DE1458976C - Method for producing a hollow body from steel and device for carrying out this method - Google Patents

Description

The invention relates to a method for producing a hollow body made of steel, in which a hollow workpiece enclosed in a divided shape corresponding to the end shape of the hollow body and the heated workpiece by introducing a pressure medium inside it against the Wall of the mold is pressed, whereupon after pressure relief, sufficient cooling and solidification of the material, the finished hollow body is removed from the mold.

The invention also relates to an apparatus for carrying out this method, which has at least two mold jaws movable relative to one another, the inner wall of which has the end shape corresponds to the hollow body to be produced and have the supply and discharge channels.

In known methods of the underlying type, no closed molds are used. Although it is known from German Patent 898 142 to inflate heated steel pipes by a Liquid such as water or steam or nitrogen is injected into the interior of the pipe, The split mold is initially open and is only opened during the blowing process and the resulting Bulges closed. The fact that the driving substance only enters the interior of the When the pipe is injected, the outer surfaces are exposed to a different atmosphere, which is the metallurgical Properties impaired. Initially, only heating takes place during the process and later an expansion due to steam pressure. When the liquid is injected into the cold workpiece there is no gas atmosphere.

Furthermore, it is known from German patent specification 939 030, by pressing by means of liquid or gas pressure in the heat and subsequent cooling of pipes Pre-stresses in hollow bodies bring about. Here, according to German Patent 947 886, the use of Liquid or gas pressures are replaced by a workpiece such as a ball or a mandrel, which are pushed or pulled through the bore of the hollow body.

It is also known from French patent specification 602 690, one on his in the case of the autofrettage The end of the clamped pipe should only be treated with pressure on the inside in sections.

Finally, U.S. Patents 1920,652 and 1928,818 and 2493135 are jigs known for the remuneration of already formed hollow bodies in the form of propeller blades serve. Here, only the remuneration or deterrence is carried out in the clamping device, but not the actual deformation. Also that according to the USA patent specification 2,493,135 in terms of remuneration The inert gas pressure used inside the propeller blade serves only to a uniform contact between the surface of the propeller blade with associated cooling surfaces guarantee.

This currently common manufacturing equipment allows the manufacture of hollow bodies made of steel, in particular a spar with uniform tolerances and uniform metallurgical properties not to. The operating and maintenance costs of the equipment currently used must be in To be considered excessive compared to the results obtained.

The invention is based on the object of solving these problems by means of a method and an apparatus to solve, through which a spar or hollow metallic workpiece is created with very tight tolerances is, so that the dimensions of the spar or the workpiece a uniformity up to one Reach the extent that the vibrations that previously z. B. triggered by the spar, essential can be reduced, and also manufacture with acceptable operating and maintenance costs should be possible and the product has uniform metallurgical properties.

According to the invention, this object is achieved by the method in that both the inner wall the shape and outer wall of the workpiece as well as inside the workpiece An inert atmosphere is generated, whereupon the workpiece is above the austenitizing temperature is pressure deformed, the cooling is accelerated by generating a flow in the inert gas atmosphere and that a known tempering and cooling process is carried out in the mold itself will.

The invention is described in terms of a preferred application with reference to manufacture of a hollow, metallic spar for a helicopter rotary wing described, but It should be noted that the inventive method and the device of the invention can be used to produce other metallic hollow bodies. However, it is especially important in the case of the spars mentioned, because the hollow spar, which supports a helicopter rotary wing is a source of vibration problems in helicopters. Since it is desired that the Rotary blades are balanced with respect to each other to reduce vibration problems, the spars should be as similar as possible in shape and weight.

The invention makes it possible that certain metallurgical properties in the manufacture of the Hollow body can be achieved, resulting in an extraordinary uniformity in dimensions and strength properties.

According to an advantageous embodiment of the invention, the inert atmosphere is by itself known use of nitrogen.

When manufacturing a workpiece from nickel-chromium-molybdenum steel with a nickel content of 1.65 to 2.00 percent by weight, a chromium content of 0.70 to 0.90 percent by weight, a molybdenum content from 0.20 to 0.30 percent by weight, a silicon content of 0.20 to 0.35 percent by weight, a manganese content of 0.65 to 0.85 percent by weight and a carbon content of 0.38 to 0.43 percent by weight, the workpiece is heated to a temperature of 816 ° C according to the invention and held at this temperature for 10 minutes, the pressure medium introduced into the workpiece at 70 atmospheres, maintaining this pressure for 1 minute, the molded workpiece within 20 seconds 260 ° C quenched and at the same time the pressure inside the workpiece on its ambient temperature reduced, whereupon heated to a tempering temperature of 544 ° C and after a holding time of 5 minutes is cooled. The workpiece is preferably heated to 860 ° C. in 30 minutes and reduced to 777 ° C within 10 minutes.

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lowers. It is expedient to reduce the pressure within the FIG. 9 shows a section of a ceramic part with a

Body to be reduced to 7 atm.

to the. Fig. 10 is a side view of part of a ceramic

Advantageously, to deter liquid micro parts to represent an operation,

Nitrogen supplied to the interior of the hollow body S FIG. 11 is a section along line 11-11 in FIG. 10,

and be vaporized in it. Fig. 12 is a section of the spar with the receiving

A steel of the aforementioned composition is used to support the same, and also a

Shown below for brevity as the »4340 inert gas manifold within the spar

Steel «. is,

13 shows a section along line 13-13 in FIG. 12, according to the invention with at least two mold jaws which can be moved relative to one another ,
wall of the final shape of the hollow body to be produced In the drawings, in particular in F i g. 1 corresponds to pers and the supply and discharge channels up to 3, a shape according to the invention is shown, which have, is characterized in that the cavity 15 has a bed 10 with a base plate 11 , on the mold forms a closed heating chamber, which two cooperating metal jackets 12 passages for supplying a gas Heizvorrich- and 14 are pivotably arranged. The jacket 12 lines are assigned and one to a pressure source is provided with an extension 15, which is pivotably connectable for the pressure medium support device bar between two upwardly extending fork for the hollow body to be formed releasably with the 20 legs 16 of the base plate 11 of the bed 10 on form is. a pin 16 a is mounted, which is aligned by

If in such a device thermal bores in the extension 15 and the fork legs

staten for the controllable electric heater 16 extends. The jacket 14 is in the same way

are provided, then these are preferably mounted in a pivotable manner on the bed 10 , specifically by means of

the mold jaws went under spring load to a lug 17 arranged on the jacket

arranged to be movable and with the work two upwardly directed fork legs 18 of the

piece held in contact. Base plate 11 on a pin 18 «, which is

Is the device according to the invention with pressure-oriented bores in the extension 17 and the fork regulators and valves, so it is not 18 interspersed.

advantageous through such an arrangement of these 3 °. The semi-cylindrical jacket 12 has on each pressure regulator and valve that the pressure medium end is a plate 19 and the jacket 14 has the same end, optionally both the interior of the hollow body and plates 20. Each of the end plates 19 has a Mehrauch the heating chamber or a manifold for number of projections 21 (see. Fig. 6), which protrude from these with low pressure or the interior of the hollow plates and to define a position in the body with high pressure and the distribution line with 35 several, cooperating with them Ausnehmun low pressure can be fed. gene 22 engage in the end plates 20. The pre

Next can secure the channels and with a crack 21 and the recess 22

Passage in the support element a vacuum pump ver longitudinal alignment of the jackets 12 and 14 when they are in

be bound. their closed position can be pivoted.

It is preferred that in the case of a support device 40, the jacket 12 also has a recess

which is made hollow and has outlet openings 23 in its uppermost section, into which a

has, the outlet openings for the inert medium engages projection 24, the from the uppermost portion

protrudes tangentially of the jacket 14 in a distributor on the support device. The recess 23 and the

are directed. Projection 24 extend the length of the

If the mold jaws advantageously 45 jacket 12 and 14 and provide a correct pivotable, power-operated metal jacket menpressen the jackets when they are in their closed position are preferably moved in the metal jackets. Furthermore, the cavity of the mold delimiting, the supply and they ensure that a jacket is not moved over the aligned discharge channels or passages for the pressure medium position before the other man-exhibiting ceramic parts replaceably fastened. 5 ° tel has fully reached the aligned position.

The invention will be described below with reference to a As shown in FIGS. 2 and 6, the jackets have

Embodiment described in the drawing 12 and 14 downward protruding portions 139

is shown. In the drawing shows or 140, which are in contact with each other. The sections

F i g. Figure 1 is a side view of a 139 and 140 of the present invention having slotted, interfitting

Shape, 55 surfaces that allow a rotational movement of the shells 12

F i g. Figure 2 is an end view of the form of Figure 2. 1, and 14 allow.

Figure 3 is a plan view of part of the mold. Sections 139 and 140 are arcuate

of Fig. 1, faces shared by the mating faces

Fig. 4 is an enlarged end view are a part removed, and with upwardly projecting Teider form according to Fig. 2, wherein the clamping device len 60 141 and 142 occupies 11 together to a closed position on the base plate act as the sheath 12 and 14 in its ge

Fig. Figure 5 is an end view of part of the mold, in the closed position. This arrangement represents

which the jig is open, ensure that the lower portions of the sheaths 12 and

Fig. 6 is an end view of the mold, similar to Figs. 2, 14 in the closed position in a fixed relationship

in which the mold is open, 65 are held relative to one another.

F i g. 7 shows a section along line 7-7 in FIG. 4, The jacket 12 is actuated by two hydraulic actuators

F i g. 8 shows a section of a ceramic part with a cylinder from its closed position into a part the inlet device for the inert medium, pivoted open position. Each of the two hydraulic

1 458 97ö

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Lischen adjusting cylinder 25 is pivotable on a front The hydraulic adjusting cylinder 49 is pivotable jumped the base plate 27 on the bed 10 between two by means of a pin 54 on a pair of brackets 55 upwardly protruding fork legs 26 of the arranged on the metallic shell 12 base plate 27 on a pin 28 mounted. Anyone attached. Each of the consoles 55, which are attached to the hydraulic actuating cylinder 25, has a piston rod 29, which extends out of the cylinder, and with which the hydraulic and with a portion of the projection 15 by means of electrical servomotor 25 and the fork 30 and a pin 31 extending upwards. kenden fork legs 16 are articulated.
When the hydraulic actuating cylinders 25 pressure- As shown in Fig. 2, the basic means are fed to the piston rod 29 to move plates 27 further to the left of the mold than that, the metallic shell 12 is against basic plates 33 on the right Side, since the base is clockwise (when looking at Fig. 2) plates 27, the clamp elements 39, the hydraulic ones pivoted about the pin 16 α. Adjusting cylinder 49 and the interacting therewith

The metallic jacket 14 is made by means of two parts as well as the jacket 12 and its actuating device.

hydraulic actuating cylinder 32 must support the pin 18 a from 15 direction. The base plates 33 support

its closed position in an open position only the jacket 14 with its actuation

ment and vice versa pivoted. Each of the hydrau- lic direction off.

Lischen adjusting cylinder 32 is pivotable with the bed. In the position of the clamp shown in Fig. 2

10 between two upwardly extending fork elements 39, in which the jacket 12 and 14 in FIG

legs 34 held in their closed position at 20 attached to bed 10

Base plate 33 are arranged on a pin 35 upon actuation of the hydraulic actuating cylinder 49 the

stored. Piston rod 48 in the hydraulic actuating cylinder

Each of the hydraulic actuating cylinders 32 has a 49 retracted. The withdrawal of everyone

Piston rod 36, which from the cylinder in front of and in piston rod 48 causes the cam 45 to the

same can be moved back. The piston pin 46 disengages from the projection 41

The rod 36 can be swiveled between two feed tables. It should be noted that the

Tceln 37, which are attached to the jacket 14, have a curved section 56 on projection 41

a pin 38 mounted. If the hydraulic setting (see Fig. 5), which together with the cam 45

cylinders 32 pressure medium are supplied to the menarbeiten.

To retract the piston rod 36 into the actuating cylinder 32, 30 when the cam 45 moves away from the projection 41

when the jacket 14 is advanced from its closed position, the pin 46 slides along the slots

into its open position by pivoting in the clock 44 in the consoles 43 until the cam 45 on the flange

clockwise (when viewing FIG. 2) engages around pin 47. After the cam 45 on the flange 47

18 a moves. has struck, causes continued withdrawal

The metallic shell 12 and 14 are in their 35 movement of the piston rod 48 that the clamp closed position by a clamp member 39 element 39 pivots about the pins 57, which the held. As in Fig. As shown in FIG. 2, the clamp element 39 engages over the brackets 55 in an articulated manner merelement 39 cause a projection 40 by lugs 58 on the clip elements 39 with a tight fit the metal jacket 12 and a projection 41 to bind. The hydraulic actuating cylinder 49 pivots the metal jacket 14. The clip element 39 also has 40 at the same time around the pins 54, so that the a stop 42, which on one side of the front clamp element 39 jumped into that shown in FIG 40 attacks. in the open position.

The clamp element 39 has on the opposite. After the clamp elements 39 in the in F i g. 5 lying ends two downwardly protruding con-shown open position have been moved, wersolen 43, in which slots 44 are provided. 45 the hydraulic actuating cylinders 25 and 32 be-intermediate the downwardly protruding brackets 43 operates to the jackets 12 and 14 in their open a position is to be pivoted on a pin 46 penetrating the same. Here swivel Cam 45 arranged so that the same with the clamp elements 39 and the hydraulic adjusting pin 46 can move in slot 44. As in Fig. 2 cylinder 49 in the in Fi g. 6 position shown. Which shown is the cam 45 between the projection 5 ° open position of the jacket 12 and 14 is also in 41 of the jacket 14 and a downward-extending F i g. 6 shown. It should be noted that the kenden flange 47 of the clamp element 39 is arranged- detailed description of the hydraulic net. Accordingly, the cam 45 has the effect that the actuating cylinder is only given as an example and that the clamp element 39 the metallic jacket 12 mechanical lever arrangements in place of the hydraulic and 14 can lock in its closed position. 55 connections can be made without more than

The cam 45 is to mean an exchange of equivalent means with a piston rod 48
hydraulic actuating cylinder 49 via an arm 50. Each of the metallic sheaths 12 and 14 have multiple connections. The arm 50 is pivotable with a series of ceramic parts 59 arranged on it. Fork 51 connected to the end of the piston rod. One of the clamp elements 39 is hinged to the adjacent 48 by means of a pin 52. The arm 50 to 60 ceramic part 59 in the jackets 12 and 14 moves in an orderly manner through a slot 53 (see FIGS. 3 and 7). As shown in FIGS. 8 and 9, this is in the clamping element 39 in order to allow a relative movement of the ceramic part 59 by means of a connecting device cam 45 with respect to the clamping element 39, which a screw bolt 61 receives. Attention is drawn to the fact that the nut 60 has to which a plurality of clip members 39 are attached along the 65 tel 12 to the metallic man. The nut 60 is arranged in the ceramic metallic sheaths 12 and 14 of part 59 embedded. On the other end of the screw each clamp element 39 has its own benbolzens 61 nuts 62 in order to have hydraulic actuating cylinders 49. the ceramic part 59 to be connected to the jacket 12

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the. In this way, the ceramic parts can extend radially and in substantially the

59 are easily removed from the metallic jacket, the same distances as the collecting lines 71.

which, if necessary, are listed as examples.

wise if a part should break. It is thereupon The passage connects the chamber 73 with the

pointed out that the ceramic parts 59 in the same 5 passage 63, while the passage 75 the chamber

Manner are connected to the jacket 14 . mer 73 with the passage 65 connects. By-

As shown in FIGS. 8 and 9, close the passages 76, which are substantially in the same ceramic members 59 within the jacket 12 and intervals as the manifolds 71 arranged 14 a cavity between them, wherein a is, connect the passage 63 forms with the through-heating chamber. The special shape of the hollow passage 64. In the same way, the passages create space or the heating chamber depends on the desired 77, which are essentially at the same intervals as the th shape of the part which is arranged in the heating chamber distribution lines 71 to be ordered. Thus, in the formation of the bond between the passage 65 and the passage of a rotary vane spar, it is desirable that one end, passage 66.

namely, the root end of the heating chamber, a circular 15 Each inlet conduit 72 is deformed with a chamber 78 , while the other end is connected, which has a D-shaped cross-section throughout the ceramic. This sub-parts 59 extends and a pair of passages 79 and is clearly shown in Figs. It should, 80 has extending radially therefrom to be understood that the contour of the heating chamber is located in and substantially liesehr the same intervals close tolerances, as this contour gen than 20, such as the distribution pipes 72. The passages form element acts , allows the spar with the 79 to establish a connection from the chamber 78 to the desired close tolerance passage 67, while the passages 80 connect the chamber 78 to the passage 69 . The through

Each of the ceramic parts 59 in the shell 12 has a passage 67 through the passages 81 with a plurality of passages 63 to 70 connected by passage 68 while passage 69 passes over them. Electrical heating coil 137, the passageways 82 are disposed with the passage 70 in Verbinsind in each of the passages 63 to 70, is dung. The passages 81 and 82 are in the to supply heat to the heating chamber. The helical ceramic members 59 of substantially equal 137 are helically wound and spaced as the inlet manifolds 72 at about the same diameter as the passages 30.

63 to 70 on. The passages 63 to 70 serve as the passages 63 to 70 are connected via several common lines for an inlet and an outlet passages or openings 83 to 90 with the heating inlet arrangement for the distribution of an inert flow chamber. The openings 83 to 90 by means of, for example, nitrogen, which are essentially the same spacings as the heating chamber. 35 inlet manifolds 71 and 72. To this

The passages 63 to 70 are at intervals with way the nitrogen or other inert flows

Inlet pipe connections 71 and 72 connected in flowing medium from the source 148 to the interior

Distances along the ceramic parts 59 of the heating chamber via the passages 83 to 90 μm

are arranged and with nitrogen supply source 148 to create an inert atmosphere in the heating chamber.

(see Fig. 14) are in connection. The pipe connections are 4 ° when the heating chamber is heated.

71 and 72 are through passages in the jacket 12 The ceramic parts 59 also have a

connected with flexible hoses 149 and 150 , respectively. release system for the nitrogen gas. As shown in Fig. 9

The hoses 149 and 150 are shown with an inlet, the passages 63 to 70 also form a part

Manifold 151 in connection with that of the exhaust system.

Nitrogen supply source 148 is connected. 45 The exhaust system has exhaust manifolds

As shown in Figure 14, nitrogen flows out of 91 and 92 which are connected to chambers 93 and 94, respectively, of source 148 via a pressure regulator 156 and a. The chambers 93 and 94 extend pressure gauges 157 to the distribution line 151. The stick can then run through the entire ceramic parts 59 in gleisteil either via a pressure regulator 158 in the same way as the chambers 73 and 78 for the inlet or a line bypassing the pressure regulator 158 50 laßsystem, while the manifolds 91 and 92 to flow, which depends on whether an angle valve are arranged at intervals 159th

in the pressure regulator 158 having incidental The exhaust manifolds 91 and 92 are over

Closing line or an angle valve 160 in the main passages in the jacket 12 with the outlet lines

line is open. The nitrogen then flows through 152 and 153 connected. Lines 152 and 153

a manometer 161 and enters the distribution line 55 are connected to an outlet duct 154 (see Fig. 2),

151 , in which a manometer 162 and a through which the nitrogen is released to the atmosphere.

35 atmospheric blow-off safety valve 169 on his leads. It should be noted that everyone

has the extreme end. Ceramic part 59 has the same arrangement. A

The pressure regulator 156 maintains the pressure of the stick valve (not shown) in the outlet cable 154 is

fuel to 140 atmospheres while pressure regulator 158 turned to 60 to close the exhaust system if desired

Pressure reduced to 70 atm. Close the pressure gauge 157.

shows pressures up to 175 atmospheres, the manometer 161 to The chamber 93 has passages 95 and 96 ,

to 70 atmospheres and the pressure gauge 162 a maximum of which extend radially from it and substantially

7 atü. at the same intervals as the distribution lines 91

Each of the distribution lines 71 is arranged with a chamber 65 for connection to the through-

mer 73 , which can be established through the whole of aisles 64 and 66 . The passage 64

Ceramic parts 59 extends and which channel is connected to the passage 63 via the passages 97

and passage pairs 74 and 75 , respectively, which are in connection, while the passage 66 via the

9 10

Passages 98 are connected to passage 63. the heating chamber of the mold by means of support elements 112

The passages 97 and 98 are substantially supported in and 114. The support member 112 supports this

the same distances as the distribution line 91 an- in cross-section circular root end from, while

orderly. the support member 114 has the D-shaped cross section

The chamber 94 has passages 99 and 100, supports the end of the spar having 5,
which extend radially from it and essentially- The support element 112 has a part 115, borrowed at the same intervals as the distribution lines- which are arranged in an internal thread at the root end of the gene 92 and which the chamber 94 spars 111 is screwed into. The part 115 has one with the passages 63 and 70 respectively. The flange 116, which is sealingly connected to a sealing passage 68, engages via passages 101 with the 10 ring 117 in order to create a seal between the passage 97 in connection, while the passage part 115 and the root end of the spar 111 lead to passage 70 via the Passages 102 with through-.

gang 69 is connected. The passages 101 and 102 The part 115 is by welding od. The like. With a

are connected essentially at the same intervals as the tube 119, which is

Distribution lines 92 arranged. 15 tion in part 115 extends so that a passage 120

The passages 63 to 70 are via the outlet into the interior of the spar 111 is created. The passageways 103-110 with the heating chamber in the tube 119 extends through openings in the end tie. The outlet passages 103 to 110 are in the plates 19 and 20 of the jacket jackets 12 and 14, respectively, at the same intervals as the manifold. In this way 20 position, the end plates 19 and 20, the nitrogen or another inert gas, are in close contact with the tube 119. Appropriate seals of the heating chamber via passages 103-110 (not shown) are used to create drainage. However, care should be taken to support the tight fit,
that the outlet manifolds 91 and 92 are only connected to the pipe 119 has an enlarged head 121 that is connected to the atmosphere when a cooler 25 which is screwed into a nut 122. Which the heating chamber is desired. If the Heizkam- nut 122 has a flange 123, which is heated at met, the outlet distribution a flange 124 of an enlarged head 125 lines 91 and 92 are prevented from nitrogen from a pipe 126, whereby the pipe 119 with the heating chamber by closing the valves (not connected to tube 126. Tube 126 is shown facing) in outlet pass 154. 30 one connected to the passage 120-

It should be noted that the ceramic parts have the passage 127. It can thus be seen that

59, which are arranged in the metal jacket 14, a passage to the interior of the spar 111 through

an identical arrangement of inlet and outlet, the support element 112 is created. The pipe 126

passages for the inert gas, preferably stick-is with the source 148 for inert gas, for example

fabric. The flow circuit for cooling 35 nitrogen connected to the interior of the spar 111

the heating chamber is such that the nitrogen that feeds.

through the passages in the ceramic parts 59 The nitrogen flows to passage 127 in the tube enters within the metal shell 12, primarily 126 via a controller 156 (see FIG. 14). The stickover the passages in the ceramic parts 59 fabric can then either via a pressure regulator of the metal jacket 12 flows back. This can be attributed to 40 163 or to a pressure regulator 163 immediately that the hollow part that flows inside, which depends on whether an angle is located within the heating chamber, in contact with valve 164 in the bypass line, which the the inner walls of the ceramic parts 59 contain pressed pressure regulator 163, or an angle valve 165 before cooling is performed. is open in the main line. The nitrogen flows

It should be understood that if any 45 then through a connection to a vacuum pump

the passages 63 to 70 of the connecting passages 155 and via a pressure gauge 166 to the passage

76, 77, 81, 82, 97, 98, 101 and 102 the inlet passage- 127 of the tube 126.

passages 83 to 90 or the outlet passages 103 to The pressure regulator 163 keeps the pressure at 70 atü,

110 should clog, the inlet, outlet and manometer 166 shows a maximum of one pressure

Systems adjust to a continuous feed 5 ° of 70 atü. It should be noted that the

of nitrogen to the heating chamber without the vacuum pump 155 also connected to the line

To interrupt operation essentially. which supplies nitrogen to distributor line 151

As mentioned before, the inner walls are the lead.

Ceramic parts 59 are designed in such a way that they interact with the support element 114 has a tube 128 with a spar 111 (see FIG. 12), which has a passage 129. The tube 128 has a rather the main part of a helicopter rotary wing blade first section 130 with a circular circumference and tes. The root end of the spar has a second section 131 with an oval circumferential cross-section, while the other catches, as is clearly shown in FIG. The end has a D-shaped cross section. It should be circular section 130 extends through which it will be understood that any type of hollow body can be produced in the 60 openings in the end plates 19 and 20 of the metal mold according to the invention, if there is casing 12 and 14. If the casings 12 and 14 in if it is desired to heat treat the body in its closed position, fit the ends to molding or tempering in plates 19 and 20 close to portion 130 of the various process steps. The tube 128 together. Appropriate gaskets (not contouring the inner walls of the ceramic parts 59, 65 must be shown) are used to create the course, modified to support the particular shape of the tight fit.
To form hollow body. The tube 128 is attached to the spar by a plate 132

As shown in FIG. 12, the spar 111 is attached within 111. The plate 132 is on the oval ab-

11 12

cut 131 of the pipe 128 and at a waste end 137 a in the jackets. Thus, the heat can

section of the spar 111 welded on. Around that of the coils 137 in the passages 63 to 70

Removing the support element 114 from the spar 111 is regulated in a suitable manner by a console

it is necessary to be the sloping end portion of the spar.

111 cut off. This falling end section, wel- 5 The control of the heating coils 137 depends on the

rather remains attached to the plate 132 , the temperature in the heating chamber can then decrease. So it is

however, with the falling end portion of another required several thermostats 138 or the like. To

Holmes will be connected, which in the heating use to be in different sections of the

chamber of the furnace is to be used. To maintain the temperature on this heating chamber. The Ther-

In the same way, the support element 114 can operate several times io mostats 138 are in the passages 135 and 136

used before it must be discarded. (see Figs. 8 and 9) spaced apart

The support element 112 can of course be rearranged again and again. The thermostat 138, which is spring loaded

be used as there are screw connections to allow them to come out of passages 135 and 136

the spar 111 has. removed and in contact with the handle 111

The passage 129 in the tube 128 provides a retainer when inserted into the passage from the inside of the spar to the outside passages 135 and 136 extend the shape. The circular section 130 of the passages 135 and 136 through suitable pipe 128 is connected to the atmosphere via a vent 167 (see Fig. 14) openings in the metallic jackets 12 and 14 , with the vent to the console where the temperature A valve 168 is arranged in the heating 167 , which is displayed and recorded in the chamber.
The flow regulates the flow of nitrogen, which enters the interior of the spar 111 through the support element 112 , with regard to the heat treatment, the shaping of the spar. The trigger 167 and spar crank 111 when off also includes a relief valve 170 . It will be made of 4340 steel. Attention is drawn to the fact that the flow 25 is pointed out that the shape of the invention flow through the interior of the spar 111, if desired for use for any hollow part, is also suitable in the opposite direction, which can be made of any material. can be made on which it is desired,

In using liquid nitrogen as any or all of the process steps of the thermal fluids that pass through the interior of the spar 30 treatment, molding, and tempering 111 , it is desirable to be as large as possible.

Liehe to achieve distribution of the nitrogen, if the beam 111 is first connected to the dandy for cooling purposes inside the Holmes 111 comparable element 112 by the member 115 is in the turns. Accordingly, a distributor 143 in the tie bar is screwed by 111 and the plate 132 disposed inside of the spar 111 and has an 35 of the supporting element 114 with the spar welded cylindrical member 114, which is a plurality. When the spar 111 has been attached to the support members by openings 145 to the inert flow 112 and 114 , the metallic agent will be distributed. Jacket 12 and 14 by the hydraulic actuating

If desired, the openings 145 in cylinders 25 and 32 can be in their closed position

moved at an angle to the radius of the zylin- 40.

-cylindrical part 144 to be directed to a spinal The clamp elements 39 are then to be produced by the effect and the cooling effect of the nitrogen hydraulic actuating cylinder 49 pivoted to increase the fabric. It should be understood that the metallic jacket 12 and 14 in their closed nitrogen position is in the gaseous state of holding position. During the movement of the clamp when it flows through the openings 145. 45 elements 39 in the position in which they hold the metal

The distributor 143 is preferably supported on the support elements 12 and 14 in their closed elements 112 and 114 , so that only holding the slide position, the stop section 42 engages the projection 40 of the metallic jacket 12 on metrically opposite stiffeners 146 and 147 . are required to prevent the part from further movement of the piston rod 48 of the 144 from flexing or becoming arcuate. When 50 hydraulic servo cylinder 49 causes the distributor 143 is not off from the support member 114 cam supports 45 with the downwardly extending, suitable supporting devices have) flange 47 of the clamp element 39 and the caution shown at the end of the portion 144 near jump 41 of the metallic jacket 14 coming together at the end of the spar 111 closest to the supporting effect, the jackets 12 and 14 can be used in their closed element 114. 55 to lock this position.

At each end, the ceramic parts 59 have grooved surfaces which connect the passages 63 to 70 with metallic jackets 12 and 14 that connect the heating to the outside of the mold. A passen- chamber between the ceramic parts 59. The part of the ceramic 134 may in each grooved ends of the heating chamber are surface are inserted through the end plates, as shown in FIGS. 10 and 11, 60 19 and 20 of the metallic coats is contraindicated displays 12 and 14 . The part 134 has passages 137 ' for closed. The end plates 19 and 20 engage the support elements 112 and 114 close to electrical connections to the heating coils 137 .
in passages 63 to 70 . Inert flow The openings 83 to 90 and 103 to 110 are connected with the medium but cannot come from the passages of the vacuum pump 155 (see Fig. 14), 63 to 70 to the outside of the ceramic parts 59 65 which the normal atmosphere from the heating chamber escape. The electrical connections go away. The angle valves 159 and 160 and then from the ceramic parts 134 to the external vent valves (not shown) in the vent 154 are closed on the side of the jacket 12 and 14 by suitable openings during this venting process.

Similarly, the interior of the spar 111 is connected to the vacuum pump 155 via the passages in the support member 112 to remove the normal atmosphere from the spar 111. The angle valves 164 and 165 and the trigger valve 168 are closed during this venting process. In this way, the air surrounding the inside and outside of the spar 111 is removed.

An inert flowing medium, for example nitrogen, is then inserted through the inlet passages of the openings 83 to 90 into the heating chamber. The nitrogen is pushed through the various passages with a regulated pressure of 7 atmospheres. The nitrogen flows continuously through the inlet passageways 83 to 90 in order to maintain an inert atmosphere in the heating chamber. The continuous flow is intended to replace any losses in the heating chamber due to leakage. The outlet manifolds 91 and 92 are of course adjusted at this point so that nitrogen does not leak from the heating chamber by keeping the valves (not shown) in the vent 154 closed. The nitrogen creates a non-oxidizing atmosphere in order to reduce the formation of scale and / or discoloration on the surface of the spar 111 to a minimum. ^ This scale and discoloration occur in a normal atmosphere at high temperatures to which the spar 111 is exposed.

After the spar 111 is surrounded by an atmosphere of nitrogen or another inert flowing medium, the electrical heating elements or coils 137 are supplied with sufficient voltage to bring the heating chamber to a temperature which the temperature of the spar 111 above the critical temperature of the Material increased, which is 760 ° C for 4340 steel according to the example.

The temperature of the heating chamber is increased so far in 30 minutes that the temperature of the spar rises to 816 ° C. During the next 10 minutes this peak temperature will rise to 777 ° C reduced. In this time span of 10 minutes, the steel changes completely to austenitic Structure so that the material is easily deformable.

The temperature of the heating chamber is measured by thermostat 138 and recorded on the console. The console controls are adjusted to maintain the required voltage for the electrical heating elements 137 so that the temperature in the spar 111 does not drop below 777 ° C during the 10 minute period.

After the temperature of the spar has been maintained higher than 777 ° C for about 9 minutes, an inert flowing medium, for example nitrogen, is introduced into the interior of the spar 111 at a very high pressure to create an internal pressure of 70 atmospheres inside the spar 111 maintain. This is accomplished by opening valve 164 and closing valve 165 , with regulator 163 maintaining the desired pressure. The passage 129 in the support member 114 is of course not connected to the atmosphere via the vent 167 since the valve 163 is closed. In this way, the nitrogen can build up a sufficient pressure within the spar 11 , whereby it is

Gears 127 and 120 in the support element 112 flows into the spar.

This high internal pressure expands the spar 111 against the inner walls of the ceramic parts 29 in order to deform the spar 111 to the desired dimensions. In this way, the special shape of the contours of the inner walls of the ceramic parts 59 makes it possible to produce a spar 11 within very narrow tolerances. The height

ίο A pressure of 70 atmospheres is maintained inside the spar 111 for 1 minute in order to end the deformation process.

When the deformation process has ended, the heating elements 137 are switched off. Simultaneously, the interior of the spar 111 is vented through the passage 129 in the support member 114 by opening the trigger valve 168 and the outlet manifolds 91 and 92 are vented to atmosphere by opening the valves (not shown).

zo opened in vent 154 .

The nitrogen is forced through the inlet passages 83 to 90 into the heating chamber and then through the exhaust passages 103 to 110 at a sufficient rate and in sufficient amount to rapidly cool the spar 111th It should be noted that some nitrogen from the intake manifolds 71 and 72 in the Auslaßverteilerleitungen 91 and 92 can flow up to 70 via the common passages 73rd This is not a problem, however, since there is still sufficient flow through the inlet openings 83 to 90 into the heating chamber and out of the outlet openings 103 to 110 to create sufficient nitrogen flow past the spar 111 and cool it down quickly. The nitrogen is also forced through the interior of the spar 111 to simultaneously assist in the rapid cooling of the spar.

It is desirable to convert the austenitic structure of the 4340 steel to a martensitic structure without significantly forming undesirable microstructures such as ferrite or pearlite. Crystalline structures occur within the aluminum material, which result from the fact that the quenching did not take place sufficiently quickly. When 4340 steel is to be transformed from an austenitic into a martensitic state, accordingly, it is necessary, that is cooled to 26O ⁰ C within 20 seconds. This rapid quenching of the spar prevents the formation of undesirable microstructures. By converting the austenitic state into the martensitic state, the material retains the desired metallurgical properties, such as hardness and strength. The thermostats 138 indicate on the console that the temperature within the heating chamber has decreased enough to achieve the desired result.

Once the temperature in the heating chamber has reached the desired level, the rapid circulation of nitrogen is stopped by closing the valves (not shown) in the hoods 154 so that flow through the outlet manifolds 91 and 92 is prevented. Likewise, the flow of nitrogen through passage 129 in support member 114 is interrupted by closing outlet valve 168 . It

however, nitrogen is still being introduced into the heating chamber through inlet ports 83 to 90, to maintain the inert atmosphere in it just as it was the case as the spar 111 was heated to a temperature which was above the critical temperature. That way will the nitrogen on one. Pressure of 7 atü is maintained in the heating chamber, with a continuous Flow takes place to compensate for leakage, etc.

The heating elements 137 are then turned on again to heat the spar 111 to 544 ° C. This takes place for 30 minutes, the temperature being recorded on the console by means of the thermostat 38 will. The appropriate voltage is applied to the heating elements 137 to maintain the temperature for 5 minutes to / hold at 544 ° C for a long time and to leave the spar 111 on. The specific tempering temperature depends depending on the material, of course. Tempering is used to increase the toughness of the spar 111, because the rapid quenching from the martensitic state creates a hard but brittle structure.

Thereafter, the spar 111 is cooled as quickly as practically possible. First up are the heating elements 137 switched off in order to prevent further heat supply to the heating chamber. Then can the spar 111 can be cooled as desired, with the forced circulation of nitrogen, if desired, can be done in the same way as when cooling after the heat treatment. This inevitable However, circulation is not required after starting because of the length of the cooling period to achieve the structural properties of the material after the tempering process is insignificant. Forced circulation cooling, of course, allows more parts to be produced in the same time which makes the forced circulation during cooling desirable. The inevitable circulation of the nitrogen can be used not only around the exterior of the spar 111, but it is also desirable to maintain it through the interior of the spar 111. Obviously diminished the passage of nitrogen through the interior of the spar 111 is necessary for cooling Time.

When the thermostats 138 indicate that the heating chamber temperature is at a level at which the spar temperature is below 122 ° C, the nitrogen supply from the source 148 is turned off by valves 159 and 164 are closed. Then the mold is opened by first pressing the hydraulic actuating cylinders 49 are actuated to move the clamping elements 39 out of the locking position with the metallic jackets 12 and 14 in their closed position to move. Thereafter, the hydraulic actuating cylinders 25 and 32 operated to move the jackets 12 and 14 to their open position, as shown in FIG. 6 is shown.

The support element 112 is then screwed out of the spar 111, and the support element 114 is separated from the spar 111 by cutting off a waste end of the spar 111 as mentioned above. The spar 111 is then free to be removed from the mold. Another part can then be put into the mold inserted and the procedure repeated.

It should be obvious that the mold is only used for heat treatment and deformation of a material can be used even if the material does not require tempering. In In this case, the material is first heated to a high temperature at which it becomes deformable is so that the various materials or alloys would be in solution. After that an internal pressure is exerted on the hollow body so that it expands into contact with the ceramic walls will. It should be noted that the support elements 112 and 114 with the spar 111 any other hollow body cooperate in such a way that a sealed interior is created, so that the desired internal pressure can be achieved. Even if a material does not require tempering makes, it is of course desirable that it is at its deformation temperature in a non-oxidizing Atmosphere is heated so that no scale formation, etc. during the heating process occurs.

While each of the shells 12 and 14 is shown equipped with three ceramic pieces 59, can of course, any number of ceramic parts 59 can be provided, which of the Length of the hollow body depends, which is to be made in the mold. Each of the ceramic parts 59 serves several purposes. Each part 59 contains the exact contour of the spar 111 in the raised Temperature and passages for the inert fluid, encloses heating elements 137 and acts as an isolator.

An advantage of the invention is that only a single device is required to achieve the Heat treatment of the material, deform it into the desired shape and the material in a regulated Deter atmosphere. Another advantage of the invention is that the manufacturing cost of the spar, which is the main support of the Kubicopter rotary wing forms, at the same time a more uniform product is achieved. Another advantage of the invention it can be seen that the vibrations of the helicopter, which spars according to the invention as Has part of the Drehfüigeiblätter, be reduced, which is due to the extreme dimensional accuracy as a result of the tighter tolerance that the Use of the form of the invention can be achieved.

Claims (12)

P aten claims: 1. A method for producing a hollow body made of steel, in which a hollow workpiece in a divided shape formed according to the end shape of the hollow body included and the heated workpiece by introducing a pressure medium into its interior against the wall the mold is pressed, whereupon after pressure relief, sufficient cooling and Solidification of the material, the finished hollow body is removed from the mold, characterized in that both between the inner wall the shape and outer wall of the workpiece as well as inside the workpiece an inert atmosphere is generated, whereupon the Workpiece is compression deformed above the austenitizing temperature, by generating a Flow in the inert gas atmosphere accelerates the cooling and that a known per se Tempering and cooling process is carried out in the mold itself. 109 521/23 2. The method according to claim 1, characterized in that the inert atmosphere through known per se use of nitrogen is generated. 3. The method according to claim 1 or 2 for the production of a workpiece made of nickel-chromium-molybdenum steel with a nickel content of 1.65 to 2.00 percent by weight, a chromium content of 0.70 to 0.90 percent by weight, a Molybdenum content from 0.20 to 0.30 percent by weight, a silicon content from 0.20 to 0.35 percent by weight, a manganese content of 0.65 to 0.85 percent by weight and a carbon content from 0.38 to 0.43 percent by weight, characterized in that the workpiece on The pressure medium is heated to a temperature of 816 ° C and kept at this temperature for 10 minutes introduced into the workpiece at 70 atmospheres, maintain this pressure for 1 minute Shaped workpiece quenched to 260 ° C within 20 seconds and at the same time the Pressure within the workpiece is reduced to its ambient temperature, whereupon heated to a tempering temperature of 544 ° C, cooled after a holding time of 5 minutes ,will. 4. The method according to claim 3, characterized in that the workpiece in 30 minutes heated to 860 ° C and lowered to 777 ° C within 10 minutes. 5. The method according to claim 3 or 4, characterized in that the pressure within the Body is reduced to 7 atmospheres in deterrence. 6. The method according to any one of claims 1 to 5, characterized in that for deterrence liquid nitrogen is supplied to the interior of the hollow body and evaporated therein. 7. Device for performing the method according to one of claims 1 to 6, with at least two mold jaws movable relative to one another, the inner wall of which corresponds to the final shape of the hollow body to be produced and the supply and discharge channels, characterized in that the cavity of the mold (12, 14, 19, 20, 59) forms a closed heating chamber, passages (63 to 70) for supplying a gas are assigned to heating devices (137) and a support device (112, 114) that can be connected to a pressure source (148) for the pressure medium for the forming hollow body (111) is releasably connectable to the mold. 8. Apparatus according to claim 7, in which thermostats are provided for the controllable electrical heating devices, characterized in that the thermostats (138) in passages (135, 136) of the mold jaws are arranged movable under spring load and with the workpiece (111) in Touch to be held. 9. Apparatus according to claim 7 or 8 with pressure regulators and valves, characterized by such an arrangement of the same that the pressure medium either the interior of the hollow body (111) and the heating chamber or a manifold (151) for this with low pressure or the interior the hollow body (111) can be supplied with high pressure and the distribution line (151) with low pressure. 10. Apparatus according to claim 7, 8 or 9, characterized in that a vacuum pump (155) with the channels (83 to 90, 103 to 110) and with a passage (120) in a support element (112) can be connected. 11. Device according to one of claims 7 to 10, in which the support device is hollow and has outlet openings, characterized in that the outlet openings (145) for the inert medium in a distributor (143) on the support device (112, 114) tangentially are directed. 12. Device according to one of claims 7 to 11, the mold jaws having pivotably arranged, power-operated metal jackets, characterized in that in the metal jackets (12, 14, 19, 20) delimiting the cavity of the mold, the supply and discharge channels or passages (63 to 110) for the pressure medium having ceramic parts (59) are exchangeably attached. For this purpose 3 sheets of drawings