Slide device in mechanical press

A screw mechanism is used to change the shut height of a mechanical press. A clearance between thread faces of a female screw and a male screw in this screw mechanism is shifted to one of the thread faces, on which an operating load of the press acts, by pressing the other thread face, which receives the operating load, by the action of a hydraulic force from a hydraulic cylinder mechanism, by which the clearance is always positioned on the side of one thread face. Since the female and male screws cannot rotate relatively and put in a lock state while the thread faces are pressed to one side, the position of a slide does not change even if the press is driven in this state. A hydraulic cylinder for quick die opening is provided separate from a hydraulic cylinder for locking the female and male screws in the shut height adjustment, by which the slide is moved upward or downward. This achieves a quick die opening mechanism used for maintenance and checks of the press which maintains a sufficient and constant upward stroke length of the slide even though the shut height changes.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a mechanical press, and more particularly, 
to improvements in a slide adjustment mechanism for adjusting the shut 
height and a quick die opening mechanism used for maintenance and checks 
of a die held attached to a mechanical press. 
2. Description of the Related Art 
The slide adjustment to change the shut height is normally made by changing 
the length of engagement of a female screw and a male screw, and 
therefore, a clearance needs to be formed in an engaging portion between 
the female and male screws. 
However, since a slide freely moves in the vertical direction by an amount 
corresponding to the clearance between the screws, the position of the 
slide changes. This positional change of the slide lowers the accuracy of 
stamped parts, and further hastens the deterioration of a die. 
Another type of mechanical press, in which the stroke length of a slide is 
short, is difficult to be subjected to maintenance and checks in a state 
where a die is held attached thereto even though the slide is raised to 
the top dead center. 
In order to solve these problems, the prior art shown in FIG. 5 has the 
following structure. A piston rod 7 is coupled to a connecting rod, which 
is not shown, at the top thereof and slidably fitted in a male screw 
member 17 at the bottom thereof. A rotatable female screw member 9 is 
mounted on a slide 16 such that it cannot move vertically, and a piston 
portion 7A of the piston rod 7 is located in a hydraulic cylinder 31 
mounted on the slide 16, thereby constituting a hydraulic cylinder device. 
In the above-mentioned structure, an upward-acting hydraulic force is 
exerted on the piston rod 7 by supplying pressure oil into a hydraulic 
chamber 32 to lift up the male screw member 17. A clearance between thread 
faces of a male screw of the male screw member 17 and a female screw of 
the female screw member 9 is thereby shifted to one side and the screws 
are locked, so that the clearance between the thread faces has no 
influence on stamping. A stamping operation is carried out in this state. 
Maintenance and checks of a die or adjustment of the shut height is 
performed in a state in which the slide is put in the upper position by 
discharging the pressure oil from the hydraulic chamber 32. 
The above mechanism doubles as a slide adjustment mechanism for changing 
the shut height and a quick die opening mechanism for moving a slide 
vertically, and further serves to lock screws in the slide adjustment. 
However, in the slide adjustment mechanism of the prior art, there is a 
clearance on the thread face side which receives an operating load acting 
on the slide 16, and the operating load is supplied from the hydraulic 
force of the hydraulic chamber 32. If the operating load acts in this 
state, the oil in the hydraulic chamber 32 is compressed under pressure, 
by which the volume thereof decreases. This decrease in volume changes the 
position of the slide 16. 
Furthermore, since the slide adjustment for changing the shut height is 
made by changing the vertical positions of the male screw member 17 and 
the female screw member 9, that is, the length of engagement thereof, the 
male screw member 17 functioning as a stopper for the piston rod 7 is 
moved vertically relative to the slide 16 by the slide adjustment, and 
thereby, a stroke length L1 for quick die opening changes. 
Still furthermore, since the shut height can be adjusted only in a quick 
die opening state, workability is poor. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to solve the 
above-mentioned problems of the prior art. 
In order to achieve the above object, a slide device in a mechanical press 
according to the present invention has the following features: 
(a) The shut height is controlled by a slide adjustment mechanism using a 
screw mechanism in a similar manner to the prior art. A hydraulic force is 
exerted on one of thread faces of a female screw and a male screw in the 
screw mechanism, which receives an operating load of the press, by a 
hydraulic cylinder mechanism, so that the clearance between the female and 
male screws is shifted to the side of the other thread face on which the 
operating load acts. The clearance between the female and male screws is 
thereby always shifted on the side of one thread face. Furthermore, since 
the slide adjustment mechanism fixes the female and male screws against 
relative rotation and puts the screws in a lock state while one thread 
face is being pressed against the other thread face, it is possible to 
drive the press without changing the position of a slide. 
(b) A hydraulic cylinder for quick die opening is provided, separate from a 
hydraulic cylinder for locking the female and male screws for slide 
adjustment, to move the slide upward or downward. This achieves a quick 
die opening mechanism used for maintenance and checks of the press which 
is not affected by the slide adjustment and maintains a sufficient and 
constant upward stroke length of the slide. 
More specifically, according to the present invention, there is provided a 
slide device in a mechanical press which vertically moves a slide through 
a connecting rod by rotating a crank shaft and has a slide adjustment 
device, the slide adjustment device comprising a hydraulic cylinder device 
acting between the connecting rod and the slide and having a hydraulic 
cylinder body; a slide adjustment mechanism including a male screw located 
on the outer periphery at the bottom of the hydraulic cylinder body and a 
female screw member with a female screw in meshing engagement with the 
male screw, the female screw member being fixed against vertical movement 
and rotatable relative to the slide; a cylindrical member fitted on the 
outer periphery of the hydraulic cylinder body and coupled to the slide; a 
hydraulic chamber formed by the hydraulic cylinder body and the 
cylindrical member; and a pressure oil supply means for supplying or 
discharging pressure oil to or from the hydraulic chamber, and for 
pressing the male screw against the female screw in the axial direction 
and locking the male and female screws by supplying the pressure oil to 
the hydraulic chamber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A slide device in a mechanical press according to the present invention has 
the following structure. 
A hydraulic cylinder is provided between a connecting rod and a slide. A 
piston rod as a component of the hydraulic cylinder is coupled to the 
connecting rod through a coupling member at the top thereof, and guided 
movably in the vertical direction by both a cylinder head and a 
cylindrical hole respectively formed at the top and bottom of a hydraulic 
cylinder body. 
A male screw is formed around the bottom end of the hydraulic cylinder 
body, and constitutes a slide adjustment mechanism in combination with a 
rotatable female screw member mounted on the slide and fixed against 
vertical movement. 
A cylindrical member fixed to the slide is fitted on the hydraulic cylinder 
body to form a hydraulic chamber therebetween. A clearance in an engaging 
portion between male and female screws is shifted to one side and the 
screws are locked by acting pressure oil on the hydraulic chamber. 
An embodiment of the present invention will be described below with 
reference to FIGS. 1, 2, 3 and 4. 
A slide 16 is guided by an upper guide device 19 and a post guide 20 such 
that it can move not horizontally, but vertically. A connecting rod 3 is 
coupled to a crank shaft 2, and to a coupling member 4 through a wrist pin 
6 at the bottom thereof. The coupling member 4 is vertically guided by a 
guide member 5 mounted on a crown 1. The guide member 5 and the coupling 
member 4 constitute the aforesaid upper guide member 19. The coupling 
member 4 is connected to the top of an upward-pointing piston rod 7 in a 
hydraulic cylinder device 32 by a bolt 4A. The piston rod 7 is guided 
movably in the vertical direction by a cylinder head 18 and a cylindrical 
hole 8A formed at the bottom of a hydraulic cylinder body 8, thereby 
constituting the hydraulic cylinder device 32. First and second hydraulic 
chambers 13 and 14 are respectively formed on and under a piston portion 
7A of the piston rod 7. A cylindrical member 12 is fitted on the outer 
periphery of the hydraulic cylinder body 8, between which a third 
hydraulic chamber 15 is formed, and joined to the slide 16 by bolts 12A. 
A male screw portion 8B formed at the bottom of the hydraulic cylinder body 
8 is screwed in a female screw 9A of a female screw member 9, thereby 
constituting a slide adjustment mechanism for changing the position of the 
slide. 16. The female screw member 9 is rotatably fitted in the slide 16 
and the vertical movement thereof is limited by a presser plate 11. 
A quick die opening mechanism is operated as follows by a hydraulic circuit 
which supplies and discharges pressure oil for driving the hydraulic 
cylinder device 32. 
(a) When a quick die opening diverter valve 25 is switched to a side 25A, 
pressure oil in the first hydraulic chamber 13 is discharged, pressure oil 
is supplied to the second hydraulic chamber 14, and the piston rod 7 is 
urged upward by the hydraulic force and moved to the uppermost position, 
which moves the slide 16 downward and allows a stamping operation. 
(b) When the quick die opening diverter valve 25 is switched to a side 25C 
to the contrary, pressure oil is supplied to the first hydraulic chamber 
13 and pressure oil in the second hydraulic chamber 14 is discharged. The 
piston rod 7 moves to the lowermost position, and the slide 16 moves 
upward, thereby bringing about a quick die opening state. 
The shut height is controlled in the following manner. 
(c) After a slide lock diverter valve 26 is switched to a side 26A and 
pressure oil in the third hydraulic chamber 15 is discharged, the female 
screw member 9 is rotated to move the hydraulic cylinder body 8 only by 
the required amount in the upward or downward direction. 
(d) After the change of the shut height is completed, the diverter valve 26 
is switched to a side 26B, a clearance T in a screw engaging portion 
between the female screw member 9 and the male screw 8A is shifted to one 
side and locked by a hydraulic force as shown in FIG. 3. 
Although a single hydraulic cylinder doubles as a quick die opening 
mechanism and a lock mechanism for slide adjustment in the prior art, 
hydraulic cylinders are provided for the respective mechanisms in the 
present invention as mentioned above. Therefore, since the quick die 
opening stroke length does not change even if the shut height is changed, 
maintenance and checks are easily performed. Furthermore, an easy slide 
adjustment is allowed even when the slide is down or in the quick die 
opening state.