity e due to this thrust load W, . This movement of the slide unit 12 is detected by the right-and-left position detecting sensor 41 shown in FIG. 3. Based on the electric signal transmitted from this sensor 41, the control unit performs the OFF operation of the control valve 36 for a short period of time. Lost consequently is the lateral pressure balance between the pressure oils from the pads 30 which act on the slide unit 12. A rightward thrust load W₂ shown in FIG. 5 acts on the slide unit 12. The slide unit 12 is thrust back rightwards by this thrust load W₂, resisting the thrust load W_i. The material 16 is thereby punched out by the top and bottom tools 13, 15 in such an alignment state as to obviate the eccentric quantity e. If the thrust load W₁ is large, the control valve 36 is repeatedly ON/OFF-operated, thereby ensuring the alignment state between the top and bottom tools 13, 15.
Therefore, the top and bottom tools 13, 15 punch out the material 16 with no core deviation, and a molding accuracy of a molded product out of the material 16 increases. In addition, the top tool 13 is automatically core-adjusted and fitted to the bottom tool 15 in this manner, whereby these tools 13, 15 do not frictionally contact each other. It is therefore possible to prevent a reduction in the lifetime of the tools 13, 15.
Further, the three slide members 12A, 12B, 12C are independently separated from each other. Hence, even when the thrust load W₁ acts on the top tool 13 on a certain working stage, this thrust load W₁ is not transferred to the top tools 13 on other working stages. Accordingly, the tools 13 on the respective working stages A, B, C exert no adverse influence on each other. The top and bottom tools 13, 15 on the individual working stages A, B, C are automatically core-adjusted by the slide horizontal position adjusting device 42 provided in each of the slide members 12A, 12B, 12C. Then, the material 16 is worked, thereby enhancing the molding accuracy of the molded product.
Note that the automatic core-adjustment for aligning the top and bottom tools 13, 15 may be performed after the above-described sensors have detected the movements of the slide unit 12 and the top tool 13 due to the thrust load W₁ during the punch-out of the material 16 as explained before. Alternatively, the horizontal position of the slide unit 12 is constantly detected by the sensor before punching out the material 16 by the top and bottom tools 13 and 15, whereby the automatic core-adjustment may be executed based on the detection of the core deviation quantity e.
FIG. 6 illustrates the slide lifter 11 provided between the slide member and the con'rod 10 shown in FIGS. 1 and 2. This slide lifter 11 constructed of a hydraulic cylinder 44 fixed to an upper end of the slide unit 12 and a vertically movable pressure receiving member 45 for receiving a hydraulic pressure in the hydraulic cylinder 44. A piston portion 46 is provided in the lower part of the pressure receiving member 45. An internal chamber of the hydraulic cylinder 44 is sectioned by this piston portion 46 into an upper chamber 47 and a lower chamber 48. The stepped piston portion 46 consists of an upper large-diameter portion 46A and a lower small-diameter portion 46B. The upper chamber 47 in which the large-diameter portion 46A makes vertical motions has a large area. The lower chamber 48 in which the small-diameter portion 46B makes the vertical motions has a small area. An upper portion 45A of the pressure receiving member 45 protrudes upwards from the hydraulic cylinder 44. A lower portion of the above- mentioned con'rod 10 is rotatably connected via a wrist pin 49 to this upper portion 45A.
Hydraulic circuits 50, 51 extending from the hydraulic source 31 are connected to the upper and lower chambers 47, 48. The hydraulic circuit 50 is provided, from the upstream side, with a first changeover valve 52 and a first variable throttle valve 53. The hydraulic circuit 51 is provided, from the up stream side, with a pressure-Oreducing valve 54 and a second variable throttle valve 55. A connection circuit 56 for connecting the upper chamber 47 to the lower chamber 48 is interposed between the hydraulic circuits 50, 51. This connection circuit 56 is provided with a second changeover valve 57. The circuits 50, 56 are opened and closed by ON/OFF operations of the first and second changeover valves 52, 57. The ON/OFF operations of these valves 52, 57 are performed automatically by the control unit or by manual operations. Especially, the second changeover valve 57 is operated based on the electric signal of the height position of the slide unit 12, which is transmitted from the height position detecting sensor 43 to the control unit.
The supply of the hydraulic pressure into the hydraulic cylinder 44 from the hydraulic source 31 involves the following steps. The first and second changeover valves 52, 57 are operated to close the hydraulic circuit 50 and the connection circuit 56. Thereafter, when the high pressure oil is fed from the hydraulic source 31, this pressure oil is depressurized down to a predetermined pressure by the pressure-reducing valve 54. Then, the pressure oil is supplied via the hydraulic circuit 51 to the upper chamber 47, and the pressure receiving member 45 is lowered down to a decent limit by the hydraulic pressure. Subsequently, the first changeover valve 52 is ON-operated to open the hydraulic circuit 50. Then, the high pressure oil from the hydraulic source 31 is fed via the hydraulic circuit 50 to the lower chamber 48. A pressure of the pressure oil supplied to this lower chamber 48 is not the depressurized by the pressure-reducing valve 54, and hence, even when the area of the lower chamber 48 is smaller than that of the upper chamber 47, the pressure receiving member 45 is raised by the hydraulic pressure within the lower chamber 48. The pressure oil forced out from the upper chamber 47 returns to the tank 37 from the pressure reducing valve 54. After the pressure receiving member 45 has been raised by a predetermined quantity, the first changeover valve 52 is OFF-operated to close the hydraulic circuit 50. The upper chamber 47 is thereby filled with the lower pressure oil, while the lower chamber 48 is filled with the high pressure oil.
Thereafter, the second changeover valve 57 is ON-operated to open the connection circuit 56. Then, the pressure oil of the lower chamber 48 flows into the upper chamber 47 via the connection circuit 56, whereby the pressure receiving member 45 is lowered. When the second changeover valve 57 defined as a high-respondency control valve is ON/OFF-operated many times, a good deal of pressure oil flows into the upper chamber 47. It follows that the pressure receiving member 45 is descended corresponding to a large stroke. A descent quantity of the pressure receiving member 45 can be determined by the number of ON/OFF operations of the second changeover valve 57.
Consequently, the slide unit 12 is raised and lowered by the slide lifter 11 with respect to the con'rod 10. It is therefore possible to perform the slide adjusting operation for determining the height position of the slide unit 12 in accordance with height dimensions of the top and bottom tools 13, 15. It is also feasible to effect a bottom dead center compensating operation when the bottom dead center of the slide unit 12 fluctuates in the case of a thermal expanding deformation of the slide unit 12 due to the press working heat. Hence, the slide lifter 11 incorporates a function as a slide adjuster capable of performing such operations.
As discussed above, the ascending and descending motions of the slide unit 12 with respect to the con'rod 10 are carried out by the influx of the pressure oil of the lower chamber 48 into the upper chamber 47 via the connection circuit 56 provided with the second changeover valve 57. For this purpose, the slide lifter 11 is constructed to include the connection circuit 56 and the second changeover valve 57 as well.
The slide lifter 11 make the following action in addition to the slide adjusting operation and the slide bottom dead center compensating operation.
Even when the top tool 13 contacts the material 16 upon a descent of the slide unit 12, the material 16 is not immediately punched out. An upward compressing force acts on the con'rod 10 due to working reaction from the material 16. A column 59 for joining the crown of the pressing machine 1 shown in FIG. 1 to a bed 58 is deformed in stretch. An elastic energy is accumulated in this column 59. The crank shaft 8 goes on rotating, and the slide unit 12 reaches a height level just before punching out the material 16. Then, this height level is detected by the height position detecting sensor 43 illustrated in FIG. 2. Based on the electric signal from the sensor 43, the control unit transmits a signal to open the connection circuit 56 by ON-operating the second changeover valve 57. At this moment, the pressure of the pressure oil in the lower chamber 48 is high due to a downward thrust force of the pressure receiving member 45. Therefore, when the second changeover valve 57 is ON-operated, the pressure oil of the lower chamber 48 flows into the upper chamber 47 via the connection circuit 56. A flow rate of the pressure oil at this time is restricted by the variable throttle valves 53, 55.
The elastic energy accumulated in the column 59 is thereby converted into a flow speed energy of the pressure oil forced out by the pressure receiving member 45 from the lower chamber 48 into the upper chamber 47 and simultaneously into an exothermic energy in the variable throttle valves 53, 55. For this reason, when the top tool 13 punches out the material 16, the elastic energy accumulated in the column 59 does not become an energy to cause large vibrations and noises of the pressing machine 1 due to rapid descents of the slide unit 12 and the top tool 13. A breakthrough of the pressing machine 1 during the punch-out is reduced. Hence, the slide lifter 11 has a function as a breakthrough countermeasure device.
The second changeover valve 57 is OFF-operated, or the first changeover valve 52 is ON-operated simultaneously with or slightly after a completion of the punch-out. Consequently, the high oil pressure from the hydraulic source 31 runs into the lower chamber 48 via the hydraulic circuit 50, whereby the lowered pressure receiving member 45 is raised, and the slide lifter 11 reverts to the previous state. Then, the first changeover valve 52 is OFF-operated, resulting in a return to a state enough to perform the next working operation.
In accordance with the embodiment, the slide unit 12 is provided with the guide member 20 assuming the cross in plane. The surfaces 21 - 28 of the guide member 20 configure the perpendicular surfaces D, E, F, G facing in the tow orthogonal horizontal directions, i.e., in the to-and-fro directions and in the right-and-left directions. These perpendicular surfaces can be also, however, configured by forming the slide members in quadrangles. The present invention includes the slide members assuming such configurations,
Further, in accordance with the embodiment, the slide unit 12 has three pieces of slid members 12A, 12B, 12C. The number of the slide members is not, however, limited to this. In the embedment also, the two eccentric members 9A, 9C among the eccentric members 9A, 9B, 9C of the crank shaft 8 assume the same angular phase. However, the angular phases of all the eccentric members may be made different.
Additionally, in accordance with the embodiment, the con'rod 10 is connected through the wrist pin 49 to the slide lifter 11. This connection may be, however, effected by a connecting member having a spherical contact ball part.
Still further, the pressing machine may be provided with any one of the slide horizontal position adjusting device 42 and the slide lifter 11. Besides, a single member of the slide unit 12 may suffice for the pressing machine.
FIG. 7 illustrates a case where the pressing machine having the single member of the slide unit 12 is equipped with the slide horizontal position adjusting device 42 but with no slide lifter 11.
As described above, even when providing any one of the slide horizontal position adjusting device 42 and the slide lifter 11, the pressing machine performs the function of one of these devices. The performance of the pressing machine can be more enhanced than in the prior art.
Note that each embodiment can exhibits the function as the slide horizontal position adjusting device without adding any modification.
Although the illustrative embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments. Various changes or modifications may be effected by one skilled in the art without departing from the scope or spirit of the invention.

Claims

1. A pressing machine for working a material by a top tool secured to a slide unit connected via a con'rod to a crank shaft and by a bottom tool secured to a bolster,
characterized by comprising:

a slide unit (12) connected via a con'rod (10) to an eccentric unit (9) of a crank shaft (8);

slide horizontal position adjusting devices (42), so mounted on a frame of said pressing machine as to confront respective slide members of said slide unit (12) in the horizontal direction, for adjusting positions of said respective members of said slide unit (12); and

a slide lifter (11), provided between said slide unit (12) and said con'rod (10), for making said slide unit (12) ascendable and descendable with respect to said con'rod.

2. The pressing machine as set forth in claim 1, wherein said crank shaft (8) includes a plurality of members of said eccentric unit (9) which are disposed with an angular phase difference, and said members of said slide unit (12) which are independently separated from each other are connected to via said con'rods to said respective members of said eccentric unit (9).

3. The pressing machine as set forth in any of claim 1 or 2, wherein said slide unit (12) includes a guide member (20) encased in a box-like case (18) and standing erect; said guide member (20) assuming a cross in plane includes a forward extending portion (20A), a backward extending portion (20B), a leftward extending portion (20C) and a rightward extending portion (20D) which extend in the to-and-fro directions and in the right-and-left directions; and said extending portions (20A, 20B, 20C, 20D) have four perpendicular surfaces facing in two orthogonal horizontal directions, i.e., in the to-and-fro directions and in the right-and-left directions.

4. The pressing machine as set forth in any of claims 1 through 3, wherein said slide horizontal position adjusting device (42) is constructed of: position detecting sensors (40, 41) for detecting positions of said members of said slide unit (12) in the two orthogonal horizontal directions; a plurality of pads (30) attached to said frame of said pressing machine with slight gaps form said four perpendicular surfaces of said members of said slide unit (12) which face in the two orthogonal horizontal directions, said pads causing pressures of supplied pressure oils to act on said perpendicular surfaces; and control valves (33, 34, 35, 36), provided in a hydraulic circuit for supplying the pressure oil to said pads (30), for setting said slide unit in a proper horizontal position by regulating the supply of the pressure oils to said respective pads (30) in accordance with the slide horizontal position detected by said position detecting sensors (40, 41).

5. The pressing machine as set forth in any of claims 1 through 4, wherein said pads (30) are supplied with the high pressure oils from a hydraulic source (31) via a hydraulic circuit (32), and the pressures of the pressure oils supplied act on said respective surfaces of said slide unit (12) at upper and lower two stages.

6. The pressing machine as set forth in any of claims 1 through 5, wherein said slide lifter (1) is constructed of: a hydraulic cylinder (44) fixed to an upper end of said slide unit (12); a pressure receiving member (45) including a piston portion (46) for sectioning an internal chamber of said hydraulic cylinder (44) into an upper and lower chambers, said pressure receiving member having its upper part, fixed to the upper surface of said piston portion (46) and protruded from said hydraulic cylinder (44), to which a lower part of said con'rod (10) is connected; and changeover valves (52, 57), provided in a connection circuit for connecting said upper and lower chambers of said cylinder (44), for flowing the pressure oil of said lower chamber into said upper chamber.

7. A pressing machine for working a material by a top tool secured to a slide unit connected via a con'rod to a crank shaft and by a bottom tool secured to a bolster,

characterized by comprising:

position detecting sensors (40, 41) for detecting a position of a slide unit (12) in two orthogonal horizontal directions;

a plurality of pads (30) attached to a frame of said pressing machine with slight gaps form four perpendicular surfaces of said slide unit (12) which face in the two orthogonal horizontal directions, said pads causing pressures of supplied pressure oils to act on said perpendicular surfaces; and

control valves (33, 34, 35, 36), provided in a hydraulic circuit for supplying the pressure oil to said pads (30), for setting said slide unit in a proper horizontal position by regulating the supply of the pressure oils to said respective pads (30) in accordance with the slide horizontal position detected by said position detecting sensors (40, 41).

8. A pressing machine for working a material by a top tool secured to a slide unit connected via a con'rod to a crank shaft and by a bottom tool secured to a bolster,

characterized by comprising:

a hydraulic cylinder (44) fixed to an upper end of a slide unit (12);

a pressure receiving member (45) including a piston portion (46) for sectioning an internal chamber of said hydraulic cylinder (44) into an upper and lower chambers, said pressure receiving member having its upper part, fixed to the upper surface of said piston portion (46) and protruded from said hydraulic cylinder (44), to which a lower part of a con'rod (10) is connected; and

changeover valves (52, 57), provided in a connection circuit for connecting said upper and lower chambers of said cylinder (44), for flowing the pressure oil of said lower chamber into said upper chamber.

9. In a pressing machine for working a material by a top tool secured to a slide unit connected via a con'rod to a crank shaft and by a bottom tool secured to a bolster,

a slide horizontal position adjusting device comprising: