CA2205531C - Power transmission for mechanical press - Google Patents

Power transmission for mechanical press Download PDF

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Publication number
CA2205531C
CA2205531C CA002205531A CA2205531A CA2205531C CA 2205531 C CA2205531 C CA 2205531C CA 002205531 A CA002205531 A CA 002205531A CA 2205531 A CA2205531 A CA 2205531A CA 2205531 C CA2205531 C CA 2205531C
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CA
Canada
Prior art keywords
gear
shaft
servo motor
power
planetary
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
CA002205531A
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French (fr)
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CA2205531A1 (en
Inventor
Keiichiro Hayashi
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IHI Corp
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IHI Corp
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Publication date
Priority to JP4-89259 priority Critical
Priority to JP8925992 priority
Priority to JP30794692 priority
Priority to JP4-307946 priority
Priority to JP4-317962 priority
Priority to JP31796292 priority
Priority to JP4-358010 priority
Priority to JP35801092A priority patent/JP3484714B2/en
Priority to JP5-32395 priority
Priority to JP03239593A priority patent/JP3326844B2/en
Priority to CA 2091747 priority patent/CA2091747C/en
Application filed by IHI Corp filed Critical IHI Corp
Publication of CA2205531A1 publication Critical patent/CA2205531A1/en
Application granted granted Critical
Publication of CA2205531C publication Critical patent/CA2205531C/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B30PRESSES
    • B30BPRESSES IN GENERAL
    • B30B1/00Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen
    • B30B1/26Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen by cams, eccentrics, or cranks
    • B30B1/266Drive systems for the cam, eccentric or crank axis

Abstract

A power transmission shaft which transmits rotational energy of a flywheel is divided into a first shaft section adjacent to the flywheel and a second shaft section adjacent to a power take-off gear. A planetary gearing is arranged between the shaft sections and is adapted to be driven by a servo motor. A power take-off gear is mounted on an output section of the planetary gearing so as to transmit the power to drives. The servo motor controls the rotation of the output section of the planetary gearing to vary the rotation of the power take-off gear so that the action velocity of the slide or the like can be freely controlled and press working for different kinds of materials can be carried out. A load cell on the slide drive for detecting any overload acting on the slide are for providing a sequel to the servo motor.

Description

CA 0220~3l l997-0~-2l BACKGROUND OF THE INVENTION
The present invention relates to a power transmission for a mechanical press for transmitting driving force of a main motor to a slide drive, a workpiece conveyance drive or the like.

BRIEF DESCRIPTION OF THE DRA~INGS
Figure 1 is a schematic view showing a conventional power transmission for a mechanical press;
Figures 2 to 13 are schematic views showing first to twelfth embodiments of a power transmission for a mechanical press lo according to the present invention, respectively;
Figure 14 is a schematic view showing flows of electric and mechanical powers in the tenth embodiment shown in Figure 11;
and Figures 15 and 16 are schematic views showing thirteenth and fourteenth embodiments of the present invention, respectively.
In some conventional mechanical presses, a die-supporting slide is driven by a slide drive to press a workpiece.
In time with the pressing operation, a workpiece conveyance drive is driven to convey a workpiece. Thus, workpi.eces are continuously formed into products.
Figure 1 shows an example of a power transmission for transmitting driving force to slide and workpiece conveyance drives. A main motor 1 is driven to rotate a flywheel 2 and store rotational energy in the flywheel 2. A clutch 3 is then engaged with the flywheel 2 to transmit the rotational energy stored in the flywheel 2, as driving force, to a power transmission shaft 4.
The driving force is taken by a power take-off gear 5 on the shaft CA 0220~3l l997-0~-2l 4 and is transmitted through a junction gear 6 to a pinion 7 coaxial with the gear 6. The pinion 7 is rotated to drive a slide drive 8 so that a slide 9 which supports a die is driven to carry out a pressing operation. At the same time, the rotation o~ the junction gear 6 is also transmitted through a bevel gearing 10 or the like to a work conveyance drive 12. Reference numeral 11 denotes a brake for the power transmission shaft 4.
In the above-mentioned conventional power transmission for structural reasons, movements of the drives 8 and 12 can be controlled only by selective engagement and disengagement of the clutch 3 and velocity-control of the flywheel 2. Therefore, for example, action velocity of the slide 9 cannot be controlled during a stroke of movement of the slide 9; pressing working cannot be carried out with the slide 9 being temporarily stopped at its bottom dead point of movement. As a result, pressing working for different kinds of materials is considerably limited.
In the conventional power transmission, the slide drive 8 is actuated by engaging the clutch 3 to the flywheel 2 which is rotating; this causes mechanical shock and a lot of noise.
Moreover, structurally, the clutch 3 requires connection pads such as friction inserts, which are consumables; thi~ requires a great number of pads to be prepared for exchange and periodic maintenance has to be carried out for checking whether the pads being used are to be exchanged or not.
In view of the above, a primary object of the present invention is to provide a power transmission ~or a mechanical press which can control action velocity of a slide or the like to CA 0220~31 1997-0~-21 -non-limitatively carry out press working for different kinds of materials and which employs no clutch, which is a cause of mechanical shock and requires consumables to be exchanged, to thereby carry out press working with no maintenance for consumahles and with low cost.
To attain the above ob ject, in a power transmission wherein rotational energy stored in a flywheel is taken through a power transmission shaft by a power take-off ~ear and is transmitted to a drive, the present invention resides in that the power transmission shaft is divided into firs~ and second shaft sections adjacent to the flywheel and the power take-off gear, respectively, a planetary gearing being arranged between the shaft sections and adapted to be driven by a servo motor, the power take-off being mounted on an output section of said planetary gearing.
In another aspect of the invention, a planetary gearing is arranged between the shaft sections and has at its portion a variable torque brake which is controlled by a control unit.
In a further aspect of the invention, a planetary ~0 gearing is arranged between the shaft sections and is driven by a servo motor. The power take-off gear and a brake is arranged at an output section of the planetary gearing. A on-off coupling which may be a gear coupling is arranged between the flywheel and the first shaft section.
A differential gear may be arranged to return part of the output ~rom the planetary gearing to an input section thereof and may be connected to a servo motor.

CA 0220~3l l997-0~-2l 23~86- 153 The slide drive may be provided with a load cell which detects any overload acting of the slide to transmit a signal from the load cell to the servo motor.
When the planetary gearing is arranged between the shaft sections as mentioned above, the rotational energy of the flywheel is transmitted through the first shaft section to the planetary gearing and is taken by the power take-off gear. By controlling rotation of a part of the planetary gearing, rotational velocity of the power take-off gear can be varied so that action velocity of the drive can be freely or arbitrarily controlled. Thus, the action velocity of the slide or the like can be controlled during a stroke of movement thereof.
When the variable torque brake is arranged, in place of a servo motor, at a part of the planetary gearing, the rotational velocity of a part of the planetary gearing can be controlled by the torque brake, which varies the rotational velocity of the power take-off gear so that action velocity of the drive can be freely controlled.
When the power take-off gear and the brake are provided at the output section of the planetary gearing driven by the servo motor and the rotational velocity of the servo motor is set to a calculated value with the drive being braked to stop, the rotational velocity of the first shaft section of the power transmission shaft can be made equal to that of the flywheel.
This makes it possible to employ a connector such as ~ear coupling between flywheel and the power transmission shaft which requires no consumables such as connection pads. Variation of the CA 0220~31 1997-0~-21 rotational velocity of the pQwer take-off gea~ can be attained by controlling the rotation of the output section of the planetary gearing by means of the servo motor so that action velocity of the drive can be freely controlled.
When the differential gear is provided to return part of the output of the planetary gearing to an input section thereof and is connected to the servo motor~ braking force required for the servo motor can be minimized.
When any overload is detected by the load cell, the servo motor may be tripped or driven at a predetermined rotational velocity to nullify overload.
In accordance with the present invention, there is provided in a power transmission for a mechanical press wherein rotational energy stored in a flywheel through driving of a main motor is taken through a power transmission shaft by a transmission gear and is transmitted to a slide drive, an improvement which comprises first and second shaft sections into which said power transmission shaft is divided and which are ad]acent to said flywheel and said power take-off gear~
respectively, a planetary gearing between the shaft sections adapted to be driven by a servo motor, said transmission gear being mounted on an output section of the planetary gearing and a load cell on said slide drive for detecting any overload acting on a slide, a signal from said load cell being transmitted to said servo motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMl3NTS
Preferred embodiments of the present inventlon will be described in con~unctlon with the drawings.
Figure 2 shows a first embodiment of the present lnvention and ls directed to a case where rotatlonal energy of a flywheel ls transmltted as drlving force to a slide. In power tran~mission for a mechanical press similar in structure to the conventional power transmission shown ln Figure 1, a power transmisslon shaft 4 is dlvided at a positlon between the flywheel 2 and the power take-off gear 5 into first and second shaft sections ad~acent to the flywheel 2 and the gear 5, respectlvely. Arranged between the shaft sections 4a and 4b is a planetary gearing 19 which comprises a sun gear 15, a planetary gear 13 and an internal-tooth ring gear 14 in mesh with one another in the order named. The sun gear lS is connected to the shaft sectlon 4a and a planetary c~rrier 20 of the planetary gear 13 is connected 5a CA 0220553l l997-05-2l to the shaft section 4b as power take-off shaft. A power take-off gear 5 is mounted on the second shaft section 4b so that the rotational energy of the flywheel 2 is transmitted from the first shaft section 4a through the planetary gearing 19 to the power take-off gear 5 where the power to be given to the slide drive 8 is taken. The ring gear 14 has at its outer periphery an external-tooth ring gear 16 attached thereto which is in mesh with a pinion 17. The pinion 17 is mounted on a shaft of a servo motor 18 such as AC servo motor. As a result, the servo motor 18 is driven to control rotation of the carrier 20 of the planetary gear 13 as output sect1on of the planetary gearing 19 so that rotation of the power take-off gear 5 on the second shaft section 4b in relation to the first shaft section 4a as input section can be varied to freely control action velocity of a slide 9 vertically displaced by a slide drlve 8. In Figure 2, the part~ similar to those in Figure 1 have the same reference numerals as those in Figure 1.
When the clutch 3 is engaged to the flywheel 2 being rotated by the main motor 1, the rotational energy of the flywheel 2 is taken through the clutch 3 by the first shaft sec:tion 4a and is transmitted through the planetary gearing 19 to the second shaft section 4b so that the power to be given to the slide drive 8 i.s taken by the power take-off gear 5 on the shaft ~ection 4b.
In this case, rotational veloaity of the planetary carrier 20 of the planetary gear 13 as output section of the planetary gearing 19 can be controlled by the servo motor 18 so that ro~ational velocity of the power take-off gear 5 can be freely controlled.

-Therefore, movement of the slide 9 vertically displaced by the drive 8 can be freely controlled.
The following equations apply:

Nd ~ Np ~ z ~ (NS ~ Np) (1) Z3 ~ Z1 Z2 = 2 '--~2) where N8 is rotational velocity of ~he first shaft section 4a;
Np is rotational velocity of ~he second shaft section 4b;
Nd is rotational velocity of the internal-tooth ring gear 14 of the planetary gearing 19 driven by the servo motor 18;
Zl is the number of teeth on the sun gear 15;
Z2 is the number of teeth on the planetary gear 13; and Z3 is the number of teeth on the ring gear 14.
Therefore, based on the equation (1; above, in a normal operation where Np ~ Ns, the rotational velocity of the internal-tooth ring gear 14 is to be controlled by the servo motor 18 such that Nd = Ns is satisfied.
When the servo motor 18 is stopped ~Nd ~ ~), the following is derived from the equation (1):

~ 3 Under such condition, the driving force is taken by the power take-off gear 5 and is transmitted to the slide drive 8.
When the press working is to be stopped, i.e., when the CA 0220553l l997-05-2l slide g is to be stopped (Np = o)~ based on the equation ~1), the rot~tional velocity of the ring gear 14 is to be controlled by the servo motor 18 such that the following is satisfied, Zl Nd - - Z X Ns Thus, according to the present invention, the rotational velocity of the planetary gearing 19 is controlled by the servo motor 18 so that the action velocity of the slide 9 can be freely controlled during a stroke of movement of the slide 9. Therefore, holding of pressing state for a cer~ain time interval after the press working may be carried out, which is especially effective in press working of material made of aluminum, and press working for different kinds of materials can be carried out non-limitatively.
In Figure 2, the internal-tooth ring gear 14 may be in mesh with a second planetary gear arranged coaxially and integral with the planetary gear 13. In this case, the following appliess Nd = (1 + 1 4 ) X N ~ Zl ~ ~4 N
23 ~ Z~ ~3 ~ Z~

where Z4 is the number of teeth of the second planetary gear.
Figure 3 shows a second embodiment of the present invention which is similar in structure to the first embodiment shown in Figure 2 except that the power take-off gear 5 is attached to an outer periphery of an inner-tooth ring gear 14 as output section of the planetary gearing 19, a carrier 21 for the ring gear 14 being connected through a hollow shaft 22 to the brake 11, the second shaft section 4b in connection with the planetary carrier 20 of a planetary gear 13 being adapted to be driven by the servo motor 18.
In the second embodiment, the following equation applies:

Nd = Np N~; (3) 1 t --- I t 3 Z3 Zl where N8 is rotational velocity of the first ~haft section 4a;
Nd is rotational velocity of the second shaft section ~b driven by the servo motor 18;
Np is rotational velocity of the internal-tooth ring gear 14 of the gearing 1~;
Zl is the number of teeth on the sun gear 15;
Z2 is the number of teeth on the planetary gear 13; and Z3 is the number of teeth on the ring gear 14.
Therefore, based on the equation (3), ln a normal operation where Np = N5, the rotational velocity of the planetary carrier 20 of the planetary gear 13 is to be controlled through the second shaft section 4b by the servo motor 18 5uch that the equation Nd ~ N5 is satisfied. When the servo motor 18 is stopped (Nd = ~)~ the following is derived from the equation ~3).

P ~
and under such condition the driving force is ~aken by the power take-off gear 5. When the press working is to be stopped (Np =
~ ) r based on the equation (3), the rotational velocity of the carrier 20 of the planetary gear 13 is to be controlled by the CA 0220553l l997-05-2l servo motor 18 such that the followlng equation is satisfied Zl Z1 + Z3 In Figure 3, the internal-tooth ring gear 14 may be in mesh with a second planetary gear arranged coaxial and integral with the planetary gear 13; alternatively, the power take-off gear 5 may be mounted on the hollow shaft 22. Then, the following equation applies:

1 t 1+ 2 ~2'Z3 Zl Z4 Figure 4 shows a third embodiment of the present invention which is similar to structure to the second embodiment shown in Figure 3 except that the first shaft section 4a is connected to the carrier 21 of the internal-tooth ring gear 14, the second shaft sectlon 4b being connected to the sun gear 15, the power take-off gear 5 and the brake 11 being mounted through the hollow shaft 22 on the planetary carrier 20 of the planetary gear 13, the planetary gear 13 acting as output section.
In the third embodiment shown in Figure 4, rotation of the planetary gearing 19 is controlled by the servo motor lB so that the action velocity of the slide 9 can be freely controlled just like the first and second embodiments respectively shown in Figures 2 and 3.
Also in Figure 4, the internal-tooth ring gear 14 may be in mesh with a second planetary gear arranged coaxial and integral with the planetary gear 13.

CA 0220553l l997-05-2l Figure 5 shows a fourth embodiment of the present lnvention which is similar in structure to the third embodiment shown in Figure 4 except that the planetary gear 13 is a first planetary gear, a second planetary gear 23 being coaxial and integral with the first planetary gear 13, the carrier 20 for the planetary gears 13 and 23 being connected to the first shaft section 4a, the second planetary gear 23 being in mesh with the internal-tooth ring gear 14, the carrier 21 of the ring gear 14 being mounted on the hollow shaft 22, the ring gear 14 acting as output section.
Figure 6 shows a fifth embodiment of the present invention which is similar to structure to the first embodiment shown in Figure 2 except that the planetary gear 13 is a first planetary gear, the second planetary gear 23 being arranged coaxial and integral with the first planetary gear 13, the internal-tooth ring gear 14 being in mesh with the second planetary gear 23 and the carrier 21 of the ring gear 14 being connected to the first shaft section 4a, the sun gear 15 being connected to the second shaft section 4b, the carrier 20 of the planetary gears 13 and 23 being connected to the hollow shaft 22 on the shaft section 4b, the pinion 17 driven by the servo motor 18 being in mesh with a gear 25 on the hollow shaft 22, the sun gear 15 acting as output section.
Figure 7 is a sixth embodiment of the present invention which is similar in structure to the first embodiment shown in Figure 2 except that the planetary gear 13 is a first planetary gear, a second planetary gear 23 being arranged coaxial and CA 0220~31 1997-0~-21 integral with the ~irst planetary gear 13, the internal-tooth ring gear 14 being in mesh with said second planetary gear 23, the sun gear 15 being connected to the second shaft section 4b the sun gear 15 acting as output section.
In the fourth to sixth embodiments shown in Figures 5 to 7, respectivèly, the similar effects and advantages as those in the first to third embodiments shown in Figures 2 to 4 will be obt.~ined.
Figures 8 to 13 show modi~ications of the first to sixth embodiments shown in Figures 2 to 7, respectively, where a planetary gearing 19' having a second sun gear 24 is used in place of ~he planetary gearing 19 having the internal-tooth ring gear 14.
More specifically, Figure 8 shows a seventh embodiment which is a modification and development of the first embodiment shown in Figure 2. Arranged between the shaft sections 4a and 4b is the planetary gearing 19' having the first and second sun gears 15 and 24 and the first and second planetary gears 13 and 23 coa~ial and integral with each other and respectively in mesh with the gears 15 and 24, the first sun gear 15 being connected to the fir~t shaft section 4a, the second sun gear 24 being connected to an end of the shaft section 4b, the carrier 20 of the planetary gears 13 and 23 being connected to the hollow shaft 22 on the second shaft section 4b, the power take-off gear 5 and the brake 11 heing mounted on the hollow shaft 22, the other end of the shaft section 4b being connected to the servo motor 18.
In the above, the following applies:

CA 0220~31 1997-0~-21 Nd = X l~p t X hs 1 _ ~i'Z4 Z2 75 Z~ z5 where Ns is rotational velocity of the first shaft section 4a;
Nd is rotational velocity of the second shaft section 4b by the servo motor 18;
Np is rotational velocity of the hollow shaft 22 which is a common rotational velocity of the planetary gears 13 and 23 as output section;
Zl is the number of teeth of the first sun gear 15;
Z2 is the number of teeth of the first planetary gear 13;
Z4 is the number of teeth of the second planetary gear 23;
and Z5 is the number of teeth of the second sun gear 24.
Therefore, the action velocity of the slide 9 can be freely controlled by controlling the rotational velocity of the servo motor 1~.

Figure 9 shows an eighth embodiment of the present invention which is a modification and development of the second embodiment shown in Figure 3. Arranged between the first and second shaft sections 4a and 4b is the planetary gearing 19' having the first and second sun gears 15 and 24 and the coaxial and integral planetary gears 13 and 23 in mesh with the sun gears 15 and 24, the sun gears 15 and 24 being respectively connected to the shaft sections 4a and 4br the rotational energy of the flywheel 2 being transmitted from the first shaft section 4a thr~ugh the planetary gearing 19' to the power take-off gear 5, CA 0220553l l997-05-2l the power to be given to the slide drive 8 being taken by the gear 5, the gear 25 being mounted through the hollow shaft 22 on the carrier 20 of the planetary gears 13 and 23, a shaft 2~ of the pinion 17 in mesh with the gear 25 being connected to a variable torque brake 28 which is adapted to be actuated by instructions from a control unit 27. The rotational velocity of the gear 5 can be varied through the sun gear 24 a~ output section by controlling the common rotational velocity of the planetary gears 13 and 23 through actuation of the variable torque brake 28 to thereby freely control the action velocity of the slide 9 vertically displaced by the slide drive 8.
The control unit 27 comprises a brake controller 30, which is adapted to receive a feedback signal from a rotary encoder 29 as speedmeter on the shaft 26 of the pinion 17 and which sends a drive signal to the variable torque brake 28, and a press controller 33 which sends an action signal to the brake cont;roller 30 on the basis of signals from rotary encoders 31 and 32 as speedmeters respectively on the shaft sections 4a and 4b.
In the eighth embodiment shown in Figure 9, when the clutch 3 is engaged to the rotational flywheel 2 driven by the main motor l, the rotational energy of the flywheel 2 is taken through the clutch 3 by the first shaft section 4a and is transmitted through the planetary gearing 1~' to the second shaft section 4b, the power to be given to the slide drive 8 being taken by the power take-off gear 5 on the second shaft section 4b. In this case, the common rotational velocity of the plane1;ary gears 13 and 23 of the planetary gearing l9' can be controlled by the .

vari.able torque brake 28 so that the rotational velocity of the power take-off gear 5 can be freely varied. Therefore~ the movement of the slide 9 vertically displaced by the slide drive 8 can be freely controlled during a stroke of movement of the slide 9. Based on the rotational velocity of the first shafl; secti~n 4a detected by the rotary encoder 31, the press controller 33 sends instructions to the brake controller 30 which in turn send~
instructions to actuate the variable torque brake 28 to thereby control the common rotational velocity of the planetary gears 13 and 23 of the planetary gearing 19' and vary the rotat:lonal velocity of the power take-off gear 5 through the sun gear 24 as output section. The rotational velocities of the pinion 17 and power take-off gear 5 detected respectively by the rotary encoders 29 and 32 are respectively fedback to the brake controller 30 and press controller 33.
In the above, the following equation applies Nd ~ ~p x z ~ 5 Z~Zs Zl'Z4 where Ns is rotational velocity of the first shaft section 4a;
Np is rotational velocity of the second shaft section 4b;
Nd is the common rotational velocity of the planetary gears 13 and 23, i.e. the rotational velocity of the hollow shaft 22;

Zl is the number of teeth of the first sun gear 15;
Z2 is the number of teeth of the first planetary gear 13;
Z4 is the number of teeth of the second planetary gear 23;

and Z5 is the number of teeth of the second sun gear 24.
Therefore, based on the above equation, in a normal operation, the equation Np ~ Ns will be satisfied by controlling the common rotational velocity of the planetary gears 13 and 23 by the variable torque brake 28 such that Nd ~ Ns When the brake 28 is completely engaged (Nd - 0), based on the above equation, Np ~ Ns ~ 1 4 Z2 ~5 and under such condition the power is taken by the power take-off gear 5 and is transmitted to the slide drive 8.
When the press working is to be stopped, i.e., when the slide g i~ to be stopped, the relation Np ~ o is obtained by controlling the common rotational velocity of the planetary gears 13 and 23 by means of the variable torque brake 28 suc~h that ~d = Ns x Z2 ~5 ~ 4 Thus, in the eighth embodiment shown in Figure 9, the rotation of the planetary gearing 19' is controlled by the variable torque brake 28 so that the action velocity of the slide 9 can be freely controlled in a stroke of movement of the slide 9.
As a result, a pressing state can be held for a certai.n time interval after press working, which is especially effective for press working of material made of aluminum; after press working, pressing parts can be returned to their waiting or inoperative position; and press working can be effected non-limitatively for CA 0220~31 1997-0~-21 different kinds of materials. Moreover, it is advantageous in efficiency.
In Figure 9, the servo motor 18 may be used in place of the varlable torque brake 28.
Figure 10 shows a ninth embodiment of the present invention which is a modification of the third embodiment shown in Figure 4 and which is similar in structure to the seventh embodiment shown in Figure 8 except that positions of the first and second sun gears 15 and 24 are reversed and positions of the first and second planetary gears 13 and 23 are reversed. More specifically, the first sun gear 15 in mesh with the first planetary gear 13 i~ connected to the second shaft sec~ion 4b while the second sun gear 24 in mesh with the second planetary gear 23 i~ connected to the first shaft section 4a.
The ninth embodiment shown in Figure 10 also has the same effects and advantages as those obtained in the seventh embodiment shown in Figure 8.
Figure 11 shows a tenth embodiment of the present invention which is a modification and development of the four~h embodiment shown in Figure 5. In order to transmit the rotational energy of the flywheel 2 to the power transmission shaft 4, arranged between the flywheel 2 and the first shaft section 4a is a gear coupling comprising a ring gear 34 contiguous with a side edge of the flywheel 2, a gear 35 opposed to the gear 34 and attached to the first shaft section 4a and an internal--tooth ring 36 adapted to be axially moved between outer peripheries of the gears 34 and 35 for connection and disconnection of the gears 34 ~ - ~ =
CA 0220~3l l997-0~-2l and 35 with each other, so that the rotation of the flywheel 2 is transmitted through the gear coupling 37 to the power ~ransmission shaft 4.
The planetary gearing 19' is arranged between the shaft sect;ions 4a and 4b. The carrier 20 of the planetary gears 13 and 23 is connected to the first shaft section 4a. The first sun gear 15 is connected to one end of the second shaft section 4b. The pow~r take-off gear 5 is mounted through the hollow shaft Z2 on the second sun gear 24. The servo motor 18 is connected to the other end of the second shaft section 4b. As a result~ the rotation of the power take-off gear 5 can be controlled through the planetary gearing 19' by the servo motor 18. The hollow shaft 22 i~ provided with the brake 11.
Now, with the flywheel 2 belng separated froM the first shaft section 4a by the gear coupling 37, the main motor 1 is driven at a predetermined rotational speed while rotation of the second sun gear 24 as output section of the planetary gearing 19' is stopped through the hollow shaft 22 by the brake 11. When the servo motor 18 is driven under such conditions, the planetary gears 13 and 23 are rotated in unison around the sun gears 15 and 24 and the first shaft section 4a is rotated. The rotational velocity of the servo motor 18 is controlled such that the first shaft section 4a is rotated at the same rotational velocity as that of the flywheel 2. In this case, the gears 34 and 35 can be interconnected without difficulty since they are rotated at the same rotational velocity. Upon start of press working~ the brake 11 is disengaged and the servo motor 18 is controllingly driven so .. ..

that the first sun gear lS is rotated to control the rotation of the planetary gears 13 and 23 and the rotation transmitted from the second sun gear 24 through the hollow shaft 22 to the power take-off gear 5 can be freely varied.
In the above, the following equation applies:

Nd = x Np - ~ - I) X Ns where Ns is rotational velocity of the first shaft section 4a;
Nd is rotational velocity of the second shaft section 4b;
Np is rotational velocity of the second sun gear 24 as output section of the planetary gearing l9';
Zl is the number of teeth of the first sun gear 15;
Z2 is the number of teeth of the first planetary gear 13;
Z4 is the number of teeth of the second planetary gear 23;
and Z5 is the number of teeth of the second sun gear 24.
Therefore, the movement of the slide 9 vertically dis1?laced by the slide drive 8 can be freely controlled by con1:rolling Nd. More specifically, upon start of the operation, the flywheel 2 is rotated to have a predetermined velocity Ns under the conditions that the gear coupling 37 is off and the brake ll is on Then, the servo motor 18 ls rotated wlth a value Nd which satisfies the equation Np ~ 0. In thi~ case, the press wor}cing is being stopped because of the brake ll being on and the first shaft section 4a is rotated at the same velocity as Ns.
Since the flywheel ~ has the same velocity as the first shaft CA 0220~3l l997-0~-2l section 4a, the gear coupling 37 can be actuated to interconnect the gears 34 and 35 with no mechanical shock in this state. Thus, preparation of the operation is completed. Upon starting of the worklng, the brake 11 is released and at the same time the servo motor 18 is actuated to make Nd change toward a predetermined value Np. Thus, the slide 9 is smoothly started moving.
In this manner, in the tenth embodiment sho~n in Figure 11, driving and stopping of the slide ~ upon starting of the press working can be made by the operation of the servo motor 18 and the brake 11 so that the flywheel 2 can always be connected to the first shaft section 4a. As a result, the gear coupling 37 which re~uires no connection pads can be used between the flywheel 2 and the power transmission shaft 4.
Figures 12 and 13 respectively show eleventh and twelfth embodiments of the present invention which are modifications of the fifth and sixth embodiments shown in Figures 6 ancl 7, respectively. The eleventh embodiment shown in Figure 12 is similar in structure to the eighth embodiment shown in Figure 9 except that the first sun gear 15 is connected to the second shaft section 4b and the second sun gear 24 is connected to the first shaft section 4a. In the twelfth embodiment shown in Figure 13, the first sun gear 15 is connected to the second shaft section 4b, the second sun gear 24 being mounted on the hollow shaft 22, the caxrier 2~ of the planetary gears 13 and 23 being connected to the first shaft section 4a.
The eleventh and twelfth embodiments respectively shown in Figures 12 and 13 also have similar effects and ad~antages to CA 0220553l l997-05-2l ~ 23986-153 those in the other embodiments.
Here, with re~erence to the above-mentioned first to twelfth embodiments respectively shown in Fiyures 1 to 13, combinations of the respective gears of the planetary gearing with the shafts of the servo motor 18, flywheel 2 and power take-off gear 5 are as shown in Table 1 below. In Table 1, R denotes the internal-tooth ring gear 14; P, at least one of the planetary gears 13 and 23; S1, the first sun gear; and S2, the second sun gear 24.
Table l shaft of shaft of shaft of servo motor flywheel power ta]ce-off gear 1st embodiment R Sl P
2nd embodiment P S1 R
3xd embodiment Sl R P
4th embodiment Sl P R
5th embodiment P R S
6t:h embodiment R P S
7th embodiment S2 1 P
81h embodiment P Sl S2 9t:h embodiment Sl 2 lOt:h embodiment Sl P S2 11th embodiment P S2 S
12th embodiment S2 P S

CA 0220~31 1997-0~-21 Figure 14 shows flows of electric power by arrows a, b an~ e and flows of mechanical power by arrows c and d during the operation of the tenth embodiment shown in Fi~ure 11. More specifically, for example, in low-velocity press worki.ng, all of the energy from the flywheel 2 is not consumed and most thereof is made into electric power and ~s returned to the power source so that the braking force of the servo motor 18 is greater. In this case, suppose that power (arrow al of the main motor 1 is 1 kw.
The~n, power (arrow b) of the servo motor 18 is 0 kw and the power (arrow c) from the flywheel 2 to the planetar~ gearing lg' is ad~ed with powers of and back to the main motor 1 and amounts to 77 kw. Let the power (arrow d) taken by the power take-off gear 5 an~ transmitted to the slide be 1 kw, then the power returned to the power source by the servo motor 18 is 76 kw and the servo motor 18 will require power of 76 kw. When the slide is to be stopped at its lower dead point, the power for d is 0 kw so that the power for e is 77 kw (maximum). In the press working with deceleration to 1/2, power distribution is 46.2 kw for a, 0 kw for b, 77 kw for c, 46.2 kw for d and 30.8 kw for e so that the servo motor i8 requires the power of 30.8 kw. Furthermore, in operation with no deceleration (i.e., normal press working with no acceleration and deceleration), the power distribution is 77 kw for a, 15.4 kw for b, 77 kw for c and 92.4 kw for d (which is sum of the power from b with the power from c).
In view of the above respective operational modes, in the lower-velocity press working, the electric power of 76 kw as maximum is returned from the servo motor 18 to the power source so CA 0220~31 1997-0~-21 that the servo motor 18 is braked with larger torque corresponding to such maximum, which requires the servo motor to be larger-si~ed.
Then, a fourteenth embodiment shown in Figure 15 is devised to minimize the braking force required for the servo motor 18. In this embodiment, energy from the flywheel 2 is returned as me~hanical energy unlike the tenth embodiment where it is returned as electric energy. In order to return the mechanical power taken from the output section of the planetary gearing 19' to the input section, arranged adjacent to the first shaft section 4a as input side of the planetary gearing 19' is a differential gear 40 wlth its side gear shafts 38 and 39 being in parallel with the first shaft section 4a. A power transmission gear 41 is in mesh with the power take-off gear 5. A drive gear 43 is mounted on a shaft 42 on which the power transmission shaft 41 is also mounted. The drive gear 43 is in mesh with a carriage gear 44 of the differential gear 40. One of the side gears, i.e., the side gear 38 is connected to the servo motor 18 while a pinion 45 is mounted on the other side gear 39. A gear 46 is arranged midway of the first shaft section 4a and is in mesh with the pinion 45.
In the fourteenth embodiment shown in Figure 15, part of the mechanical power taken at the output side of the ~lanetary gearing 19' by the power take-off gear 5 is returned through the transmission gear 41, the shaft 42, the drive gear 43, the di:Eferential gear 40, the pinion 45, the gear 46 and the first shaft section 4a to the planetary gearing 19' so that the servo motor 18 may be of minlmum power for velocity control by optimally selecting the deceleration ratio.

CA 0220553l l997-05-2l More specifically, in the above, in lower-velocity press working, let the power distribution be 0 kw for a and b, 46.2 kw for c and 1 kw for d. Then, 76 kw of power mechanically returned from the power take-off gear 5 to the differential power 40 alon~
arrow f is distributed by the differential gear 40 so that 30.8 kw of mechanical power is returned along arrow g to the planetary gearing 19' and 45.2 kw of electric power is returned from the servo motor 18 along arrow e to the power source. Therefore, the sum of the powers of c and g is fed to the planetary gearing 19', the power of 1 kw being consumed for d, the remaining power of 76 kw being mechanical power returned to the differential gear 40.
This means that, for the servo motor 18 which requires 76 kw in the twelfth embodiment shown in Figure 13, power of 45.2 kw will suffice. In the press working with deceleration to 1/2, let the power distribution be 46.2 kw for a, 0 kw for b, 46.2 kw for c and 46.2 kw for d. Then, the power of 30.8 kw for f mechanically returned from the planetary gearing 19' to the differential gear 40 .ts circulated through g so that the power for e is 0 kw and the power of the servo motor becomes zero. In an operation with no deceleration, the power of 46.2 kw for a is transmitted through c to d and the power of 46.2 kw for b is distributed at the differential gear 40 into 15.4 kw for f (in the direction reverse to the above-mentioned case) and 30.8 kw for g and summed with the value for c to become 92.4 kw for d. Therefore, the power for e is () kw.
As is clear from the above, even in view of all the operation modes, in contrast to the case of the thirteenth embodiment shown in Figure 14 where the maximum power required is 77 kw, the fourteenth embodiment shown in Figure 15 will do with maximum power of 46.2 kw and the servo motor 18 with the capacity of 60% will suffice.
With respect to the fourteenth embodiment shown in Figure 15, description has been made such that the input and ou~put sections of the differential gear 40 and the connection to the~ servo motor 18 are the carriage gear 44, the side gear 39 and the side gear 38, respectively. However, these relati.onships may be freely interchangeable.
Figure 16 shows a fifteenth embodiment of the present invention which is substantially similar in structure to the tenth em~lodiment shown in Figure 11 further compri~ing a load cell 48 on a ~rank lever 47 of the slide drive 8 for detecting reaction load act.ing on the slide 9. The load cell 48 is connected to a controller 49. When any overload i5 detected hy the load cell 48, in~tructions are sent from the controller 49 to the servo motor 18 to trip the motor 18. Reference numeral 50 denotes a main gear for the slide drive 8; and 51, a crank arm.
According to this embodiment, in the conditi.on that press action is given at a predetermined velolity by the servo motor 18 to the slide 9, a signal representative of the load detected by the load cell 48 is fed to the controller 49; when it is judged to be an overload, then instructions are fed from the controller 49 to the servo motor 18 so as to trip the motor 18.
Since the servo motor 18 is tripped, any overload will not act on the die and/or slide drive 8, there~y protecting the CA 0220~31 1997-0~-21 machinery.
In the above, combination of the planetary gearing 19', the servo motor 18 and the load cell 48 which protects the machinery are non-hydraulic systems. In comparison with the prior art having hydraulic means as countermeasure to any overload, the present invention is much simplified in structure and greatly ~facilitates maintenance.
It is to be understood that the present invention is not limited to the embodiments described above and that various modification may be made within the true spirit of the present invention. For example, the gear coupling 37 of the tenth embodiment shown in Figure 11 may also be applied in the other embodiments. In the above, description has been made on control of the slide drive 8 only; to transmit the power to the work conveyance drive 12 (see Figure 1) may be made on the basis of the output result of the power transmission according to the present invention or alternatively it may be also controlled in a similar manner. In the fifteenth embodiment shown in Figure 16, description is made of the case where, when any load detected by the load cell 48 is an overload, the servo motor 18 is tripped by the controller 49; instead, the servo motor 18 may be driven at a rotational speed such that press velocity becomes zero.
As mentioned above, according to a power transmission for a mechanical press in accordance with the present invention, arranged between shaft sections of ~he power transmission shaft for transmitting rotational energy of the flywheel is a planetary gearing adapted to be driven by a servo motor. A power take-off CA 0220~31 1997-0~-21 ~ 23986-153 gear is mounted on an output section of the planetary gearing so that rotation of the output section of the planetary gearing can be freely controlled by the servo motor and the rotational ve].ocity of the power take-off gear can be varied. As a result, for example, when the slide is actuat~d through a sli~e drive, the act;ion velocity of the slide can be freely controlled during a stroke of movement of the slide, which allows holding of a stopped state at the lower dead point of the slide which in turn is effective for press working of aluminum material. Versatility is attained for press working of different kinds of materials. When a planetary gearing with a variable torque brake is arranged between shaft sections of a power transmissio~ shaft, rotation of an output section of the planetary gearing can be freely controlled, so that rotational velocity of a power take-off gear can. be varied and therefore the action velocity of a slide can be controlled just like the above case. With a planetar~ gearing being arranged between shaft sections of a power transmission shaft and adapted to be driven a servo motor, arranged on an output section of the planetary gearing are a power take-off gear for transmission of driving force to a drive as well as a brake, so that rotation of the output section of the planetary gearing can be freely controlled by the servo motor and rotation of the output section may be stopped by the brake, which allows use of an on-off coupling such as gear coupling between the flywheel and power transmission shaft which coupling requires no consumable parts and which can be preliminarily connected. As a result, no mechanical shock will occur upon transmission of power; no exchange for consumables is required and therefore press working free from maintenance for consuma~les can be carried out and reduction in cost in press working can be attained. ~hen a dif.ferential gear is used to return part of the output of the planetary gearing to an input side and is connected to a servo motor, any required braking force of the servo motor can be minimized. This is advantageous in that the ~ervo motor may be of smaller size. Provision of a load cell on a slide drive for de~ecting any overload makes it possible to trip a servo motor or to drive it at a required rotational velocity upon detection of any overload by the load cell so as to protect the machinery just lih:e the prior art having hydraulic means for countermeasure to any overload. As a result, in comparison with the prior art having hydraulic means for countermeasure to any overload, the present invention is simplified in structure ,and facilitates maintenance.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a power transmission for a mechanical press wherein rotational energy stored in a flywheel through driving of a main motor is taken through a power transmission shaft by a transmission gear and is transmitted to a slide drive, an improvement which comprises first and second shaft sections into which said power transmission shaft is divided and which are adjacent to said flywheel and said power take-off gear, respectively, a planetary gearing between the shaft sections adapted to be driven by a servo motor, said transmission gear being mounted on an output section of the planetary gearing and a load cell on said slide drive for detecting any overload acting on a slide, a signal from said load cell being transmitted to said servo motor.
CA002205531A 1992-03-16 1993-03-16 Power transmission for mechanical press Expired - Lifetime CA2205531C (en)

Priority Applications (11)

Application Number Priority Date Filing Date Title
JP4-89259 1992-03-16
JP8925992 1992-03-16
JP30794692 1992-10-23
JP4-307946 1992-10-23
JP4-317962 1992-11-04
JP31796292 1992-11-04
JP4-358010 1992-12-25
JP35801092A JP3484714B2 (en) 1992-12-25 1992-12-25 Driving force transmission device for mechanical press
JP03239593A JP3326844B2 (en) 1992-03-16 1993-01-29 Driving force transmission device for mechanical press
JP5-32395 1993-01-29
CA 2091747 CA2091747C (en) 1992-03-16 1993-03-16 Power transmission for mechanical press

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CA 2091747 Division CA2091747C (en) 1992-03-16 1993-03-16 Power transmission for mechanical press

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CA2205531A1 CA2205531A1 (en) 1993-09-17
CA2205531C true CA2205531C (en) 2002-01-15

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CA002205494A Expired - Lifetime CA2205494C (en) 1992-03-16 1993-03-16 Power transmission for mechanical press

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CA002205494A Expired - Lifetime CA2205494C (en) 1992-03-16 1993-03-16 Power transmission for mechanical press

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CA (2) CA2205531C (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1930149A1 (en) * 2006-12-05 2008-06-11 Burkhardt GmbH Maschinenfabrik drive for eccenter press

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1930149A1 (en) * 2006-12-05 2008-06-11 Burkhardt GmbH Maschinenfabrik drive for eccenter press

Also Published As

Publication number Publication date
CA2205494A1 (en) 1993-09-17
CA2205494C (en) 1999-11-16
CA2205531A1 (en) 1993-09-17

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