Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C21/00—Flasks; Accessories therefor
  • B22C21/12—Accessories
  • B22C21/14—Accessories for reinforcing or securing moulding materials or cores, e.g. gaggers, chaplets, pins, bars
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
  • B22D15/02—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor of cylinders, pistons, bearing shells or like thin-walled objects
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D19/00—Casting in, on, or around objects which form part of the product
  • B22D19/0009—Cylinders, pistons
  • B22D19/0027—Cylinders, pistons pistons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D47/00—Casting plants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J15/00—Gripping heads and other end effectors
  • B25J15/0052—Gripping heads and other end effectors multiple gripper units or multiple end effectors

Definitions

• the invention relates to an automated method and plant for manufacturing pistons. More precisely the invention relates to an automated method and plant for treating by aluminizing ring-shaped inserts and for placing thereafter said rings in a chill for forming pistons, particularly of internal combustion engines, compressors, etc...
• the industrial production of pistons for internal-combustion engines is currently carried out with two processes quite different from each other: - by casting in a chill (the molten aluminum alloy is casted in a metallic die); -by hot-pressing (pistons are forged -it is also said that pistons are swaged- by approaching the lump of pre-heated material with a die and a half-die, then by pressing it with pressures of about some thousand of tons).
• the molten pistons are normally used for mass-production of internal- combustion engines and the present invention relates to the first kind of process.
• aluminum alloy pistons are generally mounted which are reinforced with centrifuged cast iron inserts. Said inserts are incorporated near the first and/or second piston ring seat during the casting.
• said inserts Before being placed in the chill for cast forming the pistons, said inserts generally undergo an aluminizing process named "Alfin" process.
• the aluminizing consists in dipping the inserts in a molten aluminum bath for a time ranging from 2 to 4 minutes.
• An object of the present invention is providing an automated method and plant for manufacturing pistons, in particular for treating the ring-shaped inserts and for placing thereafter the rings in a chill, during the phase of preparing the die for casting the pistons.
• Another object of the invention is providing an automated method and plant, for treating and placing thereafter the rings in a chill, that allows using the robot units currently used in several industrial assembling processes and that is therefore economically advantageously to be industrialized.
• the plant and the method according to the invention it is possible carryng out a fast and fully automated production of pistons.
• a portion of the surface of said bath is freed from oxides so that the characteristics of the ring coating are not altered.
• Figure 1 is a plan top view of a plant according to the invention.
• Figure 2 is a side view of the loading station;
• Figure 3 is a side view of the aluminizing station;
• Figure 4 is a front view of the casting station
• Figure 5 is a side view of the aluminizing station during the bath cleaning
• Figure 6 is a view of a detail of the aluminizing station
• Figure 7 is a side view of the gripper assembly for picking the rings up;
• Figure 8 is a section view of a ring.
• a ring-like insert or ring 10 is shown in cross-section, the ring being made of pre- worked centrifuged cast iron that must be placed in the die or chill in which the pistons are formed by casting molten metal.
• a molten metal bath typically aluminum or an alloy thereof, in which the rings 10 are dipped;
• an anthropomorhic robot 51 is also shown for picking up and transferring the rings 10 from a station to another station in the plant.
• Said robot 51 is provided with a base 53 and an articulated revolving arm 55 and is able to reach all the stations of the plant with the end 57 of said arm 55.
• the end 57 of said arm 55 is provided with a pair of pneumatically driven pick ⁇ up devices. More precisely, said devices comprise a first pneumatically driven pick-up device 59 provided with a plurality of grippers 61 and a second pneumatically driven pick ⁇ up device 63 provided with a single gripper; the purpose of said pick-up devices will become more evident from the following description.
• Said station 11 comprises a pair of stores 13 comprising two cylindrical vertical parallel columns inside of which unfinished rings 10 - that is, rings that did not undergo the aluminizing treatment yet- are arranged in a stack.
• a pneumatic extraction device 15 horizontally arranged below stores 13 and provided with a pick-up head 17 allows extracting rings 10 one by one from the lower part of the stores 13 with a guillotine mechanism and putting them on a loading platform 19 arranged at the left of stores 13 in the Figure. Due to the thrust of the pick-up head 17, a pair of rings 10, extracted from the two stores 13, are simultaneously put on the loading platform 19 and can be removed from the loading station 11, as it will appear more evident from the description of the working cycle of the plant according to the invention.
• said station 11 is provided with a chute 12 where rings 10 can be unloaded if the picking up operation has to be interrupted for any reason.
• Said chute 12 ends in a collecting basin (not shown) from which said not treated rings 10 can be recovered with known means.
• a basin 14 containing a bath of liquid graphite is also provided at the front relative to said loading platform 19, between said platform 19 and the top of chute 12.
• the purpose of said graphite bath will become clearer from the following description.
• a molten metal bath is provided, preferably aluminum or an alloy thereof.
• Said station 21 comprises a crucible 23 containing the molten aluminum in which rings 10 are dipped for undergoing the aluminizing treatment.
• Said rings 10 are arranged on a support 71 provided with four hooks 79, one for every ring 10.
• said support 71 cpmprises an upper suspension rod 73 the lower part of which ends with a crosspiece 75.
• an upper suspension rod 73 the lower part of which ends with a crosspiece 75.
• two parallel lower rods 77 are fixed, each of which provided with a pair of corresponding hooks 79 arranged at different levels along said lower rods 77.
• a cylindrical suspension metal ring 72 is provided by means of which said support 71 can advantageously be kept suspended on a suitable support.
• a rack bracket 81 mounted in a cantilever way on an arm 83 -preferably revolving so as to allow reaching the crucible 23- is provided at the second station 21 in order to allow a plurality of said supports 71 to be hung at such level that the lower part of said supports 71, to which said rings 10 are hung, is dipped in the molten aluminum bath.
• the residence time of the rings in the aluminum bath is of approximately 180- 240 sec. therefore it is possible to use the same bath for treating some sets of four rings in fast sequence .
• the bracket 81 is provided with four or five U-shaped seats 82 for a corresponding number of supports 71.
• the third exchange station 31 is shown comprising an upright 33 on the top of which an U-shaped seat 35 is provided for hanging, by means of said suspension metal ring 72, one of said supports 71 before and after the aluminizing treatment.
• the fourth casting station 41 is shown in detail, wherein the rings 10 which previously underwent the aluminizing treatment are placed by groups of four in a chill 43 which will be subsequently covered for casting the piston bodies according to the prior art.
• the placing time of the inserts in the chill is lower than 25 sec.
• the second aluminizing station 21 is partially shown again during the phase preceding the exit of the support 71 with the respective rings 10 from the molten aluminum bath.
• the arm 55 of the anthropomorhic robot 51 by means of the second pneumatic pick-up device 63 provided with a single gripper 64, picks a tool 91 up from one of the seats provided on the rack bracket 81.
• the tool 91 comprises a handle 93 -in the present description also referred to as "first handle 93" - at the lower part of which a shovel 95 is fixed, said handle 93 being provided with a cylindrical metal ring 97 for allowing said tool 91 to be hung to one of the seats in said rack bracket 81.
• the robot 51 dips partially the tool 91 in the molten aluminum bath and collects the oxide layer that formed on the surface by combining a translation and a rotation movement, creating thereby in said bath an "exit window" for one of the supports 71 that are dipped in the crucible 23.
• the robot 51 arranges for the tool 91 to be placed again in the seat from which it has been picked up on the rack bracket 81.
• a U- shaped support 92 is provided for a second tool 94 to be used for collecting and removing from the aluminum bath oxides and films that formed on the surface thereof.
• Said tool 94 comprises a handle 96 - also referred to as, in the present description, "second handle 96"- to the lower end of which a showel 98 is fixed, having a shape substantially rectangular and arched along a circumference parallel to said handle 96.
• Said handle 96 is also provided with a cylindrical metal ring 99 that allows the support tool 94 to be hung to said support 92.
• the oxides and films that are formed in the aluminum bath can be collected at the surface, removed from the crucible 23 and discharged in a container 100 arranged beside said crucible 23 in said aluminizing station 21.
• the pneumatically driven pick-up device 59 is shown which is provided with a plurality of grippers 61 for picking up and transferring a set of four rings 10 at a time.
• the pick-up device 59 comprises an aluminum support 65 fastened to the wrist of the end 57 of the arm 55 of the anthropomorhic robot 51, on which four pneumatic grippers 61 are mounted aligned.
• Each pneumatic gripper 61 is provided with three gripping teeth 67 arranged parallel and at angles of 120° relative to each other, and radially displaceable.
• Said teeth 67 are suitable for engaging with the inner circumference of said ring 10, driven by the pneumatic control of the gripper 61.
• the two central grippers 61 are not movable while the two external grippers 61 are movable, slidable on nitrided guides and driven by pneumatic cylinders; in particular two external grippers 61 can slide at least in a direction lateral to themselves relative to the support 65.
• the driving of the grippers 61 is carried out by means of two electro valves arranged in the pneumatic circuit, a first of said electrovalves used for driving two of said grippers, the second electro valve used for driving the other grippers.
• Such separate handling is due to the fact that the steps of taking rings 10 from the first station 11 and from the support 71 when it is in the third exchange station is made by pairs.
• each gripper 61 is provided with three telescopic pins 69 supported by springs and parallel to said teeth 67, they also arranged at angles of 120° and suitable for allowing an optimal positioning of the rings 10 in the chill thanks to the spring thrust in an axial direction relative to said rings 10.
• the operating cycle of the plant according to the invention and, consequently, the method according to the invention for treating and inserting the rings 10 in the chill will be now described in detail.
• the anthropomorhic robot 51 picks the tool 91 up with the pneumatic gripper 64 and cleans the surface of the aluminum bath in the crucible 23 with the corresponding shovel 95, removing the oxides and films and freeing therewith an exit zone for the rings 10.
• the robot 51 picks up one of the supports 71 that are hanging from the rack bracket 81 at the second aluminizing station 21, from which rack bracket four rings 10 are in turn hanging that underwent the aluminizing treatment.
• Said support 71 is picked up with the pneumatic membrane gripper 64 and by taking the support 71 out from the bath in the crucible 23 from the area previously freed from oxides.
• the support 71 is then laid on the seat 35 in the third exchange station 31.
• the robots 51 pick four rings 10 up two by two from the support 71 that is in the third exchange station 31 and puts them immediately - that is, substantially without further waiting-, working- or handling steps - in the chill in the fourth casting station 41. After having put the rings 10 in the chill 43, the robot 51 reaches the first station 11 for picking up a new set of four unfinished rings 10.
• the picking up of rings 10 from the station 11 is made two by two on the loading platform 19 by means of the pneumatic grippers 61.
• the robot 51 picks the support 71 carrying the rings 10 up from the support 35 with the pneumatic gripper 63 and lays it down in the same position where it previously was in the rack support 81 at the second aluminizing station 21. When the robot 51 returns in waiting position, the cycle is over.
• the operating cycle of the plant according to the invention may provide for carrying out several steps which are important for the good outcome of the whole process.
• the anthropomorhic robots 51 dips the gripping teeth 67 of grippers 61 in the basin 14 containing liquid graphite. This operation is important since facilitates separation of ring-like inserts 10 from the gripper 61 itself when said rings 10 are put on the support 71.
• the robot 51 In case of unexpected anomaly on the fourth casting station 41 the robot 51, if it has already picked the rings 10 up, carries the "abort" operation out unloading said rings on the proper unload chute 12 provided in the station 11.
• robot 51 periodically - as an example after 8-10 complete cycles- picks the tool 94 up from the support 92 with the gripper 64 and carries out the operation of collecting the oxides and films from the bath discharging them in a suitable container 100.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Robotics (AREA)
• Coating With Molten Metal (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=35501028

Family Applications (1)

Country Status (3)

Families Citing this family (5)

Family Cites Families (5)

• 2004
  • 2004-07-09 IT ITTO20040471 patent/ITTO20040471A1/it unknown
• 2005
  • 2005-06-29 EP EP05757596A patent/EP1776213A2/de not_active Withdrawn
  • 2005-06-29 WO PCT/IB2005/001948 patent/WO2006008607A2/en not_active Ceased

Non-Patent Citations (1)

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