JP2560590Y2 - Pretreatment device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment device for pretreatment of painting and plating.

[0002]

2. Description of the Related Art A pre-treatment apparatus for pre-treatment of automobile painting is a degreasing liquid or a coating film in which a large object to be treated such as an automobile body transferred on a hanger of a conveyor is stored in a main tank of a pre-treatment tank. It is immersed in a treatment liquid such as a chemical conversion liquid. A plurality of V-shaped bottoms for accumulating sludge settling on the bottom of the main tank are formed at the bottom of the main tank. At each V-shaped bottom, the sludge collected on the bottom is sucked and discharged out of the tank together with the processing liquid. A sludge discharge pipe is connected (Japanese Utility Model Publication No. 63-761). The processing liquid discharged from the sludge discharge pipe is passed through a filter such as a settling tank to remove sludge, and then returned to the main tank again.

In the pretreatment tank, the processing liquid overflowing from the main tank into the sub-tank is sent to a heat exchanger in order to maintain the processing liquid in the main tank in which the object to be processed is immersed at a predetermined control temperature. A processing liquid circulation pipe for heating and returning the heated processing liquid into the main tank is provided (Japanese Utility Model Publication No. Sho 60-31083).

[0004]

In the conventional pretreatment apparatus constructed as described above, for example, conversion sludge adheres to the inside of a heat exchanger for heating a coating solution, which is a processing solution, so that the heat transfer coefficient is reduced. Therefore, the inside is periodically cleaned with nitric acid. However, if the cleaning frequency is low, it is extremely difficult to completely remove the formed chemical sludge which is stuck in the form of stone. In addition, in order to keep the processing liquid stored in the main tank of the pretreatment tank at a predetermined control temperature, the processing liquid overflowing from the main tank into the sub-tank is sent to a heat exchanger, and the hot water heated by steam is heated. However, the processing liquid overflowing into the sub tank is a relatively high temperature processing liquid existing on the liquid surface of the main tank, and the temperature of the processing liquid sent from the sub tank to the heat exchanger is Since there is no great difference from the temperature of the processing liquid in the main tank heated by the heat exchanger, the heat exchange efficiency of the heat exchanger is never good.

Therefore, the present invention increases the heat exchange efficiency of a heat exchanger that heats a processing solution in a pretreatment tank to a predetermined control temperature, and forms sludge that reduces the heat transmission coefficient inside the heat exchanger. It is a technical problem to prevent adhesion.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an outgoing pipe for sending a processing liquid in a pretreatment tank to a heat exchanger, and a processing liquid heated by the heat exchanger. And a sludge discharge pipe for sucking and discharging sludge settled from the V-shaped bottom forming the tank bottom of the pretreatment tank together with the processing liquid. In the pretreatment apparatus, the sludge discharge pipe forms an outgoing pipe of the processing liquid circulation pipe, and a centrifugal separator that removes sludge contained in the processing liquid discharged from the sludge discharge pipe is interposed in the outgoing pipe. Then, a clean processing liquid from which sludge has been removed by the centrifuge is sent to the heat exchanger.

[0007]

According to the present invention, V which forms the bottom of the pretreatment tank is used.
Since the processing liquid sucked and discharged from the bottom of the letter by the sludge discharge pipe is sent to the heat exchanger and heated, the heat exchange efficiency of the heat exchanger is very good. That is, the temperature of the processing liquid stored in the pretreatment tank is lower as it is closer to the bottom of the tank, and particularly at the V-shaped bottom where the processing liquid tends to stagnate. Heat exchangers that heat up have significantly higher heat exchange efficiency.

[0008] The outgoing pipe of the processing liquid circulation pipe for sending the processing liquid in the pretreatment tank to the heat exchanger is formed by a sludge discharge pipe for discharging the processing liquid containing a larger amount of sludge than ever before. However, since the sludge discharge pipe is equipped with a centrifuge that removes sludge from the processing solution,
A clean processing liquid having a lower sludge content is sent to the heat exchanger. Therefore, it is possible to reliably prevent sludge from adhering to the inside of the heat exchanger, and it is possible to greatly reduce the frequency of cleaning the heat exchanger.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flow sheet diagram showing an example of a pretreatment device according to the present invention.

In FIG. 1, reference numeral 1 denotes a pre-treatment tank comprising a main tank 2 for immersing an object to be processed in a processing liquid and a sub-tank 3 for storing a processing liquid overflowing from the main tank 2. A plurality of V-shaped bottoms 4 for accumulating sludge settling on the bottom of the tank are formed at the bottom of the tank 2, and a sludge discharge pipe 6 for suctioning and discharging the sludge settled and accumulated on each V-shaped bottom 4 by a pump 5. Is connected.

Reference numeral 7 denotes a forward pipe 9 for sending the processing liquid in the pretreatment tank 1 to the heat exchanger 8 and a return pipe 10 for returning the processing liquid heated in the heat exchanger 8 to the pretreatment tank 1 again. The outgoing pipe 9 is formed by a sludge discharge pipe 6, and the outgoing pipe 9 has a centrifugal separator for removing sludge contained in the processing liquid discharged from the sludge discharge pipe 6. Machine 1
1, a clean processing liquid from which sludge has been removed by the centrifugal separator 11 is sent to the heat exchanger 8. The sludge separated from the processing liquid by the centrifuge 11 is discharged out of the system from a drain pipe 12 provided in the centrifuge 11.

The return pipe 10 for returning the processing solution heated through the heat exchanger 8 to the pretreatment tank 1 is connected to the main tank 2.
Is connected to a spray riser pipe 13 that sprays a jet of a processing liquid onto the sludge settled on the outlet-side slope of the main tank 2 and drops the sludge on the tank-side slope of the main tank 2. The spray riser pipe 14 is connected to a circulation pipe 16 for returning the processing liquid overflowing from the main tank 2 into the sub tank 3 to the main tank 2 by the pump 15. Reference numeral 17 denotes a hot water circulation pipe for sending hot water in a hot water tank 19 heated by steam injected from a steam pipe 18 into the heat exchanger 8 by a pump 20.

The processing liquid sent from the main tank 2 to the heat exchanger 8 through the sludge discharge pipe 6 is the lowest temperature processing liquid discharged from the V-shaped bottom 4 formed at the bottom of the main tank 2. Therefore, the efficiency of heat exchange with the hot water sent from the hot water tank 19 to the heat exchanger 8 through the hot water circulation pipe 17 becomes extremely good. Further, in the processing liquid sent to the heat exchanger 8 through the sludge discharge pipe 6, since the sludge is effectively removed by the centrifugal separator 11 on the way, the amount of the sludge adhering to the inside of the heat exchanger 8 is large. To decrease.

According to an experiment, when a processing solution having a sludge content of 450 P.PM discharged from the V-shaped bottom 4 is passed through a filter such as a settling tank which has been conventionally used, the sludge content is about 250 P.PM. .PM, but only about 100 P.P.
M. When the processing liquid from which the sludge has been removed by the centrifugal separator 11 is passed through the heat exchanger 8, the amount of the sludge adhering to the inside of the heat exchanger 8 has been reduced to about one third of the conventional one. In addition, the frequency of cleaning the heat exchanger 8 was also greatly reduced.

[0015]

According to the present invention, the heat exchange efficiency of the heat exchanger that heats the processing solution in the pretreatment tank to a predetermined control temperature is improved, and at the same time, the amount of sludge adhering inside the heat exchanger. Is greatly reduced, and the frequency of cleaning the heat exchanger is greatly reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of a pretreatment apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pretreatment tank 4 ... V-shaped bottom 6 ... Sludge discharge pipe 7 ... Processing liquid circulation pipe 8 ... Heat exchanger 9 ... Outgoing pipe 10 ... Return pipe 11 ··centrifuge

Claims (1)

(57) [Scope of request for utility model registration] 1. An outgoing pipe (9) for sending a processing liquid in a pretreatment tank (1) to a heat exchanger (8), and a processing liquid heated in the heat exchanger (8) is again supplied to the pretreatment tank. A processing liquid circulation pipe (7) comprising a return pipe (10) returning to (1), and sludge settled from the V-shaped bottom (4) forming a tank bottom of the pretreatment tank (1) together with the processing liquid. In the pretreatment device provided with a sludge discharge pipe (6) for suction and discharge, the sludge discharge pipe (6) is connected to the forward pipe (9) of the processing liquid circulation pipe (7).
And a centrifuge (11) for removing sludge contained in the processing liquid discharged from the sludge discharge pipe (6) is interposed in the forward pipe (9), and the centrifuge (11) The pretreatment apparatus is characterized in that the clean processing liquid from which sludge has been removed in (1) is sent to the heat exchanger (8).