JPH07132400A - Press - Google Patents

Abstract

PURPOSE:To prevent the vibration of a press by providing a frame in a reciprocating manner in the vertical direction, and connecting a balancing weight to the frame through a link mechanism to prevent the balancing weight from horizontally reciprocating. CONSTITUTION:In a press 10, a link 38a is connected to an upper frame 14, and a link 38b is connected to a slide 20 respectively. The unbalanced force attributed to the vertical motion of the slide 20 is balanced by a balancing device 84. The balancing device 84 is located above the link mechanisms 36, 38 and a crankshaft 16, and provided with a balancing weight 86 which is movably supported in the vertical direction by the upper frame 14 and a weight guide 88 which limits the reciprocating motion of the balancing weight 86 in the vertical direction. A pair of connecting links 90 corresponding to the link mechanism 38 are provided. When the links 38a, 38b are bent, the bending angle of the links 38a, 90 is changed, and the balancing weight 86 is moved in the vertical direction. The unbalanced force attributed to the vertical motion of the slide 20 is cancelled by the balancing weight 86.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press machine for converting rotational movement of a crankshaft supported by a frame into reciprocating movement by a link mechanism or the like and transmitting the reciprocating movement to a slide.

[0002]

2. Description of the Related Art In a press such as a link press which converts a rotary motion of a crankshaft into a vertical motion by a link mechanism such as a knuckle mechanism and a toggle mechanism and transmits the vertical motion to a slide, a high speed operation is required. , It is important to balance the unbalanced force caused by the vertical movement of the slide.
For this reason, this type of press is equipped with a balancing device for balancing the unbalanced force.

As one of such press machines, a power transmission device having a pair of power transmission mechanisms for converting the rotational movement of the crankshaft into vertical movement and transmitting it to the slide, and the power transmission mechanisms are individually corresponded to. And a balancing device having a pair of balancing weights arranged on the side of the corresponding power transmission mechanism, wherein each balancing weight is vertically moved by 180 degrees in phase shift with respect to the vertical movement of the slide by the corresponding power transmission mechanism. (For example, Japanese Patent Publication No. 64-75200).

In this conventional press machine, each power transmission mechanism is provided with a link rotatably supported by the frame in the longitudinal center portion. Each link is pivotally connected or pivotally connected to the slide at one end and pivotally connected to a counterweight at the other end.

[0005] Each link is angularly reciprocally rotated about the pivotal support to the frame with the rotation of the crankshaft, that is, gives a swinging motion about the pivotal support. By doing so, the slide and the balance weight are reciprocally moved with the phase shifted by 180 degrees.

However, in the conventional press machine, since the slide and the balance weight are reciprocally moved by a common link,
The reciprocating movement of the balance weight becomes an arcuate oscillating movement about the pivotal support portion, and as a result, the balance weight reciprocates not only in the vertical direction but also in the horizontal direction.

Thus, when the balance weight is reciprocated not only in the vertical direction but also in the horizontal direction, even if the vibration of the press machine in the vertical direction is balanced, the vibration of the press machine in the horizontal direction is renewed. As a result, the press cannot be operated at high speed. Due to the structure of the conventional press machine, the movement of the balance weight in the horizontal direction cannot be restricted.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the press machine from vibrating in the horizontal direction as the balance weight reciprocates.

[0009]

A press machine according to the present invention comprises a power transmission device for transmitting a rotational movement of a crankshaft supported by a frame to a slide, and a balancing device for balancing an unbalanced force caused by the movement of the slide. Including and

The power transmission device is pivotally connected to the frame at a central portion in the longitudinal direction and is connected to the crankshaft by a connecting means so as to swing about a pivot point to the frame as the crankshaft rotates. A first link connected to the slide and having one end side connected to the slide.

The balancing device includes a balancing weight above the first link and the crankshaft and supported by the frame so as to be vertically reciprocable, and a lower end portion of the balancing weight of the first link. A connecting link that is pivotally connected to the other end and that is connected to the balance weight on the upper end side.

When the crankshaft is rotated, the first link is swung by the connecting means. As a result, the balance weight connected to the first link via the connecting link reciprocates in the vertical direction, and the slide indirectly connected to the connecting link reciprocates in the vertical direction.

The vertical movement of the balance weight and the slide is
The vertical movement of one end of the link (the part on the side connected to the balance weight) and the other end (the part on the side connected to the slide) is 1
Since the phases are shifted by 80 degrees, they are opposite to each other. As a result, the unbalanced forces caused by the vertical movement of the slide and the balance weight are canceled out.

As described above, according to the present invention, the balance weight is supported above the first link and the crankshaft so as to be reciprocally movable in the vertical direction, and the first link is pivotally attached to the frame. , The slide is connected to the one end side of the first link, and the balance weight is connected to the other end side of the first link via the connecting link, so that the balance weight reciprocates in the horizontal direction. It is possible to prevent the vibration of the press machine in the horizontal direction due to the reciprocating movement of the balance weight.

In the power transmission device, the upper end side is pivotally connected to the first link and the lower end side is connected to the slide so as to connect the first link to the slide. Preferably, the secondary link is provided. As a result, as the crankshaft rotates, the first and second links perform bending and stretching movements, whereby the slide and the balance weight are reciprocally moved in the vertical direction, so that the slide and the balance weight are stably reciprocated. .

The connecting means includes a connecting piece which is reciprocally moved by the rotation of the crankshaft, and a slider which is arranged on the frame so as to be vertically reciprocable and pivotally connected to the connecting piece. A third link is preferably provided, which is pivotally connected to the connecting piece or the slider on one end side and is connected to the first link on the other end side.

According to this structure, the connecting point between the third link and the connecting piece or the slider acts as a movable side fulcrum of the connecting means, and the slider cooperates with the frame to connect the third link and the connecting piece or. The moving direction of the connection point with the slider is restricted to the vertical direction. For this reason, when the crankshaft is rotated, the first and third links are oscillated in correct synchronization in accordance with the reciprocating movement of the coupling piece, so that the slide and the balance weight move in a more reliable synchronous vertical movement. do.

It is preferable that the balancing device further comprises at least one weight guide for vertically controlling the reciprocating movement of the balancing weight. As a result, the reciprocating motion of the balance weight can be reliably restricted to the vertical motion.

It is preferable that the frame has a guide portion that regulates the reciprocating movement of the slider in the vertical direction. As a result, the reciprocating movement of the slider is also restricted in the vertical direction, so the vertical movement of the slide and the balance weight is more stable.

The power transmission device includes a pair of the first links which are oscillated in synchronization with each other about a pivot point to the frame, and the parallel device is a pair individually associated with the first links. It is preferable to provide a pair of the connecting links, wherein the lower end side is pivotally connected to the corresponding first link and the upper end side is connected to the parallel weight. As a result, the reciprocating motion of the balance weight can be reliably restricted to the vertical motion.

From the viewpoint of further stabilizing the vertical movement of the slide and the balance weight, it is preferable to provide the first, second and third links and the connecting links in pairs.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a press 10 includes a lower frame 12 on which a lower die is placed, and an upper frame 14 supported by the lower frame. The crankshaft 16 is rotatably supported on the upper frame 14 about an axis extending in the horizontal direction, and the flywheel 1 shown in FIG.
Receive 8 rotations. So-called slide 2 that supports the upper mold
0 is attached to the lower ends of a pair of rods 22 that penetrate the lower end of the upper frame 14 in a vertically movable manner.

Both rods 22 extend upward from both ends of the slide 20 in parallel, and the power transmission device 3 converts the rotational movement of the crankshaft 16 into a vertical reciprocating movement.
0 reciprocates up and down. As a result, the slide 20 is reciprocated in the vertical direction.

The power transmission device 30 is connected to the crankshaft 16 and a connecting piece 32, which is reciprocally movable in the vertical direction on the upper frame 14, and is pivotally connected to the connecting piece 32. A pair of sliders 34,
A pair of link mechanisms 36 that flex and extend following the reciprocating movement of the slider and in synchronization with each other, and a pair of link mechanisms that individually correspond to the link mechanisms 36 and flex and extend following the flexing movements of the corresponding link mechanisms 36. A link mechanism 38 and a pair of sliders 40 arranged on the upper frame 14 so as to be displaceable in the vertical direction and pivotally connected to both link mechanisms 36.
And a position adjusting mechanism 42 for adjusting the position of the slider 40 in the vertical direction.

As shown in FIGS. 2 to 7, the connecting piece 32 is
It is connected to the eccentric part of the crankshaft 16 and is reciprocally moved in the vertical direction as the crankshaft 16 rotates. The sliders 34, 40 are received by a guide portion 44 formed on the upper frame 14 so as to be vertically movable. Both sliders 34 reciprocate in the vertical direction following the reciprocal movement of the connecting piece 32. Both sliders 40 reciprocate in the vertical direction following the bending and stretching movements of both link mechanisms 36.

As shown in FIGS. 2, 3 and 5, each link mechanism 36 includes a pair of links 36a and 36b. The links 36a and 36b of each link mechanism 36 have a lower end portion of the link 36a and an upper end portion of the link 36b.
The shafts 46 are flexibly connected to each other.

One link 36a of both link mechanisms 36
Are pivotally connected to the connecting piece 32 and the slider 34 at the upper end by a common pivot 48. The other link 36b of both link mechanisms 36 has a common pivot 5
It is connected to the lower end by 0 so that it can pivot.

In the illustrated example, the pivots 48, 50 are provided so that their pivot points coincide with the axis 52 (see FIG. 2) extending in the vertical direction via the center of rotation of the crankshaft 16. However, the pivots 48, 50 need not be so arranged.

In the illustrated example, the link 3 of the link mechanism 36
6a is directly connected to the connecting piece 32 and the slider 34, but the link 36a of the link mechanism 36 may be connected to only one of the connecting piece 32 and the slider 34.

As shown in FIGS. 2, 4 and 5, each link mechanism 38 includes a pair of links 38a, 38b. The links 38a and 38b are connected to each other by a pivot 54 so that they can be bent at the lower end of the link 38a and the upper end of the link 38b. Each link 38a is rotatably connected to a bracket 56 attached to the upper frame 14 by a pivot 58 at its longitudinal center portion. Each link 38b is pivotally connected to the rod 22 by a pivot 60 at its lower end.

Each link mechanism 38 is pivotally connected to the corresponding link mechanism 36 by a pivot shaft 54, a connecting body 62 and a pivot shaft 64 so as to flex and extend following the flexion and extension of the corresponding link mechanism 36. In the illustrated example, the pivots 58, 6
Zeros are provided so that their pivot axes coincide with the axis extending in the vertical direction via the axis of the rod 22. However, the pivots 58, 60 need not be so arranged.

In the illustrated example, each link mechanism 38 is connected to the link 36a by the connecting body 62, but the connecting body 62 may be connected to the link 36b, or the connecting body 62 may be connected to both links 36a, 36b. The link mechanism 38 may be connected to the link mechanism 36 without using the connecting body 62.
May be directly connected to the link mechanism 36, or one of the links 38a and 38b may be directly or indirectly connected to the link mechanism 36. The link 38a may be connected to the rod 22 by other connecting means instead of the link 38b.

As shown in FIG. 2, FIG. 3, FIG. 6 and FIG.
b and a bifurcated bracket 70 pivotally connected to both sliders 40, a male screw 72 extending downward from the bracket, a worm wheel 74 screwed to the male screw, and a worm screw meshing with the worm wheel. 7
6 and 6. Instead of using the bracket 70, the male screw 72 may be pivotally connected to the links 36b and the sliders 40 by the pivot 50.

The male screw 72 is connected to the bracket 70 so as not to rotate about the axis 52. The worm wheel 74 is rotatably supported by the support portions 78 and 80 of the upper frame 14 about the axis 52 and is not movable in the vertical direction. The shaft portion of the worm screw 76 rotatably passes through the upper frame 14 and has a sprocket 82 at the end portion (see FIG. 7). Sprocket 82
Is rotated by a rotating mechanism (not shown) such as an electric motor.

When the sprocket 82 is rotated, the worm screw 76 is rotated, and the worm wheel 74 meshing with the worm screw 76 is rotated, and the worm wheel 74 is rotated.
The male screw 72 that is screwed with is moved upward or downward, and finally the slider 40 is moved upward or downward.

In the press machine 10, the slider 34 is
As the crankshaft 16 rotates, the connecting piece 32 is reciprocally moved in the vertical direction, so that the connecting piece 32 is reciprocated in the same direction. Also, the slider 40 does not move unless the worm wheel 74 is rotated. Therefore, the pivot 48 acts as a movable side fulcrum of the link mechanism 36, and the pivot 50 acts as a fixed side fulcrum of the link mechanism 36.

Further, since the link 38a is connected to the upper frame 56 by the bracket 56, while the link 38b is connected to the slide 20 by the rod 22 which is vertically movable, the pivot 58 is connected to the link mechanism 3.
8 acts as a fixed side fulcrum, whereas the pivot 60 acts as a movable side fulcrum of the link mechanism 38.

The unbalanced force caused by the vertical movement of the slide 20 is balanced by the balancing device 84. This balancing device 8
Reference numeral 4 denotes a balance weight 86 that is above the link mechanisms 36 and 38 and the crankshaft 16 and is supported by the upper frame 14 so as to be vertically movable, and a plurality of weights that limit the reciprocating motion of the balance weight 86 in the vertical direction. It includes a guide 88 and a pair of connecting links 90 individually corresponding to the link mechanism 38.

Each connecting link 90 is connected at the lower end by a horizontally extending pivot 92 to the upper end of the corresponding link 38a of the link mechanism 38, and at the upper end by a horizontally extending pivot 94 a balancing weight 86. Are linked to.

In the illustrated example, the reciprocating movement of the parallel weight 86 is caused by the four weight guides 88 as shown in FIG.
It is restricted in the vertical direction. However, the reciprocating movement of the parallel weight 86 may be limited by one or more weight guides.

Axis 46, 48, 50, 54, 58, 6
0, 64, 92 and 94 extend horizontally in parallel with the rotation axis of the crankshaft 16. Therefore, the pivotal movement of the members interconnected by each pivot or the members supported by each pivot is a movement about an axis extending in the horizontal direction.

The rotation of the flywheel 18 depends on the crankshaft 1
6, the connecting piece 32 and the slider 34 reciprocate as the crankshaft 16 rotates, so that the link mechanisms 36 flex and extend in synchronization. As a result, both link mechanisms 38 are bent in synchronization, and as a result, the slide 20 is reciprocated. Therefore, the link mechanism 3
8 acts as a knuckle mechanism or a toggle mechanism.

When the links 38a, 38b are bent, the bending angles of the links 38a, 90 change in proportion to the bending angles thereof, so that the balance weight 86 is connected to the links 38a, 38b.
It is moved up and down according to the bending of. The reciprocating movement of the balance weight 86 at this time is downward when the slider 40 is moved upward, is upward when the slider 40 is moved downward, and is limited to the vertical reciprocating movement by the weight guide 88. As a result, the unbalanced force caused by the vertical movement of the slide 20 is canceled by the balance weight 86.

The balance weight 86 is vertically reciprocated by the link 38a via the connecting link 90. Therefore, although the balance weight 86 is connected to the link 38a of the link mechanism 38 that moves the slide 20 up and down, the horizontal displacement of the balance weight 86 is reliably prevented, and the reciprocating motion of the balance weight 86 is prevented. Vibration of the press machine in the horizontal direction due to the is prevented.

The reciprocating motion of the slider 34 is controlled by the guide portion 44.
Is regulated in the vertical direction by. Therefore, the bending movements of the link mechanisms 36 and 38 are correctly synchronized with each other, thereby reliably preventing the slide 20 and the balance weight 86 from vibrating in the horizontal direction.

When the slider 40 is moved upward regardless of the rotation of the crankshaft 16, the bending angle of each link mechanism 36 becomes small, and the bending angle of each link mechanism 38 becomes large, so that the slide 20 moves downward. Moved to. On the other hand, when the slider 40 is moved downward,
Since the bending angle of each link mechanism 36 becomes large and the bending angle of each link mechanism 38 becomes small, the slide 20 is moved upward.

When the slider 40 is moved upward or downward, the position of the slider 34 in the vertical direction does not change, so the bending angle of the link mechanism 36 changes, but the bending / extending range does not move in parallel in the vertical direction. Therefore, the bottom dead center position and stroke length of the slide 20 can be adjusted by rotating the sprocket 82.

The bottom dead center position of the slide 20 is detected by an arbitrary detector, the detected value is compared with a predetermined reference value, and the sprocket 82 is rotated so that the detected value becomes the reference value. , May be adjusted. Slide 20
The stroke length of can be set by rotating the sprocket 82 in advance by a predetermined amount.

If the position adjusting mechanism 42 is used, since the moving amount of the slider 40 is minute with respect to the rotating amount of the worm screw 76, both the bottom dead center position and the stroke length are finely and accurately adjusted. can do. But,
Other position adjusting mechanism using a lever mechanism or the like may be used, or the position adjusting mechanism may not be used. If the position adjusting mechanism is not used, the link 36b and the slider 40 are unnecessary.

As described above, the four link mechanisms 36, 38
Is used, the reciprocating movement of the slide 20 and the balance weight 86 is stabilized. In particular, the two link mechanisms 36 are arranged symmetrically with respect to the axis 52, the link mechanisms 38 are arranged symmetrically with respect to the axis 52 on both sides thereof, and the balance weight 86 is arranged above the crankshaft 16 and the link mechanisms 36, 38.
If they are arranged symmetrically with respect to each other and the lower ends of the balance weights in the horizontal direction are connected to the link mechanism, the reciprocating movement of the slide 20 and the balance weight 86 is stabilized.

From the standpoint of further stabilizing the reciprocal movement of the slide 20 and the balance weight 86, in particular, one link 36
a, 36b, 38a, 38b, one set consisting of one connecting body 62 and one connecting link 90, the other link 36a, 36b, 38a, 38b, the other connecting body 62
And the other set consisting of the other connecting link 90 are arranged symmetrically with respect to the axis 52, and the balance weight 86 is attached to the axis 5
It is preferable to arrange symmetrically with respect to 2.

However, the present invention is not limited to the above embodiment. For example, only one set of linkages 36, 38 may be used, in which case the counterweight 86 is connected to the linkage 38 in the horizontal central lower side by a plurality of links pivotally supported by the frame 14. Further, in the case where only one set of the link mechanisms 36 and 38 is used and the case where only the two sets of link mechanisms 36 and 38 are used, the links 36b and 38b may not be used.

FIG. 9 shows the link 36b of the link mechanism 36.
An embodiment of the press machine 100 that does not use the position adjustment mechanism 42 will be described. The press machine 100 shown in FIG.
6a is directly connected to the corresponding link mechanism 38 by a pivot 54.

In the press 100, the slider 34
Cooperates with the upper frame 14 to regulate the moving direction of the connecting point of the link 36a, the connecting piece 48 and the slider 34 in the vertical direction. Therefore, when the crankshaft 16 is rotated, the link mechanism 38 is flexed and extended correctly in synchronization with the links 36a as the slider 34 and the connecting piece 48 reciprocate. Move up and down more reliably in synchronization.

Also in the case of the press machine 100, one link 3
One set consisting of 6a, 38a, 38b and one connecting link 90 and the other link 36a, 38a, 38b
And the other set consisting of the other connecting link 90 are arranged symmetrically with respect to the axis 52, and the balance weight 86 is attached to the axis 5
It is preferable to arrange symmetrically with respect to 2. But,
Also in the case of the press machine 100, one set of links 36a, 38
Only a and 38b may be used, and other connecting means may be used instead of the link 38b.

The embodiments of the present invention described with reference to the drawings can be summarized as described below.

Summary 1. The press machine according to claim 3, wherein the connecting means is further arranged in the frame so as to be displaceable in the vertical direction, with a fourth link pivotally connected to the third link at the upper end, and A second slider pivotally connected to the fourth link and a mechanism for adjusting the position of the second slider in the vertical direction are provided. When a pair of third links is provided, the connecting means includes a pair of the fourth links individually corresponding to the third links and connected to the corresponding third links, The second link is preferably connected to both the fourth links. In either case, when the second slider is vertically displaced with respect to the frame by the position adjusting mechanism, the position of the connection point between the fourth link and the second slider is vertically changed. At this time, since the positions of the third link and the slider or the connecting piece and the connecting point are not changed,
The bending angles of the third and fourth links change and the position of the second slider in the vertical direction changes, without the bending and extending ranges of the third and fourth links moving in parallel in the vertical direction. As a result, the bottom dead center position and stroke length of the slide can be adjusted.

Summary 2. The press machine according to claim 6 or 1, wherein the position adjusting mechanism is a male screw which is connected to the second slider and extends in the vertical direction, and a worm wheel which is screwed to the male screw and which is attached to the frame. The worm wheel is provided so as to be rotatable about an axis extending in the vertical direction and immovable in the vertical direction, and a worm screw that meshes with the worm wheel. By doing so, the worm wheel cannot be displaced in the vertical direction, so that when the worm wheel is rotated, the second wheel
The slider is vertically displaced, and the bottom dead center position and stroke length of the slide change. Therefore, both the bottom dead center position of the slide and the stroke length can be finely adjusted.

Summary 3. In the press machine described in the summary 1, the frame has a guide portion that restricts the movement of the second slider to reciprocate in the vertical direction. In this way, both the bottom dead center position of the slide and the stroke length can be adjusted more finely and more accurately.

[Brief description of drawings]

FIG. 1 is a partially sectional front view showing an embodiment of a pressing machine of the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion of a power transmission device and a balancing device of the press machine of FIG.

3 is an enlarged sectional view taken along line 3-3 in FIG.

FIG. 4 is an enlarged sectional view taken along line 4-4 in FIG.

5 is an enlarged sectional view taken along line 5-5 in FIG.

FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG.

FIG. 7 is an enlarged sectional view taken along line 7-7 in FIG.

FIG. 8 is an enlarged cross-sectional view taken along line 8-8 in FIG.

FIG. 9 is a partially sectional front view showing another embodiment of the pressing machine of the present invention.

[Explanation of symbols]

 10, 90 Press machine 12, 14 Frame 16 Crankshaft 18 Flywheel 20 Slide 22 Rod 30 Power transmission device 32 Connecting piece 34 Slider 36 Link mechanism 36a link (3rd link) 36b Link (4th link) 38 Link mechanism 38a link (first link) 38b link (second link) 40 second slider 42 position adjusting mechanism 44 guide part 62 connecting body 70 bracket 72 male screw 74 worm wheel 76 worm screw 78, 80 support part 82 sprocket 84 balance Device 86 Balance weight 88 Weight guide 90 Connection link

[Procedure amendment]

[Submission date] February 2, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

If the position adjusting mechanism 42 is used, since the moving amount of the slider 40 is minute with respect to the rotating amount of the worm screw 76, both the bottom dead center position and the stroke length are finely and accurately adjusted. can do. But,
Other position adjusting mechanism using a lever mechanism or the like may be used, or the position adjusting mechanism may not be used. When the position adjusting mechanism is not used, the structure shown in FIG. 9 can be used.

Claims (8)

[Claims] 1. A press machine comprising: a power transmission device for transmitting a rotational movement of a crankshaft supported by a frame to a slide; and a balancing device for balancing an unbalanced force caused by the movement of the slide. A first device is pivotally connected to the frame at a central portion in the longitudinal direction and is connected to the crank shaft by a connecting means so as to swing about a pivot point to the frame with rotation of the crank shaft. A first link whose one end side is connected to the slide, wherein the balancing device reciprocates vertically in the frame above the first link and the crankshaft. A balance weight supported so that the lower end side is pivotally connected to the other end of the first link, and the upper end side is connected to the balance weight. A press machine. 2. The power transmission device further comprises the first
7. A second link pivotally connected to the first link on the upper end side and to the slide on the lower end side to connect the second link to the slide. Press machine. 3. The connecting means includes a connecting piece that reciprocates as the crankshaft rotates, and a slider that is arranged on the frame so as to be vertically reciprocable and pivotally connected to the connecting piece. And a third link having one end side pivotally connected to the connecting piece or the slider and the other end side connected to the first link. Press machine. 4. The press machine according to claim 1, wherein the balancing device further includes at least one weight guide that vertically regulates the reciprocating movement of the balancing weight. 5. The frame includes a guide portion that vertically regulates reciprocal movement of the slider.
The press machine according to any one of 4 above. 6. The power transmission device comprises a pair of the first links that are oscillated synchronously about a pivot point to the frame, and the parallel devices are individually associated with the first links. 2. A pair of the connecting links, wherein the pair of connecting links are pivotally connected to a corresponding first link on a lower end side and are connected to the parallel weight on an upper end side. Press machine described in. 7. The power transmission device further comprises the first
A pair of second links individually corresponding to the above links and corresponding first links to the slide,
A pair of second ends pivotally connected to the corresponding first link on the upper end side and to the slide on the lower end side.
7. The press machine according to claim 6, further comprising: 8. The connecting means includes a connecting piece that reciprocates as the crankshaft rotates, and a slider that is arranged on the frame so as to be vertically reciprocable and pivotally connected to the connecting piece. And a pair of third links respectively corresponding to the first links, one end side being pivotally connected to the connecting piece or the slider and the other end side corresponding. The press machine according to claim 6 or 7, further comprising a pair of third links connected to the first links.