FR2841010A1 - Control procedure for thermal treatment machine uses camera and image processor to detect changes of state in components' finishing material - Google Patents

Abstract

The procedure for controlling a thermal treatment machine employs a camera and processor to monitor and analyze images of the treated material, adjusting the machine's heater in accordance with change in state. The processor detects zones for study on successive images of the finishing material before, during and after thermal treatment, determining its state according to changes compared with memorized images, and adjusts the machine's heater. The procedure for controlling the operation of a thermal treatment machine (2) used for components (3) that have a finishing or assembly material that changes state with temperature employs a camera (6) and processor (9) to monitor and analyze images of the finishing material, adjusting the machine's heater (11) in accordance with change in state. The processor detects zones for study on successive images corresponding to the location and condition of the finishing material before, during and after thermal treatment, determining its state according to changes in shape or color, e.g. during polymerisation, compared with memorized images, and adjusts the machine's heater accordingly by means of a controller (10).

Description

The present invention relates to the technical field of the control of

  operation of a heat treatment machine in the general sense.

  The object and the invention find a particular advantageous application in the field of controlling the operation of a machine for heat treatment of parts such as, for example, formed from a support on which the components of the type are mounted, for example, electronic, electrical, electromechanical or mechanical, using a filler material deposited punctually in relation to

component fixing steps.

  The object of the invention thus finds a particularly advantageous application in the technique relating to the assembly of components by reflow in which the filler material is formed by an alloy or by any other operations such as polymerization or crosslinking for which material

  filler is, respectively, a polymer or a resin.

  In the preferred technical field of the invention, various types of machine are known which make it possible to secure the components on a support by the change of state of the filler material. It is thus known to use a heat treatment machine such as an infrared, convection or forced convection oven, whether or not equipped with a controlled atmosphere. It is also known machines for treating the vapor of a transfer liquid

  such as the machines mentioned in the vapor phase or condensing ovens.

  Such a heat treatment machine aims to rapidly and uniformly raise the temperature of the support and of the components up to a temperature slightly higher than the point of change of state of the filler material making it possible to obtain,

  soldering, crosslinking or polymerization of the filler material.

  Knowledge of the exact point of melting, crosslinking or polymerization is important in order to reduce the processing cycle time and thus avoid unnecessary overheating of the workpieces after the change of state of the filler material has was done. In order to ensure a safe and complete change of state for the totality of the filler material placed on the part to be treated, the heat treatment time of the part is increased as long as the quality of the assembly is controlled can only be carried out after leaving the parts of the

heat treatment machine.

  The object of the invention is therefore to remedy the drawbacks stated above by proposing a method allowing the operation of a heat treatment machine to be controlled so that the heat treatment cycle can be adjusted as best as possible to ensure the treatment of the part and in particular the change of state of the filler material. To achieve such an objective, the object of the invention relates to a method for controlling the operation of a machine for heat treatment of parts provided with a filler material which changes state with temperature and consists in detecting by a device for image capture and processing, the change of state of the filler material to control the thermal operation of the processing machine. Another object of the invention is to enable the condition of the parts to be checked.

  processed by such a processing machine.

  To achieve this objective, the method according to the invention consists in using the image taking and processing device: In taking images before, during and after the heat treatment of the part, In analyzing the images taken and in compare them to reference images of the part corresponding to a reference state of the part before and after treatment so as to ensure quality control of the part before and after treatment. Another object of the invention is to propose an installation for controlling the operation of a machine for heat treatment of parts provided with a

  filler material changing state with temperature.

  In accordance with the invention, such an installation comprises: a device for taking and processing images (5) comprising: - at least one camera capable of taking images of the parts through a porthole feed on the processing machine, - and a unit for processing the images taken by the camera comprising means for analyzing images apt to detect the change of state of the input material, A and means for controlling the operation of the heating means of the machine heat treatment, pilots by the image processing unit.

  Various other characteristics will emerge from the description given below in

  reference to the single figure annexed which shows, by way of nonlimiting example, a

  control installation according to the invention.

  According to the single figure, the object of the invention relates to an installation 1 adapted to control the operation of a heat treatment machine 2 in the general sense. For example, such a heat treatment machine 2 constitutes an infrared, convection, forced convection or a machine cited in

  vapor phase or a condensing oven as described by patent FR 2,774,013.

  Such a heat treatment machine 2 which is not part proper of the object of the invention is not described in detail because its constitution and its mode of

  wind operation known to those skilled in the art.

  The machine 2 makes it possible to ensure the heat treatment of a part 3 formed for example of a support fitted with components of all types in combination or not such as electronic, electrical, mechanical or electro-mechanical, organized in an appropriate manner to perform functions specific in relation to their intended application. The processing machine 2 thus makes it possible to assemble the components on the support by the change of state of a filler material deposited punctually in relation to the fixing pastes of the components. In a conventional manner, the filler material is formed by a resin, a polymer or by an alloy. For example, the support constitutes a printed circuit which is equipped with these

  various components to constitute a card or piece 3.

  The installation 1 comprises an image taking and processing device 5 comprising at least one camera 6 of any type known per se. The camera 6 is adapted to take images of at least one, and in general, of a series of parts 3 placed inside the processing machine 2. For this purpose, the processing machine 2 has a porthole 7 through which the camera 6 can view the parts 3 placed inside the processing machine 2. The camera 6 can be mounted on a support placed fixedly or capable of being moved to ensure

  a visualization of different parts 3 or of different parts of parts 3.

  The image processing taking device 5 also includes a unit 9 for processing the images taken by the camera 6. This image processing unit 9 comprises means for analyzing the images taken, able to detect the change in state of the filler material. This processing unit 9 is connected at the output to means 10 for controlling the operation of the heating means 11 of the processing machine 2. In other words, it should be understood that the device for taking and processing images 5 makes it possible to detect the instant when the filler material changes state so that the operation of the heating means 11 of the treatment machine 2 can be controlled to lower the temperature inside the treatment machine 2 to the extent that the state of the material changes

contribution occurred.

  According to a preferred characteristic of implementation, the means of analysis of the wind images suitable for detecting at least one study or test area correspond to a place where the input material is located. In other words, the camera 6 is placed so as to take an image of an area of the room 3 comprising at least one filler material. Such an image can then be analyzed in order to detect the study area corresponding to the visualization of the

filler material.

  According to a preferred variant of embodiment, a series of study areas is chosen and wind characteristics determined on each of these study areas so as to conclude that the state of the filler material changes over the entire piece. 3. In other words, a change in the state of the filler material, observed on the different study areas chosen, allows us to conclude that [all the material

  contribution present on part 3 has changed state.

  According to a preferred characteristic of implementation, the analysis means make it possible to determine the characteristics such as the shape and / or the color of such a study area. Indeed, the change in state of the filler material at the time of reflow results in a significant change in appearance that is perfectly visible. Thus, before fusion, the filler material is dark gray in color, mat and of grainy structure, while after reflow, the filler material is very light gray color, shiny with a smooth and homogeneous structure. The analysis means are thus suitable for detecting this or these appearance characteristics such as

  as the color, shine and / or structure of the filler material.

  The analysis means also include means for comparing the characteristics determined on the different images taken during the heat treatment operation in order to deduce therefrom the change of state of the filler material. The method for controlling the operation of a processing machine

  thermal 2 follows directly from the above description.

  After introduction of parts 3 inside the treatment machine 2, the heating means 11 are controlled to raise the temperature inside the treatment machine 2. The treatment unit 9 controls the camera 6 in order to take

  images of at least one area of room 3 comprising a filler material.

  The processing unit 9 analyzes the different images in order to detect the study area corresponding to the filler material. Processing unit 9 analyzes this area

  study in order to determine characteristics such as shape and / or color.

  l5 The processing unit 9 thus follows the evolution of the characteristics of the study area appearing on the various images taken over time during the phase of

heat treatment of parts 3.

  As soon as the processing unit 9 detects an evolution of the characteristics such as for example the transition from the filler material from a light color to a dark color and / or from a grainy structure to a homogeneous structure, it can be considered that the filler material changes state. The control means 10 then control the operation of the heating means 11 to lower the temperature inside the enclosure of the treatment machine. For example, these control means 10 can control the total shutdown of the heating means 11 insofar as it is considered that the reflow of the filler material is finished. According to a preferred embodiment of the invention, the image taking and processing device 5 is adapted to take images before, during and after the heat treatment of the part 3. Such images are then analyzed and compared with reference images of the part previously recorded and correspond to a reference state of the part before and after treatment, so as to ensure a quality control of the part before and after treatment. It should be noted that the quality control at the input of parts 3, that is to say before the start of the heat treatment operation proper, possibly allows, when detecting faults, not to carry out the heat treatment due to the rejection of parts or

  to mark the parts and / or incorrect areas of the parts detected.

  Likewise, the quality control at the output of the parts 3, that is to say after the heat treatment operation, allows the rejection of the parts or the marking of the parts and / or

defective areas.

  The invention is not limited to the examples described and shown because they are divergent

  changes can be made without departing from its scope.

Claims (7)

  1 - Procedure for controlling the operation of a heat treatment machine (2) of parts (3) provided with a filler material changing state with temperature, characterized in that it consists in detecting by an image taking and processing device (5), the change of state of the filler material to control the   thermal operation of the processing machine.   2 - Method according to claim l, characterized in that it consists of: taking images using the image taking and processing device (5), at least during the heat treatment, l0 to a detect on the images taken, at least one study area corresponds to the visualization of a filler material, To be analyzed on the images taken, each study area in order to determine its characteristics, To and to compare on the different images, ['evolution of the characteristics of   the study area in order to deduce the change in state of the filler material.   3 - Method according to claim 2, characterized in that it consists in analyzing the study areas in order to determine in tent that characteristics, the shape and / or the color of said study areas.   4 - Method according to claim 3, characterized in that it consists in determining the color and / or the shape of the study areas in order to detect the passage of the filler material, from a light color to a dark color, from matt to shiny, and / or from a grainy structure to a homogeneous structure, in order to characterize the change state of the filler material.   - Method according to one of claims l to 4, characterized in that it consists of   define a series of study areas for each of which the characteristics are determined so as to conclude that the state of the filler material changes ['the whole piece.   6 - Method according to one of claims l to 5, characterized in that it consists   after the detection of the change of state of the filler material of the study areas, to control the heating means (11) of the machine in order to lower the temperature of parts processing.   7 - Method according to claim l, characterized in that it consists of [using the image taking and processing device (5): To take images before, during and after the heat treatment of the part, 5. to analyze the images taken and to compare them with reference images of the part corresponding to a reference state of the part before and after treatment so as to ensure quality control of the part before and after treatment. 8 - Installation for controlling the operation of a heat treatment machine (2) of parts (3) provided with a filler material changing state with the temperature, characterized in that it comprises: a device for image taking and processing (5) comprising: - at least one camera (6) capable of taking images of the pieces through a porthole (7) fitted on the processing machine (2), - and a unit (9 ) for processing the images taken by the camera comprising means for analyzing images apt to detect the change in state of the input material, and means (l O) for controlling the operation of the heating means (ll) of the heat treatment machine, pilots by the unit image processing (9).   9 - Installation according to claim 8, characterized in that the wind analysis means suitable for detecting at least one study area correspond to the display of a filler material and to determine the characteristics such as   the shape and / or color of such a study area.   lO - Installation according to claim 8 or 9, characterized in that the analysis means also include means for comparing the characteristics determined on the different images taken in order to deduce the change of state filler material.   ll - Installation according to one of claims 8 to 10, characterized in that the   image pickup and processing device (5) comprising: means for storing reference images of the part correspond to a reference state of the part before and after processing, À and means for comparing the reference images with the images taken by the camera to ensure quality control of the front part and