DE102008012550A1 - Thermally treating a tubular body of a delivery pipe, comprises heating and hardening an inner surface of the body, subjecting an outer surface of the body with a coolant, and adjusting the cross-section of the body by a molding tool - Google Patents

Abstract

The method comprises heating and hardening an inner surface (2) of a tubular body (1), subjecting an outer surface (7) of the tubular body with a coolant, and adjusting the cross-section of the tubular body by a molding tool (9) arranged interiorly in the tubular body during thermal treatment. The tubular body is pressed by applying a force on the inner surface by the molding tool in a round form, is rotatably moved around its longitudinal axis and in longitudinal direction (L) relative to the molding tool during thermal treatment and is moved to a heating device arranged in the tubular body. The method comprises heating and hardening an inner surface (2) of a tubular body (1), subjecting an outer surface (7) of the tubular body with a coolant, and adjusting the cross-section of the tubular body by a molding tool (9) arranged interiorly in the tubular body during thermal treatment. The tubular body is pressed by applying a force on the inner surface by the molding tool in a round form, is rotatably moved around its longitudinal axis and in longitudinal direction (L) relative to the molding tool during the thermal treatment and is moved to a heating device arranged in the tubular body. The molding tool is rotatably moved together with the tubular body. The inner surface of the tubular body is heated by an inductor (3) and is subjected with the coolant after the heating. Independent claims are included for: (1) a method for manufacturing a delivery pipe; and (2) a device for thermally treating a tubular body of a delivery pipe.

Description

The The invention relates to a method and a device for heat treatment a tubular body for a delivery pipe and a method of manufacturing a production pipe.

Far widespread is the use of delivery pipes in the pipe string the concrete distributor masts of truck-mounted concrete pumps and the like Applications in hydraulic or pneumatic transport of solids by means of pipelines.

The requirements for such delivery pipes are complex. On the inside, the delivery pipes should have the highest possible hardness to oppose the usually very abrasive solids high wear resistance, whereas the outside of the delivery pipes should be shock and pressure resistant with low risk of breakage and cracking. In addition, a long service life of the delivery pipes is aimed at the simplest possible construction. By the DE 198 09 529 C2 includes a conveyor pipe for the transport of solids to the prior art. The production pipe has a single-layer hardened tubular body made of a steel material. In order to assemble the delivery pipes to form a pipe string, the pipe bodies are equipped at each pipe end with coupling collars.

An apparatus and method for quench hardening of pipes using a pipe heating inductor is known from US 5,156,055 DE 23 49 913 A1 known. Here, the tube experiences within a quenching device by an externally mounted inductor a continuous heating to hardening temperature and a deterrence from outside and inside by means of quenching.

The from the US-A-2,556,243 Known proposal describes the hardening of the outer and inner surface of a tubular body. For this purpose, an inner and an outer inductor are provided, each with associated Abschreckbrause.

The are tubular body produced by the known methods for use as conveying pipes for solids transport not or only conditionally suitable, but at least in need of improvement, because they are due to their hardness in the field the outer wall to breakage and cracking in practical operation tend.

Especially in thin-walled tubular bodies with a wall thickness of 5 mm or less, the hardening of the inner forms Surface of the pipe body using a Heating device in the form of an inductor as difficult because a controller the hardening process over the wall thickness not or only conditionally possible. The wall of the pipe body is completely annealed and due to the hardened by subsequent cooling. In practice, however, it would be desirable, in particular for reasons of weight, high-performance delivery pipes or tubular body for delivery pipes available to provide with low wall thickness and a precise trained hardening zone on the inner surface of the tubular body and a tough material structure on the outside.

Of the Invention is therefore based on the prior art, the task based, a method and apparatus for heat treatment of a Show tubular body of a conveyor pipe, with which is a precise formation of a hardening zone on the inner surface of the tubular body, in particular in thin-walled tubular bodies, is possible and further a method of manufacturing a production pipe to show from such a tubular body.

The inventive method for heat treatment a tubular body for a delivery pipe characterized in claim 1.

According to the invention the cross section of the tubular body during the heat treatment set by a arranged in the tubular body molding tool.

With the method according to the invention, even with thin-walled tubular bodies with a wall thickness of 5 mm or less, a very precise hardening depth can be achieved on the inner surface of the tubular body. This is achieved by the shape determination of the tubular body in the heating zone during the heat treatment via the mold and the qualified cooling, in which the heat removal on the outside is so high that the outer boundary layer is not above the transformation temperature, ie the A _C3 transformation point of the material , is heated. In this way, in the outer surface layer, the transformation of ferrite into austenite is prevented, so that the layer is not cured.

advantageous Further developments of the method according to the invention are the subject of dependent claims 2 to 9th

Of the Pipe body is by force on the inner surface pressed around by the mold. Setting the Cross-section of the tubular body contributes significantly for a precise hardening process.

Manufacturing technology, the pipe body inevitably on a certain ovality. This ovality caused by inductive heating by an inductor arranged inside the tubular body Stray fields of the magnetic field or an uneven heating of the tubular body and thus leads to an uneven and insufficient curing process. According to the invention, the tube is pressed round during the curing process and / or held in the round shape, so that a precise hardening of the inner surface of the tubular body is possible.

through an outer ring shower is the tubular body at the heat treatment in the area of the heat treatment zone cooled outside, and so strong that, as before described in an outer surface layer of Tube body does not exceed the transformation temperatures become. The setting of the cooling capacity can be over a temperature control of the coolant and / or the order quantity take place on coolant.

Preferably the tubular body consists of a highly wear-resistant Steel material, especially steel grade C60, with corresponding high carbon content. The heating of the tubular body from the inside is preferably inductive. Accordingly comes as Heating device for heat treatment an inductor for use. By means of the inductor becomes the inner surface of the tubular body and the wall area to be hardened to a temperature above the complete ferrite dissolution heated and the steel material austenitized. Subsequently the tube body is cooled quickly. hereby occurs a transformation of austenite into martensite. Through this Structural change becomes the inner surface hardened the tubular body. The cooling can over the coolant order on the outside take place of the tubular body. Furthermore, the inductor a downstream arranged in the tubular body Abschreckbrause be.

at the heat treatment becomes relative to the tubular body to the mold and also arranged in the tubular body Heating device moves. Preferably, the tubular body during the heat treatment is rotated about its longitudinal axis. hereby is a uniform heating of the Inner layer of the tube body during the heat treatment ensured. Furthermore, the tube body becomes longitudinal, So in its longitudinal axis, relative to the mold and moved to the heater. Also, the mold is rotating moves, preferably rotates the mold together with the tubular body, while at the same time the tubular body in the longitudinal direction is advanced relative to the mold and to the heater.

Around to complete the tube body to a conveyor tube, this end is provided with flanges (claim 10). By means of the flanges, the delivery pipes can be coupled together a pipe string. Preferably, the flanges adhered to the ends of the tubular body (Claim 11). As a result, adverse microstructural changes on the tubular body as a result of thermal joining operations be avoided.

Of the objective part of the task is by a device for heat treatment of a tubular body according to Characteristics of claim 12 solved.

The Device comprises at least one mold, which in the tubular body is arranged. By means of the molding tool is the cross section of the Tubular body from the inside during the heat treatment adjustable in the heated area of the tubular body.

By the inner mold can be the cross section of the tubular body set and pressed or held around. These Action ensures a precise Hardening process with a very precise hardening depth and a defined, hardened inner surface layer, whereas an outer surface layer is its ductile one Material properties reserves.

Further Specifications of the device according to the invention are characterized in the dependent claims 12 to 21.

The Forming tool has active surfaces which the inner surface Contact the tubular body and by applying force on the inner surface of the tubular body the Define and adjust the cross-section of the pipe body.

By the inner mold becomes the tube during the curing process pressed around and / or held in the round shape, so that a precise hardening of the inner surface the tubular body is possible.

at The heat treatment becomes the tubular body, as already explained above, moved relative to the mold. Preferably, the device has a rotary drive for rotation of the tubular body. Furthermore, a feed unit for longitudinal displacement of the tubular body relative to the mold and provided for arranged in the tubular body heater.

When Heating preferably comes an induction coil or a Inductor used, opposite to the inner surface the tubular body spaced over sliding blocks and is positioned.

The mold is rotatably mounted within the tubular body to a holder. In front Preferably, the mold is coupled to the arranged in the tubular body heater, so that for the mold and the heater a common bracket for positional positioning can be used within the tubular body. On the holder, the mold is rotatably mounted via a ball or roller bearings.

at a particularly advantageous embodiment for practice of the mold, this has a circular mandrel head, which at least on one end face, expediently on both faces, has an inclined surface. The inclined surface acts as a lead-in, over which easily retracted the mold into the tube body or can be pressed. The insertion be relieved the insertion process and total displacement of the tubular body relative to the mold. About trained on the Dornkopf Active surfaces is the cross section of the tubular body set.

in principle already enough, an inner mold for setting the cross section of the tubular body. This can, in the feed direction of Seen tubular body, in front of or behind the heater be positioned. In the context of the invention can also be both before be arranged as well as behind the heater a mold.

To the Hardening of the inner surface of the tubular body can the outside cooling over an external shower suffice. Furthermore, it is possible the heater in the tubular body an internal cooling in the form of an indoor shower to assign. This is the heater downstream, so after heating the inner surface or an inner layer of the tubular body on or over the transformation temperature of the steel material is a quick cooling takes place, through which sets the microstructure transformation and the hardening of the inner surface occurs.

Of the Outer diameter of the molds is on the nominal cross section tuned a tubular body. Due to the cross section of the Mold is the tube body from the inside into the round Form brought and compensated for possible ovalities of the tubular body. It is possible that a mold in the outer diameter is made changeable, so that the outer diameter of the mold or the mandrel head to different diameters a tubular body, ie different pipe sizes, can be adjusted. These are the outer ones Active surfaces of the mold or the mandrel head in their designed radial position movable.

The The invention is based on an embodiment described in more detail. Show it:

1 to 6 in each case a longitudinal section through an embodiment of a device according to the invention for the heat treatment of a tubular body;

7 a cross section through a tubular body and

8th technically schematized a conveyor pipe with a pipe body according to the invention in a longitudinal section.

In the 1 to 6 is in each case a device A, B, C, D, E, F for the heat treatment of a tubular body 1 for a conveyor pipe called. The pipe body 1 is single-layered and consists of a highly wear-resistant steel material, in particular steel grade C60. The pipe body 1 has a wall thickness s (see also 7 ) of less than 5 mm, in particular, the tubular body 1 a wall thickness s of 2-3 mm.

The device A comprises a receptacle, not shown here, in which the tubular body 1 is held at the heat treatment. For heating the inner surface 2 of the tubular body 1 The device A comprises a heating device in the form of an inductor 3 , The inductor 3 is end to a bracket 4 attached. The power supply is with 5 characterized. For cooling the inductor 3 becomes the power supply 5 inside of coolant KM flows through.

The inductor 3 is on a drawbar 6 held stationary and can over the drawbar 6 in the tube body 1 be positioned.

For cooling the outer surface 7 of the tubular body 1 is an outdoor ring shower 8th intended.

The device A further comprises a molding tool 9 which is inside the tubular body 1 arranged and on the drawbar 6 with the interposition of a ball bearing 10 is rotatably mounted. The mold 9 has a circular spike head 11 with an effective surface 12 on the outer circumference, which is the inner surface 2 of the tubular body 1 contacted. On the outer circumference, the mandrel head 11 on both ends 13 . 14 an oblique surface 15 respectively. 16 on. The inclined surfaces 15 . 16 act as an insertion bevel or facilitate the longitudinal movement of the tubular body 1 relative to the mold 9 ,

To a pipe body 1 To cure, this is in the device A in the longitudinal direction over the mold 9 and the inductor 3 pushed. Through the mold 9 becomes the tubular body 1 set from inside to the nominal cross-section, round pressed and kept in shape during the heat treatment. The feed or longitudinal direction is indicated by the arrow L. The mold 9 is in the longitudinal or feed direction L in front of the inductor 3 arranged. By means of the inductor 3 becomes the tubular body 1 then heated internally to hardening temperature above the A _C3 point and then rapidly cooled by the externally applied coolant KM. As a result, an inner layer becomes 17 hardened (see also 7 ). At the same time, the outer surface becomes 7 of the tubular body 1 through the coolant application via the external ring shower 8th so much chilled that on the outer surface 7 of the tubular body 1 the conversion or hardening temperature is not exceeded due to the large heat dissipation. This retains the outer surface 7 or an outer layer 18 the Wall 19 of the tubular body 1 Their ductile material properties and remains impact and pressure resistant.

In the heat treatment, the tube body 1 through the mold 9 kept precisely round. As a result, the inductor 3 all around a constant distance to the inner surface 2 of the tubular body 1 , As a result, stray fields can be avoided, but at least reduced so much that they do not adversely affect the heating and curing process.

In the heat treatment, the tube body 1 , as mentioned, in the longitudinal direction L relative to the inductor 3 and the mold 9 emotional. The feed takes place via a feed unit 20 , from here a counter bearing 21 for the tubular body 1 is shown. At the same time, the pipe body 1 by means of a rotary drive R, not shown, relative to the inductor 3 rotates about its longitudinal axis LA moves, as indicated by the arrow R.

With the tube body 1 rotates the mold 9 or the mandrel head 11 of the mold 9 whereas the inductor 3 fixed.

The devices B to F according to the 2 to 6 correspond to the basic structure and in the course of the heat treatment and the hardening process of the previously 1 explained device A. Corresponding components or component components are therefore in the 1 to 6 provided with the same reference numerals.

The Devices A to F differ in the positioning of the Mold or the number of molds and the type of Cooling.

In the device B is the inductor 3 an indoor ring shower 22 downstream. The indoor ring shower 22 is on the mold 9 opposite side 23 of the inductor 3 arranged and on a supporting component 24 held, which is the extension of the drawbar 6 forms. The water supply of the indoor ring shower 22 takes place via the hollow drawbar 6 , About the inner ring shower 22 becomes the inner surface 2 of the tubular body 1 additionally cooled immediately after heating, whereby the curing process can be positively influenced.

In the device C in the embodiment according to 3 is the mold 9 in the feed or longitudinal direction L behind the inductor 3 on the supporting component 24 with the interposition of the ball bearing 10 arranged.

This is also the case with the device D, as shown in the 4 can be seen. In the device D is between the inductor 3 and the mold 9 an indoor ring shower 22 arranged for additional cooling of the inner surface 2 of the tubular body 1 ,

The embodiment of the device E (see 5 ) sees two molds 9a and 9b in front. The mold 9a is in the feed direction L in front of the inductor 3 arranged, whereas the mold 9b behind the inductor 3 is positioned.

Also two molds 9a . 9b has the device F according to the 6 on. In the feed direction L in front of the inductor 3 is molding tool 9a on the drawbar 6 rotatably held. The mold 9b is located in the feed direction L behind the inductor 3 and there is also over the ball bearing 10 rotatably mounted. Between the inductor 3 and the mold 9b is an indoor ring shower 22 for additional cooling of the inner surface 2 of the ring body 1 intended.

In the 7 is a tube body hardened according to the invention 1 shown in cross section. You can see the hardened inner layer 17 and the uncured outer layer 18 , Internal tests have shown that a precise adjustment of the hardness profile in the wall 19 of the tubular body 1 is possible. The inner layer 17 can be about two thirds of the wall thickness of the tubular body 1 Precise hardening, whereas the outer layer 18 maintains the desired ductility.

To complete the pipe body 1 to the delivery pipe 25 becomes the tubular body 1 end with flanges 26 . 27 provided, as in the 8th is shown. Preferably, the flanges 26 . 27 adhesive at the ends 28 . 29 of the tubular body 1 established. Each end in front of the tubular body 1 are wear rings 30 inside the flanges 28 . 29 glued.

A

contraption

B

contraption

C

contraption

D

contraption

e

contraption

F

contraption

1

pipe body

2

inner surface v. 1

3

inductor

4

bracket

5

power supply

6

pull bar

7

outer surface v. 1

8th

Outdoor ring shower

9

mold

9a

mold

9b

mold

10

ball-bearing

11

mandrel head

12

effective area

13

Front side v. 11

14

Front side v. 11

15

sloping surface

16

sloping surface

17

inner layer

18

outer layer

19

Wall v. 1

20

feeder

21

thrust bearing

22

Indoor ring shower

23

Page v. 3

24

support member

25

delivery pipe

26

flange

27

flange

28

End of v. 1

29

End of v. 1

30

wear ring

KM

coolant

L

longitudinal direction

LA

Longitudinal axis v. 1

R

rotary drive or rotational movement

s

Wall thickness v. 1

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19809529 C2 [0003]
• - DE 2349913 A1 [0004]
• - US 2556243 A [0005]

Claims (22)

Method for heat treatment of a tubular body ( 1 ) of a conveyor tube, wherein the inner surface ( 2 ) of the tubular body ( 1 ) is heated and hardened, the outer surface ( 7 ) of the tubular body ( 1 ) is acted upon with a coolant (KM), characterized in that the cross section of the tubular body ( 1 ) during the heat treatment by an inside of the tubular body ( 1 ) arranged mold ( 9 . 9a . 9b ) is set. Method according to claim 1, characterized in that the tubular body ( 1 ) by the action of force on the inner surface ( 2 ) through the mold ( 9 . 9a . 9b ) is pressed around. Method according to claim 1 or 2, characterized in that the tubular body ( 1 ) relative to the mold ( 9 . 9a . 9b ) is moved. Method according to at least one of claims 1 to 3, characterized in that the tubular body ( 1 ) is moved in rotation during the heat treatment about its longitudinal axis (LA). Method according to at least one of claims 1 to 4, characterized in that the molding tool ( 9 . 9a . 9b ) is rotated. Method according to claim 4 or 5, characterized in that the molding tool ( 9 . 9a . 9b ) together with the tubular body ( 1 ) is rotated. Method according to at least one of claims 1 to 6, characterized in that the tubular body ( 1 ) in the heat treatment in the longitudinal direction (L) relative to the mold ( 9 . 9a . 9b ) and to a in the tubular body ( 1 ) arranged heating device ( 3 ) is moved. Method according to at least one of claims 1 to 7, characterized in that the inner surface ( 2 ) of the tubular body ( 1 ) by means of an inductor ( 3 ) is heated. Method according to at least one of claims 1 to 8, characterized in that the inner surface ( 2 ) of the tubular body ( 1 ) after heating with a coolant (KM) is applied. Method for manufacturing a conveyor tube ( 25 ) with a tubular body ( 1 ) produced according to at least one of claims 1 to 9, characterized in that the tubular body ( 1 ) at the end with flanges ( 26 . 27 ). Method according to claim 10, characterized in that the flanges ( 26 . 27 ) at the ends ( 28 . 29 ) of the tubular body ( 1 ) are determined by adhesive technology. Device for heat treatment of a tubular body ( 1 ) of a conveyor tube, comprising a heating device ( 3 ) for heating the inner surface ( 2 ) of the tubular body ( 1 ) and means for cooling the outer surface ( 7 ) of the tubular body ( 1 ), characterized by at least one molding tool ( 9 . 9a . 9b ), which in the tubular body ( 1 ) is arranged and the cross section of the tubular body ( 1 ) through the mold ( 9 . 9a . 9b ) is adjustable. Apparatus according to claim 12, characterized in that the molding tool ( 9 . 9a . 9b ) Active surfaces ( 12 ) having the inner surface ( 2 ) of the tubular body ( 1 ) to contact. Apparatus according to claim 12 or 13, characterized in that the tubular body ( 1 ) relative to the mold ( 9 . 9a . 9b ) is movable. Device according to at least one of claims 12 to 14, characterized in that the molding tool ( 9 . 9a . 9b ) on a holder ( 4 ) is rotatably mounted. Device according to at least one of claims 12 to 15, characterized in that the molding tool ( 9 . 9a . 9b ) a circular mandrel head ( 11 ), wherein at least on one end face ( 13 . 14 ) of the spike head ( 11 ) an inclined surface ( 15 . 16 ) is provided. Device according to at least one of claims 12 to 16, characterized in that the molding tool ( 9 . 9a . 9b ) with the in the tubular body ( 1 ) arranged heating device ( 3 ) is coupled. Device according to at least one of claims 12 to 17, characterized in that before and / or behind the heating device ( 3 ) a mold ( 9 . 9a . 9b ) is provided. Device according to at least one of claims 12 to 18, characterized in that the heating device ( 3 ) an indoor shower ( 22 ) assigned. Device according to at least one of claims 12 to 19, characterized in that a rotary drive (R) for rotation of the tubular body ( 1 ) is provided. Device according to at least one of claims 12 to 20, characterized in that a feed unit ( 20 ) for longitudinal displacement of the tubular body ( 1 ) is provided. Device according to at least one of the claims 12 to 21, characterized in that the outer diameter of the mold is adjustable.