WO1995019453A1

WO1995019453A1 - Workpiece quenching process and device

Info

Publication number: WO1995019453A1
Application number: PCT/EP1995/000083
Authority: WO
Inventors: Günther DISCH; Dieter Haag
Original assignee: Aichelin Gmbh
Priority date: 1994-01-18
Filing date: 1995-01-11
Publication date: 1995-07-20
Also published as: ES2118560T3; CN1143392A; CN1045314C; BR9506525A; ATE165119T1; EP0739426B1; DE59501913D1; EP0739426A1

Abstract

A process and device are disclosed for quenching workpieces (18). The workpieces (18) are exposed to a flow (26) of quenchant (12). The workpieces (18) and the quenchant (12) are reversibly moved in relation to each other. For that purpose, a first conveyor for the quenchant (12), in particular a pump (44), and a second conveyor, in particular a roller conveyor with transport rollers (16) for the workpieces (18), are designed with reversible transport directions.

Description

Method and device for quenching workpieces

The invention relates to a method for quenching workpieces, in which the workpieces are exposed to a current of a quenching agent and the current is set reversibly.

The invention further relates to a device for quenching workpieces, in which the workpieces are exposed to a flow of a quenching means, with a first conveying means, preferably a pump, for the quenching means and with a second conveying means for the workpieces, the first conveying means in its conveying direction is reversible.

A method and a device of the type mentioned above are known from DE-AS 21 43 536.

In conventional systems for quenching workpieces, as are known for example from DE-PS 42 18 126, the workpieces are conveyed on a horizontally running roller conveyor by a quenching device. On their way through the device, the workpieces are acted upon from the bottom in an arrangement designed in the manner of a swelling pot with a quenching agent which flows as liquid from below onto the workpieces, flows through the spaces between the workpieces and then upwards and laterally is led away. For this purpose, a corresponding pump device is provided which enables the liquid quenching agent to flow from below.

From the above-mentioned DE-AS 2143536 a device for achieving uniform cooling in a hardening bath is known. The known device comprises a container with cooling liquid. A conveyor belt, which is provided with holes, is arranged in the hardening bath. The workpieces reach the conveyor belt under the influence of gravity via a conveyor trough, are first conveyed there in a horizontal direction and then transported obliquely upwards out of the bath to an end of delivery.

Propellers with swiveling blades are arranged in the hardening bath. The propellers are controlled by means of a time relay so that the setting direction of the propeller blades changes every 5 seconds, for example. As a result, the direction of flow of the coolant flow, which perpendicularly penetrates the conveyor belt, is reversed each time, so that the coolant flows alternately from top to bottom and from bottom to top through the conveyor belt.

The known device has the disadvantage that the merely perforated conveyor belt with its uniform movement in only one direction results in a noticeable shadow formation. As a result, the workpieces to be cooled are flowed at unevenly despite the cooling flow reversing in the vertical direction, because parts of the workpieces are shaded by the remaining webs in the conveyor belt. This leads to distortion phenomena on the workpieces, which are not portable with many workpieces. The invention is therefore based on the object of developing a method and a device of the type mentioned in such a way that the quenching effect is further improved and that the workpieces can be chamfered without distortion.

This object is achieved according to the method mentioned in the introduction in that the workpieces are moved in a reversing manner on a roller conveyor with rollers transversely to the flow.

The object on which the invention is based is further achieved according to the device mentioned at the outset in that the second conveying means reversely moves the workpieces transversely to the stream and comprises a roller conveyor with rollers.

The object underlying the invention is completely achieved in this way.

In contrast to the device according to DE-AS 21 43 536, shadow formation on the workpieces is completely avoided by superimposing a horizontally reversing movement of the workpieces on the vertically reversing movement of the coolant. In addition, the workpieces are located on a roller conveyor on which they rest only in a line or point. The workpieces are therefore washed around in a double back and forth movement, with no shadow effect on the workpieces due to the minimal support of the workpieces on the roller table. In this way, particularly intimate contact between workpieces and quenching means is achieved, so that all areas of the workpieces come into contact with the quenching means within a very short time. Practical tests have shown that the quenching effect and freedom from distortion of the workpieces can be significantly increased in this way.

According to one embodiment of the invention, the quenching effect and the freedom from warping can be further increased by constricting the rollers in such a way that the workpieces rest only on circumferential cutting edges of the rollers. The workpieces are therefore only stored at points.

In this way, an improved quenching effect is achieved in the contact area of the workpieces compared to conventional devices. This further increases the freedom from distortion of the workpieces.

In preferred embodiments of the method according to the invention, the quenching agent is a liquid or a mixture of a liquid and a gas. The gas can be air or an inert gas. In the latter case, a change in the surface quality of the workpieces is avoided.

The liquid is preferably water, but can also be another conventional quenching liquid. The use of an anti-rust agent is particularly preferred because this prevents the surface of the still warm workpieces from oxidizing immediately. If a mixture of liquid and water is used, it is preferred if the mixture is set with a liquid content between 1 and 250 liters per square meter of workpiece surface per minute at a speed of 10 to 30 m per second.

Practical tests which were carried out using the method and the device according to the invention have shown that the quenching effect could be significantly improved. It was also remarkable that workpieces could be hardened with minimal warpage. This is particularly important in the case of certain workpieces, for example roller bearings, in which optimal distortion results have an immediate and considerable economic impact. The invention can therefore be used with particular advantage in this type of workpieces.

Further examples result from the drawing and the attached description.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the present invention.

Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

Figure 1 shows a first embodiment of a device according to the invention, in side view, highly schematic. FIG. 2 shows the arrangement according to FIG. 1 in a front view;

3 shows a second exemplary embodiment of a device according to the invention;

4 shows a detail of a roll for use in one of the devices according to FIGS. 1 to 3.

A first exemplary embodiment of a device according to the invention for quenching workpieces is designated by 10 in total. The quenching device 10 is connected to an upstream annealing furnace 20 via a relatively narrow furnace outlet 22.

The quenching device 10 has a closed quenching chamber 11, the lower part of which is designed as a trough 14. In the tub 14 there is a quenching bath with a quenching agent 12 in the form of an oil bath, water bath or salt bath.

A transport device 15, which is designed in the form of a roller conveyor with rollers 16, runs across the quenching chamber 11. The roller conveyor 16 is guided horizontally from the furnace 20 through the furnace outlet 22 across the quenching chamber 11 and continues in an outlet area 19 outside the quenching chamber 11. The rollers 16 of the transport device 15 serve as a base for metallic workpieces 18.

In the middle of the quenching chamber 19, a channel, generally designated 25, is arranged below the transport device 15 and has a channel section 24 open at the top. The channel section 24 widens in its upper region and opens directly below the rollers 16. The workpieces 18 are in the quenching position shown in FIG. 1 above the space enclosed by the upwardly open channel section 24. The upwardly open channel section 24 continues above the rollers 16 in the form of a correspondingly shaped frame 34 with laterally closed valves. The frame 34 is open at the top. The frame 34 is connected via vertical holders 35 to a hood 32 which surrounds the frame 34 from the outside and reaches with its lower end as far as the rollers 16 of the transport device 15. The frame 34 can be moved together with the hood 32 in the vertical direction via a lifting device 46.

In the position shown in FIG. 1, the workpieces 18 have already been moved on the roller conveyor to a designated quenching position and are enclosed there by the frame 34, which was lowered from above when the roller conveyor was stationary. The quenching process can now begin.

For this purpose, quenching liquid is first pumped in the direction of an arrow 26 from below through the upwardly open channel section 24, so that the workpieces 18 are flooded with quenching means 12 from below. The quenching means 12 rises within the frame 34, then emerges laterally outwards over the walls of the frame 34 and runs back down into the quenching bath 12 within the area enclosed by the hood 32. The quenching process has not yet been initiated in FIG. 1. In this case, the liquid level 48 of the quenching means 12 is still below the roller conveyor and is of equal height both inside and outside the channel 25. In Fig. 2 it is shown that the quenching means 12 has already risen within the upwardly open channel section 24 beyond the rollers 16 on which the workpieces 18 lie.

From FIG. 2 it can also be seen that the upwardly open channel section 24 tapers downward in its lower region and opens into a horizontal pressure port 36, which in turn is connected to a vertical, upwardly open intake port 42. A pump device 44 is provided above the intake port 42 and projects into the intake port 42 with an impeller 43.

In this respect, the device 10 described so far corresponds to the prior art in accordance with DE-PS 42 18 126 mentioned at the beginning.

The pump device 44 is designed such that the impeller 43 can be moved in opposite directions, as indicated by an arrow 45. Because of this, it is possible with the device according to the invention to set the current (double arrow 26) of the quenching means 12 in a reversing manner, so that a liquid column is set in the upwardly open channel section 24, which moves oscillatingly up and down.

This is indicated in FIG. 2 by the fact that above the workpieces 18, a lower liquid level is drawn in the left half with 48 and in the right half with 48 ″ an upper liquid level. The liquid column in the channel section 24 oscillates between these extreme values 48 'and 48' * ', as indicated by a further arrow 49. The workpieces 18 are completely washed around in this way.

Another special feature of the device 10 is indicated in FIG. 1. There, a double arrow is drawn in at 55 to illustrate that the workpieces 18 on the rollers 16 can be moved not only in the feed direction 27 provided per se, but also in a reversing manner. For this purpose, the roller conveyor is controlled so that the workpieces 18 in the position of FIG. 1 are moved back and forth in rapid alternation. In Fig. 1, this is also indicated by dash-dotted lines with 18- '.

Alternatively (not shown), the roller conveyor 16 can also be moved in a vertical direction or in a direction perpendicular to the plane of the drawing in FIG. 1 in order to obtain a movement relative to the flow 26 of the quenching means 12.

The two aforementioned possibilities of reversing adjustment of the flow 26 of the quenching means 12 on the one hand and the movement 55 of the workpieces 18 on the other hand can be used both alternatively and together.

3 shows a further exemplary embodiment of the invention.

A quenching device 100 comprises a quenching chamber 111, through which a roller conveyor with rollers 116 is guided. Workpieces 118 are located on the rollers 116. In this respect, the view according to FIG. 3 corresponds to that of FIG. 2 for the first exemplary embodiment described above. The workpieces 118 thus move perpendicular to the plane of the drawing in the illustration in FIG. 3.

Above or below the rollers 116 there is a hood 160 or 161, the open cross-sectional area of which is limited in the area adjacent to the rollers 116 such that a predetermined batch of workpieces 118 can in turn be encompassed laterally.

The hoods 160, 161 are connected to pipes 165 and 166, in which there are blowers 167 and 168, respectively. Air can be sucked in laterally by means of the fans 167, 168, as indicated by arrows 169, 170.

In the transition of the pipelines 165, 166 into the hoods 160, 161, liquid lines 175, 176 open into the hoods 160, 161 from above. This takes the form of spray heads 177, 178 arranged there.

Liquid can be supplied via the liquid lines 175, 176, as indicated by arrows 179, 180.

When liquid is supplied (179, 180) and air is sucked in (169, 170), an air flow forms in the pipes 165, 166, as indicated by arrows 185, 186. The air flow mixes in the area of the spray heads 177, 178 with the supplied liquid, so that a mixture 190 or 191 of air and liquid is sprayed or sprayed onto the workpieces 118 from above or from below. By alternately adjusting the blowers 167, 168 or the spray heads 177, 178, the workpieces 118 can be charged with the mixture 190 or 191 alternately from above and from below.

Of course, it is also possible in this case, too, to set the workpieces 118 in motion by correspondingly reversing the rollers 116, as has already been described above for the first exemplary embodiment.

In the exemplary embodiment according to FIG. 3, water is preferably used as the liquid, a rust preventive also being added to the water or being able to be replaced entirely by rust preventive.

Instead of using air as the gas, as described, an inert gas can also be supplied via the blowers 167, 168.

It is preferred if the mixture 190, 191 is set with a liquid content of between 1 and 250 liters per square meter of workpiece surface per minute at a gas speed of 10 to 30 meters per second.

Finally, FIG. 4 shows a special design feature of the rollers 16 and 116 used.

The rollers 16, 116 are namely with circumferential constrictions

80 provided, between which circumferential cutting edges 81 are arranged. If the workpieces 18, 118 now rest on the rollers 16, 116, the support is punctiform because the cutting edges

81 only have a circumferential line as a support option. The quenching devices 10, 100 can otherwise be operated in the usual way. For this purpose, the furnace batch, which has been heated to the hardening temperature, is moved through the quenching device 10, 100 via a rapid speed. According to the described exemplary embodiments of the invention, the quenching means 12 is now guided past the workpieces 18, 118 to be cooled. Alternatively or simultaneously, a reversing movement of the workpieces 18, 118 is carried out via the roller conveyor. The oscillating movement of the quenching means 12 or the workpieces 18, 118 achieves optimal warping results for the workpieces 18, 118.

In the exemplary embodiment according to FIG. 3, the described oscillating effect is achieved via the water-air mixture 190, 191, which is supplied alternately from above and from below. A reversing movement of the workpieces 118 can also be provided here.

Instead of water, a quenching emulsion can also be injected into the airflow. In addition, a rust inhibitor can be added to the water to prevent rusting of the workpieces in the subsequent tempering process.

When using a quenching emulsion, it is possible to delay the collapse of the vapor skin (suffering frost temperature) to higher temperatures. In the subsequent residue-free evaporation of the emulsion, the usual washing process can also be dispensed with.

Depending on the application, one of the usual protective gases can also be used instead of air to prevent any surface oxidation. The cooling process can be controlled in all cases depending on the material and its dimensions depending on its intensity are so that, for example, the inevitable strong temperature differences in the interior of the workpiece in the lower temperature range can be intercepted and compensated.

All in all, all the prerequisites for hardening that is largely free of distortion are met in this way.

Claims

claims

1. A method for quenching workpieces (18; 118), in which the workpieces (18; 118) are exposed to a stream (26; 190, 191) of a quenching agent (12) and the stream (26; 190, 191) is reversing is set, characterized in that the workpieces (18; 118) are moved in a reversing manner on a roller conveyor with rollers (16; 116) transversely to the stream (26; 190, 191).

2. The method according to one or more of claim 1, characterized in that the current (26; 190, 191) is adjusted in the vertical direction and the workpieces (18; 118) are arranged in a horizontal plane.

3. The method according to one or more of claims 1 or 2, characterized in that the quenching means (12) is a liquid, which is preferably mixed with a gas (169, 170).

4. The method according to claim 3, characterized in that the gas (169, 170) or an inert gas is air.

5. The method according to one or more of claims 3 or 4, characterized in that the liquid (179, 180) is water.

6. The method according to one or more of claims 3 or 4, characterized in that the liquid (179, 180) contains an anti-rust agent.

7. The method according to one or more of claims 3 to 6, characterized in that the mixture (190, 191) is set with a liquid content between 1 and 250 liters per square meter workpiece surface per minute at a gas speed of 10 to 30 meters per second.

8. The method according to one or more of claims 1 to 7, characterized in that the workpieces (18; 118) on the roller conveyor are stored point-like (81).

9. Device for quenching workpieces (18; 118), in which the workpieces (18; 118) are exposed to a stream (26; 190, 191) of a quenching means (12), with a first conveying means, preferably a pump (44; 167, 168, 175, 176) for the quenching means (12) and with a second conveying means for the workpieces (18), the first conveying means being reversible in its conveying direction (26), characterized in that the second conveying means comprises the workpieces (18; 118) reversely moved transversely to the stream (26; 190, 191) and comprises a roller conveyor with rollers (16; 116).

10. The device according to claim 9, characterized in that the rollers (16; 116) are provided with constrictions (80), such that the workpieces (18; 118) only on peripheral cutting edges (81) of the rollers (16; 116) lie on.