U.S. patent application number 10/580826 was filed with the patent office on 2007-04-12 for method and apparatus for molding by forging.
This patent application is currently assigned to HONDA MOTORS CO., LTD.. Invention is credited to Yoshihisa Doi, Koichi Goto, Shoji Matsumoto, Masayoshi Sakakibara.
Application Number | 20070079641 10/580826 |
Document ID | / |
Family ID | 34635605 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070079641 |
Kind Code |
A1 |
Doi; Yoshihisa ; et
al. |
April 12, 2007 |
Method and apparatus for molding by forging
Abstract
The invention is directed to provide a forming method and a
forming apparatus that are, without extending a processing time
compared with the conventional practice, capable of sufficiently
lubricating a formed object and forming at safety without the
lubricant igniting under pressure. In an extruding apparatus, a
workpiece is successively transferred to a series of press stages,
a conveying unit successively transferring the workpiece is
provided with a nozzle for spraying the workpiece with lubricant,
and the workpiece and the nozzle are located in fixed relative
positions to each other in spraying the workpiece with the
lubricant.
Inventors: |
Doi; Yoshihisa;
(Tochigi-ken, JP) ; Sakakibara; Masayoshi;
(Kanagawa-ken, JP) ; Matsumoto; Shoji; (Chiba-ken,
JP) ; Goto; Koichi; (Kanagawa-ken, JP) |
Correspondence
Address: |
SQUIRE, SANDERS & DEMPSEY L.L.P.
14TH FLOOR
8000 TOWERS CRESCENT
TYSONS CORNER
VA
22182
US
|
Assignee: |
HONDA MOTORS CO., LTD.
|
Family ID: |
34635605 |
Appl. No.: |
10/580826 |
Filed: |
November 25, 2004 |
PCT Filed: |
November 25, 2004 |
PCT NO: |
PCT/JP04/17464 |
371 Date: |
January 3, 2007 |
Current U.S.
Class: |
72/43 |
Current CPC
Class: |
B21K 1/762 20130101;
B21K 27/04 20130101; B21J 3/00 20130101 |
Class at
Publication: |
072/043 |
International
Class: |
B21J 3/00 20060101
B21J003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 26, 2003 |
JP |
2003-395681 |
Nov 28, 2003 |
JP |
2003-395682 |
Claims
1. A forging method including a plurality of press steps for a
formed product, wherein a workpiece heated due to the machining in
an earlier press step(s) prior to a press step of forming the
workpiece undergoes spraying with lubricant more than once; the
spraying with lubricant is conducted when the lubricant sprayed in
a preceding spraying has been dried; and eventually after the
lubricant sprayed in the final spraying has been dried, the press
step of forming the workpiece is conducted.
2. A forging method as defined in claim 1, wherein the workpiece is
a constant-velocity universal joint outer race.
3. A forging method as defined in claim 1, wherein a temperature of
the workpiece ranges from 150 to 250.degree. C. when the workpiece
is sprayed with lubricant.
4. A forging method as defined in claim 1, wherein the lubricant
before a forging procedure is a water-dispersive lubricant
containing a solid lubricant agent, a lubricative and dispersive
adherent agent and a wetting and vaporizing accelerating agent, and
the lubricant during the forging procedure is a solid lubricant
agent.
5. A forging method as defined in claim 1, wherein the formed
product is cup-shaped.
6. A forging method as defined in claim 1, wherein the formed
product is shaft-shaped.
7. A forging apparatus comprising an extruding apparatus, wherein a
workpiece is successively transferred to a series of press stages;
a conveying unit for successively transferring the workpiece is
provided with a nozzle for spraying the workpiece with lubricant;
and the workpiece and the nozzle are located in fixed relative
positions to each other in spraying the workpiece with the
lubricant.
8. A forging apparatus as defined in claim 7, wherein the spraying
with lubricant is conducted intermittently.
9. A forging apparatus as defined in claim 7, wherein there are
more than one of the nozzles from which the lubricant is sprayed in
different directions, and the nozzles spray the lubricant in a
sequential fashion.
10. A forging apparatus as defined in claim 9, wherein after the
lubricant sprayed from the nozzles has been dried, the lubricant is
sprayed from the nozzles.
11. A forging apparatus as defined in claim 7, wherein the
workpiece is a constant-velocity universal joint outer race.
12. A forging apparatus as defined in claim 7, wherein a
temperature of the workpiece ranges from 150 to 250.degree. C. when
the workpiece is sprayed with lubricant.
13. A forging apparatus as defined in claim 7, wherein the
lubricant before a forging procedure is a water-dispersive
lubricant containing a solid lubricant agent, a lubricative and
dispersive adherent agent, and a wetting and vaporizing
accelerating agent, and the lubricant during the forging procedure
is a solid lubricant agent.
14. A forging apparatus as defined in claim 7, wherein the formed
product is cup-shaped.
15. A forging apparatus as defined in claim 7, wherein the formed
product is shaft-shaped.
Description
TECHNICAL FIELD
[0001] The present invention relates to a forging method and
apparatus of forming a material at a temperature below its
transformation point into a cup-shaped product such as a constant
velocity universal joint outer race, and a shaft-shaped
product.
BACKGROUND ART
[0002] Among conventional forging methods for producing cup-shaped
or shaft-shaped mechanical parts, a cold forging method is commonly
used where a material is formed at a temperature below its
transformation point by a die and a punch (e.g., see Patent
Document 1 listed below). In this method, the material undergoing
the forging must be coated with lubricant film, or otherwise, the
forging apparatus is seized. A cylindrical workpiece with an
unwrought surface of approximately 75 in Rockwell hardness Scale B
turns to have a forged surface of 100 or even higher in Rockwell
hardness Scale B after it undergoes the first stage of profiling a
core end, the second stage of preliminarily upsetting, and the
third stage of further upsetting and immediately before the fourth
stage of forming the workpiece into cup by forging.
[0003] There is no way to forge the workpiece as hard as the Scale
B higher than 100, and an "intervening" process should be conducted
between the third and fourth stages, including the steps of
low-temperature annealing to drop the hardness, shot blasting to
eliminating surface oxide film or oxidized scales and bonderizing
to form chemical coating over the surface of the workpiece. Instead
of boderizing, insufflating the workpiece with lubricant may attain
lubricating effects.
[0004] Among the aforementioned lubricating methods, the
bonderizing is unsatisfied to drastically reduce a lubricant film
thickness after a single step of forming, and the procedures with
successive forming steps at a greater forming rate often bring
about disappointing lubricating effects. Moreover, with any means
for insufflating with the lubricant, it is hard to uniformly coat
the workpiece or the die, and if a greater forming rate causes the
lubricant film to be discrete, the formed product may be defective,
and this is also undesirable for work environments.
[0005] In order to cope with these problems, oil bath forming has
been proposed which is a forging method where a material is soaked
in a cavity filled with lubricant in advance (e.g., see Patent
Document 2). In the case of the oil bath forging, however,
lubricant is prone to be confined in space between the material and
the bottom of the cavity during the forging process, depending on
the material shape. In such a situation, it is necessary to make an
opening as a drain for lubricant at the bottom of the cavity of the
die to smoothly drain the confined lubricant into an external tank.
However, providing such a drain is insufficient because after
forming, the formed product may cling to the punch as it is raised
together with the punch in preparation for the next press action,
which may result in the formed product being pressed again by the
punch.
[0006] In order to address the problem, a drain duct leading to the
external tank is made at the bottom of the cavity of the die to let
the lubricant out, and additionally, a check valve is attached to
the course of the drain duct so that it can open the duct when a
pressure of the confined lubricant between the bottom of the cavity
and the material reaches a predetermined level while it can close
the duct when the pressure goes down below the predetermined level
(e.g., see Patent Document 3).
[0007] With the improvement, the lubricant residing in the space
between the bottom of the cavity and the material is returned to
the external tank via the drain duct by virtue of the opening of
the check valve, and after completing the forming, the drain duct
is closed, and the formed product in tight contact with the bottom
of the cavity would not cling to the raised punch. Therefore, the
formed product is left in the cavity.
[0008] Patent Document 1: [0009] Japanese Laid-Open Patent
Publication No. 59-220243
[0010] Patent Document 2: [0011] Japanese Patent Application No.
62-324515
[0012] Patent Document 3: [0013] Japanese Laid-Open Patent
Publication No. 02-187228
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0014] In the above-mentioned extrusion disclosed in Patent
Document 2, the intervening processes are time consuming, and the
lubricating effects attained by the bonderizing may be lost due to
the final extruding. Thus, it is necessary to re-bonderize the
formed product prior to the steps of ioning and coining in the
fifth stage of the forging procedures.
[0015] In the extrusion disclosed in Patent Document 3, the
adhesion of the liquid lubricant is weak, and it is necessary to
repeat the bonderizing again before the ioning and coining steps in
the fifth stage.
[0016] Furthermore, when the fourth stage of the extrusion is
carried out using the oil bath forging where the material is soaked
in the lubricant in the cavity, heat resulted from pressurizing the
workpiece causes the lubricant to ignite, which is a trouble that
must be overcome from the viewpoint of safety management.
[0017] The present invention is made, allowing for disadvantages of
lubricant deterioration and ignition during the conventional
extrusion procedures mentioned above, and accordingly, it is an
object of the present invention to provide a forming method and a
forming apparatus that are, without extending a processing time
compared with the conventional practice, capable of sufficiently
lubricating a formed object and forming at safety without the
lubricant igniting under pressure.
MEANS FOR SOLVING THE PROBLEMS
[0018] A first invention is a forging method including a plurality
of press steps for a formed product. A workpiece heated due to the
machining in an earlier press step(s) prior to a press step of
forming the workpiece undergoes spraying with lubricant more than
once, the spraying with lubricant is conducted when the lubricant
sprayed in a preceding spraying procedure has been dried, and
eventually after the lubricant sprayed in the final spraying
procedure has been dried, the press step of forming the workpiece
is conducted.
[0019] Preferred embodiments of the first invention are
characterized as follows:
[0020] The workpiece is a constant-velocity universal joint outer
race.
[0021] A temperature of the workpiece ranges from 150 to
250.degree. C. when the workpiece is sprayed with lubricant.
[0022] The lubricant before a forging procedure is a
water-dispersive lubricant containing a solid lubricant agent, a
lubricative and dispersive adherent agent, and a wetting and
vaporizing accelerating agent, and the lubricant during the forging
procedure is a solid lubricant agent.
[0023] The formed product is cup-shaped.
[0024] The formed product is shaft-shaped.
[0025] A second invention is a forming apparatus having an
extruding apparatus in which a workpiece is successively
transferred to a series of press stages, a conveying unit
successively transferring the workpiece is provided with a nozzle
for spraying the workpiece with lubricant, and the workpiece and
the nozzle are located in fixed relative positions to each other in
spraying the workpiece with the lubricant.
[0026] Preferred embodiments of the second invention are
characterized as follows:
[0027] The spraying with lubricant is conducted intermittently.
[0028] There are more than one of the nozzles from which the
lubricant is sprayed in different directions, and the nozzles spray
the lubricant in a sequential fashion.
[0029] After the lubricant sprayed from the nozzles has been dried,
the lubricant is sprayed from the nozzles.
[0030] The workpiece is a constant-velocity universal joint outer
race.
[0031] A temperature of the workpiece during the spraying with
lubricant ranges from 150 to 250.degree. C. when the workpiece is
sprayed with lubricant.
[0032] The lubricant before a forging procedure is a
water-dispersive lubricant containing a solid lubricant agent, a
lubricative and dispersive adherent agent, and a wetting and
vaporizing accelerating agent, and the lubricant during the forging
procedure is a solid lubricant agent.
[0033] The formed product is cup-shaped.
[0034] The formed product is shaft-shaped.
EFFECTS OF THE INVENTION
[0035] According to the present invention, without extending a
processing time compared with the conventional practice, a formed
object can be sufficiently lubricated, and the forming is conducted
at safety without the lubricant igniting under pressure.
BEST MODE FOR CARRYING OUT THE INVENTION
[0036] An exemplary forming apparatus according to the present
invention will be detailed in conjunction with the accompanying
drawings.
Configuration
[0037] An extruding apparatus 10 is, as shown in FIG. 1, comprised
of a workpiece supply 12 and a press 14. The workpiece supply 12 is
successively loaded with billet or workpiece W and then retains a
chain of the workpiece W in predetermined alignment position for a
later sequential transfer.
[0038] As can be seen in FIG. 2, the press 14 has first to fourth
press units installed serially equidistantly from one to another:
the first press unit 20 acting as a forward extruder for profiling
a core end, the second press unit 22 as a preliminary upsetting
mechanism, the third press unit 24 as a finishing upsetting
mechanism, and the fourth press unit 26 as a backward extruder for
forming raw material in cup.
[0039] On opposite sides of each of the first to fourth press units
20 to 26, a pair of first and second feed bars 30 and 32 extending
longitudinally are juxtaposed. The first and second feed bars 30
and 32 are provided with eight grip claws 38 through grip
controllers 36. The pairs of the eight grip claws 32 and their
respective associated grip controllers 30 are opposed to their
respective counterpart pairs to pinch the workpiece W in the first
to fourth press units 20 to 26.
[0040] The first and second feed bars 30, 32 are reciprocated by a
feed bar control system (not shown) to conduct up-and-down shuttle
movement over a stroke almost equivalent to a height of the
workpiece W and fore-and-back shuttle movement over a stroke
equivalent to intervals among the first to fourth press units 20 to
26.
[0041] The first and second feed bars 30, 32 have nozzle-retaining
frames 42 and 43 attached and separated from the grip controllers
36 which are dedicated to the third press unit 24, by means of
associated nozzle controllers 40, and the nozzle retaining frames
42 have their respective distal ends provided with first and second
lubricant nozzles N1 and N2, respectively. The first and second
lubricant nozzles N1 and N2 are binary fluid nozzles that use
high-pressure air to spray lubricant. To avoid mutual interference
among the first and second lubricant nozzles N1 and N2, the nozzle
retaining frames 42 and 43, and the feed bars 30 and 32, only in
the presence of the feed bars 30 and 32 in their respective upper
dead spots, the nozzle controllers 40 shift the first and second
lubricant nozzles N1 and N2 to their respective work positions,
namely, the upper dead spots.
Control System
[0042] As will be recognized in FIG. 4, a control system 100 for
the nozzle controllers 40 has pipeline from a compressed air supply
102 connected through a first air decompressing valve 104 to a
succeeding stage where the pipeline is branched in two ways; that
is, one is routed through a first 5-port pilot switch valve 106 to
an air cylinder 108 for the first feed bar 30 while the other is
routed through a third 5-port pilot switch valve 110 to the first
lubricant nozzle N1.
[0043] The pipeline from the compressed air supply 102 is also
connected through a second air decompressing valve 104 to an
additional succeeding stage where the pipeline is branched in two
ways; that is, one is routed through a second 5-port pilot switch
valve 114 to an air cylinder 116 for the second feed bar 32 while
the other is routed through a second 5-port pilot switch valve 120
to the second lubricant nozzle N2.
[0044] The pipeline originating from the compressed air supply 102
is connected through a second air-decompressing valve 122 to spray
air inlets 130 and 132 of the first and second lubricant nozzle N1
and N2.
[0045] A lubricant vessel 140 hermetically containing lubricant L
is provided with a stirrer 142 pneumatically activated by
compressed air from the compressed air supply 102 and is supplied
with compressed air through a third air decompressing valve 144.
The lubricant L held in the lubricant vessel 140 is transferred to
the first and second lubricant nozzles N1 and N2 via pipeline
connected at the bottom of the vessel. The first and second 5-port
pilot switch valves 106 have their respective electromagnetic
valves 150 connected to a control panel 150.
Operation
[0046] The first and second feed bars 30 and 32 fetch the workpiece
W sequentially at a cycle, for example, of 20 spm out of the
workpiece supply 12 and deliver it sequentially to the first to
fourth press units 20 to 26. The first press unit 20 profiles a
core end of a raw material by means of forward extrusion. The
second press unit 22 also conducts forward extrusion to
preliminarily upset the profiled core end. The third press unit 24
carries out the forward extrusion to upset and finish the core
end.
[0047] After completing the upsetting by the third press unit 24,
compressed air is supplied to the air cylinder 108 of the first
nozzle-retaining frame 42 and the air cylinder 116 of the second
nozzle-retaining frame 43. In this way, the air cylinders 108 and
116 respectively raise the first and second nozzle retaining frames
42 and 43, and as depicted in FIG. 4, the first and second
lubricant nozzles N1 and N2 are shifted to their respective work
position to spray lubricant onto the workpiece W. In one embodiment
of spraying the lubricant L, both the first and second lubricant
nozzles N1 and N2 alternately spray the lubricant onto the single
workpiece W, four times from one of the nozzles and totally eight
times from both of the nozzles, for 0.14 seconds each time at an
interval time of 0.01 seconds from one spraying to another.
[0048] Spraying lubricant from more than one nozzles is desirably
conducted on the basis of serial actions to avoid interference of
the sprayed lubricant from one nozzle with the sprayed lubricant
from another.
[0049] During the spraying, the gripped workpiece W and the first
and second lubricant nozzles N1 and N2, which are all fixed to the
first and second feed bars 30 and 32, are naturally in fixed
relative positions to one another, and the spraying manner is
closely analogous to a condition where the lubricant is sprayed
onto a stationary object.
[0050] The workpiece W at the initial stage of the spraying is
heated to approximately 200.degree. C. due to forming heat
developed during the steps of the profiling, preliminary upsetting,
and finishing upsetting that the workpiece W has undergone. Hence,
the lubricant L sprayed is instantaneously vaporized when it
reaches the heated workpiece W. As a consequence, eight-layered
lubricant coat is on the machined surface of the workpiece W, and
thereafter, it undergoes backward extrusion in the fourth press
unit 26 to advantageously attain the cup forming.
[0051] Application of waterborne lubricant in use of plastic
forming is affected by temperature of the lubricant, time required
for spraying the lubricant, and a dilution rate of the lubricant.
For example, Table 1 below shows the results of a spray test where
a pair of nozzles (BIMV4515 available from H. Ikeuchi &
Company, Ltd., Osaka, Japan) were used to alternately spray
lubricant onto the surface of horizontal carbon steel piece of 80
mm in diameter under the following conditions: The nozzles were
diagonally and symmetrically opposed to each other 333 mm above the
carbon steel piece at an angle of 45 degrees to its horizontal
surface, and jetted the lubricant with 0.15 MPa in air pressure and
0.10 MPa in lubricant pressure.
[0052] In Table 1 providing measurements of adhesion of lubricant
film on the surface of the object, 0 denotes lubricant film
uniformly adhered over the entire surface of the object, A means
the lubricant film adhered over an area less than 100% and equal to
or over 50% of the entire surface, and x designates the lubricant
film adhered over an area less than 50% of the entire surface. The
Table 1 also gives measurements of drying property of the sprayed
lubricant where 0 was given if the lubricant dried instanteously, A
if it dried one to two seconds after the spraying, and x if it
dried two or more seconds after the spraying. TABLE-US-00001 TABLE
1 Dilution Temperature Time Number of Rate Drying (.degree. C.)
(sec) Times (times) Adhesion Property 100 0.15 4 10 .smallcircle. x
125 0.15 4 10 .smallcircle. .DELTA. 150 0.15 4 10 .smallcircle.
.smallcircle. 175 0.15 4 10 .smallcircle. .smallcircle. 200 0.15 4
10 .DELTA. .smallcircle. 200 0.15 4 2.5 .smallcircle. .smallcircle.
225 0.15 4 2.5 .smallcircle. .smallcircle. 250 0.15 4 2.5
.smallcircle. .smallcircle. 275 0.15 4 2.5 .DELTA. .smallcircle.
300 0.15 4 2.5 x --
[0053] From the above test results, a conclusion can be drawn that
the desired lubricant temperature during the spraying ranges from
150 to 250.degree. C.
INDUSTRIAL APPLICABILITY
[0054] The present invention is applicable to an extrusion
procedure at a temperature equal to or below the transformation
point of material for cup-shaped products such as a constant
velocity universal joint outer race, and shaft-shaped products, as
well as to a forming procedure for press products required high
rigidity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0055] FIG. 1 is a plan view of an extrusion apparatus according to
an embodiment of the present invention;
[0056] FIG. 2 is a cross sectional view taken along the line II-II
of FIG. 1;
[0057] FIG. 3 is a diagram illustrating progressively transformed
workpiece in a sequence of stages in press units; and
[0058] FIG. 4 is a circuit diagram illustrating a control system
for nozzle controllers.
DESCRIPTIONS OF REFERENCE NUMERALS
[0059] W Workpiece [0060] L Lubricant [0061] N1 First Lubricant
Nozzle [0062] N2 Second Lubricant Nozzle [0063] 10 Extruding
Apparatus [0064] 12 Workpiece Supply [0065] 14 Press [0066] 20
First Press Unit 20 [0067] 22 Second Press Unit [0068] 24 Third
Press Unit [0069] 26 Fourth Press Unit [0070] 30 First Feed Bar
[0071] 32 Second Feed Bar [0072] 36 Controllers [0073] 38 Grip
Claws [0074] 40 Nozzle Controller [0075] 42 First Nozzle Retaining
Frame [0076] 43 Second Nozzle Retaining Frame [0077] 100 Control
System [0078] 102 Compressed Air Supply [0079] 140 Lubricant
Vessel
* * * * *