GB2315237A - Slide driving apparatus for mechanical press - Google Patents

Abstract

A mechanical press has a drive shaft to which power from a motor is transmitted through a transmission system including a flywheel 3 and a clutch. A pinion on the drive shaft drives a drive gear 5 fixed to a crankshaft 6 which provides a reference phase. The crankshaft 6 drives a reference slide 8. The drive gear 5 drives a driven gear 9, 11 provided on each of other crankshafts 10, 12 which drive different slides 15, 16 in the mechanical press. Each driven gear 9, 11 is disengageable from the drive gear 5. After disengagement, the rotational phase relation between a drive gear 9, 11 and the drive gear 5 can be changed and, thereafter, the drive gear 9, 11 be brought again into engagement with the drive gear 5. The sequence of the pressing steps to be performed by the different slides, as well as the phase differences, are thus determined and set so as to ensure that each step can be performed without being affected by the pressing operations which are being performed by other slides.

Description

SLIDE DRIVING APPARATUS FOR MECHANICAL PRESS BACKGROUND OF THE INVENTION The present invention broadly relates to a mechanical press for producing machine parts by press work and, more particularly, to an apparatus for driving slides incorporated in a mechanical press.

Mechanical presses have been known of the type which employs a plurality of slides for the purpose of producing machine parts through a plurality of steps of pressing work One of the mechanical presses of the type mentioned above incorporates slides which operate at different phases with fixed phase differences from one another, in order to reduce the cost of the press while eliminating any undesirable mutual interference or influence between different slides so as to ensure high degree of precision of the work.

The fixed phase relation between different slides, however, causes such an inconvenience in regard to phases that press work is being conducted by one of the slides when another slide is just going to commence the work or executing the work, when the type of the machine part to be press-formed is changed, resulting in the following undesirable effects: (a) A slide which is required to work at an extremely high precision is obliged to operate with inferior precision due to influence of distortion of the mechanical press which is caused by the pressing load applied during working of another slide.

(b) Simultaneous working of a plurality of slides increases the total pressing load applied to the mechanical press, with the result that the distortion of the mechanical press, as well as vibration and noise, is increased.

(c) The components of the press incorporated in the power system including the power source and the actuating mechanisms have to be designed and constructed so as to withstand the maximum pressing load which may be applied due to simultaneous working in two or more slides. This makes it difficult to provide inexpensive mechanical press.

No mechanical press has been proposed up to date which would overcome these problems.

SUMMARY OF THE INVENTION Object and Brief Summary of the Invention: Accordingly, an object of the present invention is to provide a small-sized mechanical press in which, when it is required to change the steps of the pressing process in accordance with the type of the mechanical part to be pressed, phase relation between the slides is adjusted in accordance with the change in the steps in such a tanner as to reduce the total pressing load which is the sum of the loads imposed on the slides which operate simultaneously, while maintaining high precision of the press work performed by individual slide.

In this regard the invention provides a slide driving apparatus as set out in Claim 1 ln a mechanical press in accordance with the present invention, power is derived from a motor and transmitted to a drive shaft through a transmission system which includes a flywheel and a clutch. Power is further transmitted to a crankshaft through a pinion provided on the drive shaft and a drive gear which is provided on the crankshaft. The crankshaft drives a reference slide which provides a reference for the phase of operation. The drive gear drives driven gears on other crankshafts so as to drive the slides associated with these crankshafts.

The arrangement is such that each driven gear can be disengaged from the drive gear and, after a change is effected in the phase relation between the drive and driven gears, brought again into engagement with the drive gear, whereby a sequence and phase differential of the press work to be performed by individual slides are determined and set such that the work of each slide can be executed without being affected by other slide or slides.

Consequently, a mechanical press can be obtained incorporating a slide driving mechanism which reduces the total press load as the sum of the press load on the slides working simultaneously, while achieving high precision of motion of the slides.

The above and other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiments when the same is read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional front elevational view of a major part of the apparatus in accordance with the present invention; Fig. 2 is a sectional side elevati-- l view of the major part of the apparatus in accordance with the present invention; Fig. 3 is an illustration of a mechanism used in the apparatus of the present invention for altering the phase relation between meshing gears; Fig. 4 is an illustration of a mechanism for manually changing the phase relation between meshing gears; and Fig. 5 is an illustration of positions of slides operative at phase differences which are set in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A mechanical press incorporates a plurality of slides each of which is driven through its own driving system incorporating a drive gear, a crankshaft and a connecting rod.

All these driving systems are actuated by an actuating system which includes a motor, a flywheel, a clutch, a drive shaft and a pinion fixed on the drive shaft. One of the slides, which is referred to as a "reference slide" hereinafter and which provides a reference for the phase relations of the slides in the press, is driven by the aforementioned pinion which engages with the drive shaft associated with this reference slide. The drive gear of the driving system for the reference slide, i.e., the drive gear foxed to the crankshaft associated with the reference slide or, alternatively, a separate drive gear fixed to this crankshaft engages with driven gears which are associated with other slides. It is therefore possible to change the phase of each of other slides with respect to the phase of the reference slide, by disengaging the driven gear associated with the slide from the above-mentioned drive gear and then bringing again the driven gear into engagement with the drive gear after changing the phase relation between the drive and driven gears. It is thus possible to change the sequence of operation of the steps to be performed with the slides, as well as phase differences between the operations to be performed by the slides.

An embodiment of the present invention will be described with reference to Figs. 1 to 4.

Power is transmitted from a motor 1 to a flywheel 3 through a belt 2. The power is further transmitted to a drive gear 5 via a pinion 4, through a clutch and a drive shaft which are not shown.

The drive gear 5 is fixed to a crankshaft 6 associated with one of the slides which is used as the reference slide. A connecting rod 7 has a big end which rotatably embraces an eccentric portion 6A of the crankshaft 6, while a small end of the connecting rod 7 is rockably secured to the above-mentioned reference slide which is denoted by 8.

A driven gear 9 engaging with the drive gear 5 is fixed to a crankshaft 10, while a driven gear 11 which engages with another drive gear 5 on the crankshaft 6 is fixed to a crankshaft 12.

The crankshaft 10 has an eccentric portion 10A which is rotatably supported by a big end of a connecting rod 13, while a small end of the connecting rod 13 is rockably connected to a slide 15.

Similarly, the crankshaft 12 has an eccentric portion 12A which rotatably carries a big end of a connecting rod 14, while a small end of the connecting rod 14 is rockably attached to a slide 16.

Fig. 3 illustrates an example of an automatic adjusting means which changes the phase of the slide 15 with respect to the reference phase, i.e., the phase of the slide 8, through changing the rotational phase relation between the drive and driven gears which mesh with each other.

The driven shaft 9 is fixed to the crankshaft in such a manner as not to be rotatable relative to the crankshaft 10 but is allowed to move in the axial direction of the crankshaft 10. Thus, the driven gear 9 is, for example, splined to the crankshaft 10. A pressurized fluid is supplied from a rotary joint 21 so as to urge a piston 20 against a biasing force exerted by a spring 22. As a result, a cup 23 fixed to the piston 20 and the driven gear 9 which is fixed to the cup 23 are moved together to the right as viewed in Fig. 3, whereby the driven gear 9 is disengaged from the drive gear 5.

After the drive gear 5 or the driven gear 9 has been rotated by an amount in terms of the number of teeth corresponding to the amount of change of the phase difference to be effected, the above-mentioned pressurized fluid is relieved, so that the driven gear 9, together with the cup 23 and the piston 20, is moved to the left as viewed in Fig. 3 by the force of the spring 22, so as to be brought again into engagement with the drive gear 5.

Thereafter, the axial position of the driven gear 9 is maintained constant with respect to the crankshaft 10, by the force of he spring 22.

The driven gear 11 is arranged in the same manner as the driven gear 9 described above, so that the phase of this gear 11 with respect to the drive gear 5 meshing with the driven gear 11 can be adjusted to achieve the required phase difference.

As a result of the changes in the rotational phases of the driven gears 9 and 11 with respect to the drive gears 5, 5, the phases of operations of the slides 15, 16 driven by the crankshafts 10, 12 through the connecting rods 13, 15 are changed with respect to the phase of operation of the reference slide.

Fig. 4 shows an example of a manual system which performs, as in the case of the arrangement shown in Fig.

3, a change of the phase of the slide 15 with respect to the reference slide 8.

In contrast to the arrangement shown in Fig. 3 which employs a pressurized fluid and a spring as the means for axially shifting and retaining the driven gear 9, the manual system shown in Fig. 4 employs bolts 31, 32 which by means of which the change in the phase difference can be achieved in the same way as that in the example shown in Fig. 3, although in this case the force for bringing the driven gear out of and into engagement with the drive gear is exerted manually.

Fig. 5 is a diagram illustrating an example of the operation phases of the slides. The axial of abscissa indicates the rotational angle of the crankshaft 6 which drives the reference slide 8, while axis of ordinate indicates the positions of the respective slides in their strokes. Thus, the value 0 (zero) along the axis of ordinate indicates that the slide is at the bottom dead center of its stroke. The phase of the slide 15 is 300 ahead of the phase of the reference slide 8 in terms of the crank angle. The phase of the slide 16 delays 300 after the phase of the reference slide 8 in terms of the crank angle. Assuming here that the slides have a stroke length of 400 mm, it will be understood that no overlap of the press operations performed by the slides takes place in the range down to 30 mm in terms of the pressing work height or stroke when the phase differences are 300 as described above. The diagram shown in Fig. 5 provide data concerning whether or not any overlap occurs, as well as the amount of overlap, even when the slides have different heights of the pressing work or strokes, thus serving as a diagram which is to be referred to by the user when the user wishes to effect a change in the phase difference between different slides.

According to the present invention, it is thus possible to suitably change the phase relations among different slides in the mechanical press. Consequently, it is not necessary any more for a mechanical press to have a capacity which is large enough to accommodate the sum of the maximum allowable loads to be imposed on the individual slides incorporated in the mechanical press.

Thus, the amount of distortion of the mechanical press which is caused during the operation can be reduced even when the whole mechanical press is comparatively small in size. In addition, when an extremely high degree of precision is required for a specific slide, the phase relations can be set such that the pressing work by such a slide can be performed without being affected by the operations of other slides. It is thus possible to eliminate the problem in regard to inferior precision which has been experienced in conventional mechanical press due to mutual influence of different steps performed by different slides in the mechanical press. Furthermore, since the differences in phase among different slides can be set suitably, it is possible to reduce the total pressing load acting on the whole mechanical press in terms of the sum of the loads acting on all the slides which are operating simultaneously. For the same reasons, distortion of the frame and other parts of the mechanical press can be diminished, with the results that vibration and noise are reduced during the operation of the mechanical press.

Although the invention has been described through its preferred form, it is to be understood that the described embodiments are only illustrative and various changes and modifications may be imparted thereto without charting from the scope of the present invention which is limited solely by the appended claim.

Claims (1)

1. WHAT IS CLAIMED IS:

   1. A slide driving apparatus for use in a multi-step mechanical press of the type having a plurality of slides which are driven through crankshafts and connecting rods by a common power source through gears, said slide driving apparatus comprising: a driving system for driving each of said slides, including said gear, said crankshaft and said connecting rod, said plurality of slides including a reference slide which provides a reference in regard to the phase relations of said slides, the drive gear fixed to the crankshaft of the driving system for driving said reference slide driving driven gears which serve as said drive gears of the driving systems for other slides; and phase difference changing means for disengaging each said driven gear from said drive gear on said crankshaft of said driving system for driving said reference slide and for bringing said driven gear again into engagement with said drive gear after a change in the rotational phase relation between said driven gear and said drive gear, so that the phases of the crankshafts of said slides can be changed to cause changes in the phases of operations of said slides with respect to said reference slide, thus renewing the sequence and the timings of the steps of the press work performed by said slides.

   2 A slide driving apparatus substantially as hereinbefore described with reference to figures 1 2, 5 and 3; or figures 1, 2, 5 and 4 of the accompanying drawings