WO2002039078A1

WO2002039078A1 - Method for monitoring surface treatment devices that discharge shot blasting abrasives, and a shot blasting pattern verification device

Info

Publication number: WO2002039078A1
Application number: PCT/EP2001/013017
Authority: WO
Inventors: Jennifer Schlick
Original assignee: Jennifer Schlick
Priority date: 2000-11-11
Filing date: 2001-11-10
Publication date: 2002-05-16
Also published as: DE50111821D1; EP1332348A1; DE10055974C1; EP1332348B1

Abstract

The invention relates to a method for monitoring surface treatment devices that discharge shot blasting abrasives involving at least the following method steps: a) positioning a shot blasting pattern verification device (100) comprising a reference plate (10) inside the field of action of a shot blasting adhesive slinging device; b) effecting a blasting toward a reference point defined on the front side of the reference plate (10); c) simultaneously measuring the temperature of the reference plate (10) at a multitude of temperature measuring points Ti,j that are closely arranged inside a measuring grid; d) determining at least one local temperature maximum Mi,j among the multitude of temperature measuring points Ti,j; e) determining a shot blasting abrasive spectrum of action as the location of the absolute temperature maximum inside the measuring grid or as the location of the geometric mean of at least two local temperature maxima.

Description

Method for monitoring abrasive-emitting surface treatment devices and blasting pattern control device

The invention relates to a method for monitoring blasting agent-emitting surface treatment devices and a blasting pattern control device for carrying it out.

In the case of blasting agent-emitting surface treatment devices, a blasting agent is directed onto a workpiece surface, for example by means of centrifugal wheels. Since the swirling of the abrasive in the area of the workpiece surface does not allow visual inspection during operation, the position of the impact area of the abrasive on the workpiece surface, the so-called hot spot, is determined before the workpiece treatment is started with the help of sample placed in the blasting area. Checked sheet metal sections or with a paint application, which is then removed in the area of the beam. However, these methods of checking the beam pattern are imprecise and delay the working cycle. cool the surface treatment facilities, since the aids have to be brought into the blasting area manually and removed from it again.

Furthermore, it is known to use Almen measuring strips named after their inventor, as also described in US Pat. No. 5,731,509-A, for the beam pattern control. These elongated measuring strips consist of layers of spring steel in various thicknesses and are attached to a workpiece or a reference plate, for example by gluing, and then subjected to the blasting agent. This leads to deflections that are measured after blasting. The deflection allows a conclusion to be drawn about the beam intensity and thus a more precise determination of the hot spot, but here, too, continuous monitoring of the beam pattern is not possible. A migrating jet during the ongoing operation of the surface treatment device is not recorded, so that it is only possible with great effort to carry out a jet image check for each individual workpiece. Without a one-off inspection, the quality of the workpiece cannot be guaranteed, and certification requirements, e.g. B. according to DIN ISO 9001 ff., Are not met.

It is therefore the task of specifying a method with which a continuous control of blasting agent-emitting surface treatment devices is guaranteed and a workpiece inspection rate of up to 100% can be achieved.

This object is achieved according to the invention in a method of the type mentioned at the outset, which has at least the following method steps: a) Positioning of a blasting pattern control device with a reference plate in the area of action of a blasting abrasive device; b) rays in the direction of a reference point defined on the front of the reference plate; c) simultaneous measurement of the temperature of the reference plate at a multiplicity of temperature measuring points ι, j, "arranged in a measuring grid. d) determination of at least one local temperature maximum M _if in the set of temperature measuring points _I , J; e) determination of a center of abrasive action as the location of the absolute temperature maximum in the measurement grid or as the location of the geometric center of at least two local temperature maxima.

Abrasives are understood to mean, on the one hand, abrasive particles, in particular quartz sand or carbon dioxide pellets, which loosen loose surface layers such as rust and scale, and, on the other hand, particles, in particular steel balls, which, due to their kinetic energy, compress the workpiece surfaces and thus increase the surface hardness, e.g. , B. in the so-called shot-peening process.

Contrary to the known measurement methods for blasting pattern control, which always detect the direct effect of the blasting medium, the effect of the method according to the invention is used indirectly that, in accordance with the principle of energy conservation, the kinetic energy of the impacting particles of the blasting medium is converted into thermal energy and local heating of the workpiece surface can be registered where the blasting agent impinges. By measuring the temperature at a number of temperature measuring points distributed over the surface, an evaluation device can be used to produce a two-dimensional position image of the beam, be it in the form of a data record that can be processed in a data processing system or in

Form of a visualization which graphically represents the location of the hot spot for the operator of the surface treatment device. Possibility is a polychrome visualization, in which certain color values are assigned to certain beam intensities.

The location of the center of the hot spot on the reference plate is determined by calculating the local temperature maxima. In the case of a workpiece deposited on the reference plate, an abrasive shadow forms on the reference plate, whereas it then changes _. the workpiece around a chain of local temperature maxima is not registered. The geometric center of this ring of local temperature maxima, which corresponds to the center of the abrasive agent effect, can be determined with the desired accuracy, in particular, by known iterative mathematical methods.

With the method of the invention it is therefore possible to continuously monitor and record the blasting position individually and for each blasted workpiece and to move the blasting device in such a way that a targeted reference point on the workpiece or the reference plate and the blasting agent action center determined in accordance with the method Are to be covered.

Further advantageous refinements of the method according to the invention result from the features of subclaims 2 to 4. The invention further relates to a beam pattern control device for carrying out the method, which has at least the following individual parts:

a reference plate with a blasting agent top side and a plurality of temperature sensors arranged in a grid, which are arranged on the rear side facing away from the blasting agent spinning device and / or which are integrated in the reference plate, and an evaluation device.

The beam pattern control device of the invention is characterized by a simple structure. Standard components of measurement technology are combined. The temperature at a measuring point can be measured using the known techniques; Inexpensive and precise temperature measuring devices are already available in large numbers on the market.

The transfer of the measured values of all temperature sensors into the evaluation unit can take place simultaneously or sequentially with such short cycle times between the queries of the individual temperature measuring points that a total snapshot of the beam position results in real time for the viewer.

In an advantageous embodiment of a beam image control device, at least some of the temperature sensors are infrared radiation receivers, which are arranged at a distance from the reference _plate and which can each be focused on one of the temperature _{measuring points} T _lfi ... T _m , _n .

Thus, an image of the infrared radiation on the back of the reference plate can be recorded. This infrared image can be directly displayed graphically and evaluated with image processing algorithms. Individual temperature measurement values of the measurement grid can also be determined from this.

Further embodiments of the beam pattern control device of the invention result from the further subclaims and the following description of an exemplary embodiment.

The invention is explained in more detail with reference to the drawing. The figures show in detail: FIG. 1 a schematic, perspective view of a

Abrasive-emitting surface treatment device;

2 shows a reference plate with a reference beam position image in plan view; 3 shows a reference plate with an uncorrected beam position image in a top view;

4 shows a reference plate with a corrected beam position image in plan view;

Fig. 5 shows a first embodiment and Fig. 6 shows a second embodiment of a reference plate designed according to the invention in plan view.

1 shows a surface treatment device 100, from which a blasting medium is thrown onto a workpiece by means of a centrifugal wheel 110. The centrifugal wheel 110 can be moved in at least one dimension, preferably two-dimensionally, by means of a beam alignment device 120.

The workpiece can be positioned on a front side 12 of a reference plate 10. The hot spot 30, the area the most intense blasting agent effect is represented by the ellipse on the surface 12 of the reference plate 10.

A large number of temperature sensors 15 are arranged on the rear side 14 of the reference plate 10 and are used in blind bores in the reference plate 10. Depending on the number of temperature measuring points, the temperature sensors 15 are connected directly or via a bundling device 130, for example a multiplexer or a bus system, to an input 141 of an evaluation device 140. A signal line can be connected to the beam alignment device 120 from an output 142 of the evaluation device 140. The evaluation device 140 is preferably provided with a visualization device 144, by means of which the operator can directly display and check the beam image.

FIG. 5 shows an embodiment of a reference plate 10 in which temperature sensors 15.1.1 arranged on the rear side 14 thereof. ... 15.x.y are arranged in a two-dimensional Cartesian coordinate system. The Cartesian measuring grid results in a particularly simple arrangement of the sensors and the advantage of simple mathematical calculation methods.

6 shows a further embodiment of a reference plate 10, in which the temperature sensors 15.0.0 ... 15.r.φ are arranged in polar coordinates. This arrangement is advantageous with regard to the mostly circular or ellipsoidal shape of the hot spots 30 that are formed on the reference plate 10.

With regard to an ellipse shape of the hot spot 30, the arrangement of the temperature sensors 15.0.0 ... 15.r.φ can be even further can be optimized if the temperature measuring points are arranged in concentric ellipses and the location of a temperature measuring point can be defined by coordinates r (φ), φ, so that the temperature sensors 15.0.0 ... 15.r.φ are also arranged on ellipsoidal orbits.

In the method of the invention, a reference plate 10 is positioned in the effective area of an abrasive blasting device 110 and blasted in the direction of a reference point 37 (see FIG. 2) defined on the front side 12 of the reference plate 10.

When the abrasive particles hit the surface of the workpiece and / or the reference plate 10, the kinetic energy is converted into thermal energy, which causes a local increase in the temperature of the reference plate 10 depending on the intensity of the abrasive effect.

At the temperature measuring points Tι, ι ... T _m , n shown in FIG. 2, the local temperatures of the reference plate 10 are measured by means of the temperature sensors 15. I arranged there and fed to the evaluation device 140. The current temperature distribution in the reference plate 10 can be recorded by querying all the temperature measuring points T, i ... T _m , _n at the same time or by successively polling at short intervals. The temperature measurement values can be stored in an evaluation matrix with a memory, the storage location coordinates for a temperature measurement value preferably corresponding to the coordinates of the corresponding temperature measurement point in the measurement grid on the reference plate 10.

The values stored in the evaluation matrix can also be visualized using methods known per se, for example by displaying different temperature values as differently colored pixels in a color image.

At least one local temperature maximum Mi, j is determined from all the temperature measurement values determined in the measurement grid. A local temperature maximum M _if j is preferably a temperature measurement value θ at a temperature measurement point T _if j that is greater than a threshold value, which is calculated as explained below: The temperature measurements of all temperature measurement points Tχ, ι - T _m , _n become the arithmetic mean temperature T _M and the absolute maximum temperature T _max determined. The temperature measured value θ of a temperature _measuring point T _if , its temperature, is then defined as the local temperature maximum Mi

θ (Tι.j)> T _M + (T _M - T _ma χ) * F

, preferably F = 0.5 to 1. This weighting enables a sufficiently clear distinction between local temperature maxima and other temperature values in the environment to be achieved.

FIG. 2 also shows schematically the temperature distribution measured in this way on the surface 12 of the reference plate 10. The temperature is the highest in the area of the hot spot 30, as indicated by the dense hatching. The five temperature measurement values of the temperature sensors 15. _I lying in this range lie above the threshold value and are local temperature maxima M _I , J; they are indicated by thick lines in FIG. 2.

Starting from the hot spot 30, the outside temperatures decrease continuously. In temperature zones further out 32, 34 the local temperatures are already below the threshold value and are no longer recorded as local temperature maxima Mι, j.

The geometric center point is determined within the set of local temperature maxima Mι. This then corresponds to the blasting agent action center 36. If there is only one local temperature maximum Mi, j, its location coincides directly with the location of the blasting agent action center 36.

Ideally, the blasting agent action center 36 coincides with the reference point 37 on which the beam was originally aligned.

However, in the case of the deviations in the beam position that usually occur in practice, the abrasive center 36 and the reference point 37 are not congruent. With the method of the invention it is possible to calculate a correction vector 38 (cf. FIG. 3) between the abrasive center 36 and the reference point 37 in a further step. The centrifugal wheel 110 can then be displaced along the correction vector 38 with the at least one-dimensional beam alignment device 120, as a result of which the position of the center of action of the abrasive agent 36 also changes with respect to the measurement grid of the reference plate 10. The reference point 37 and the abrasive center 36 can thus be brought into alignment. The centrifugal wheel 110 is thus precisely adjusted. The tracking along the correction vector 38 can take place during operation. However, the correction vector 38 can also be temporarily stored and then called up in a set-up time, for example during the insertion of the workpieces into the blasting chamber of the surface treatment device 100 Tracking the centrifugal wheel 110 with the jet alignment device 120.

The method according to the invention is explained again below with reference to FIGS. 3 and 4.

A workpiece 20 is positioned on the top 12 of a reference plate 10. The beam from a blasting agent-emitting surface treatment device 100 is aligned with the reference point 37. The temperatures during the blasting to the temperature measurement points T I, ι ... T _m, _n measured, said local temperature maxima Mi, j are determined, which are marked in Fig. 3 as circles with a thick line. The area encompassed by the local temperature maxima M 1, j, shown hatched here, indicates the position and extent of the hot spot 30. The temperature around the hot spot 30 decreases continuously, as indicated by the temperature zones 32 and 34.

The coordinates, of an imaginary geometric abrasive action center 36, can be determined from the set of local temperature maxima Mj. J with sufficient accuracy by known iterative methods.

The hot spot 30, however, does not enclose the workpiece 20 in the illustration selected in FIG. 3, and the abrasive action center 36 determined according to the invention is overall too far to the right above the targeted reference point 37.

By moving the centrifugal wheel 110 along the correction vector 38, the abrasive action center 36 determined according to the invention and the originally targeted reference point 37 are brought into register. With a white tter blasting operation with the blasting device adjusted in this way, the optimized position of hot spot 30 and blasting agent action center 36 results, as is shown in FIG.

Likewise, the extent of the hot spot 30 and — in the case of a non-rotationally symmetrical hot spot 30 — the alignment of its longitudinal axis with respect to the reference plate 10 can be determined using the method and the device of the invention. With an additional rotational degree of freedom of the beam alignment device 120, the centrifugal wheel 110 can be rotated in the plane of the reference plate 12 and the workpiece 20, so that the angular position of the hot spot 30 is optimized and the utilization of the beam area is further improved.

In order to be able to make a correction, the centrifugal wheel 110 and the reference plate 10 must be movable relative to one another. Instead of a jet alignment device 120 shown here, by means of which the centrifugal wheel 110 can be moved at least one dimension, it can also be provided that the centrifugal wheel 110 is arranged in a stationary manner and a movable reference plate 10 is provided.

Claims;

1. A method for monitoring blasting agent-emitting surface treatment devices with at least the following method steps: a) positioning of a blasting pattern control device (100) with a reference plate (10) in the effective range of a blasting agent centrifugal device; b) rays in the direction of a reference point (37) defined on the front side (12) of the reference plate (10); c) simultaneous measurement of the temperature of the reference plate (10) at a plurality of temperature measuring points I, J arranged in a measuring grid; d) determination of at least one local temperature maximum M _{i (} j in the set of temperature measuring points T _I , J; e) determination of a center of abrasive action (36) as the location of the absolute temperature maximum in the measurement grid or as the location of the geometric center of at least two local temperature maxima.

2. The method according to claim 1, characterized in that after step e) a correction vector (38) is calculated starting from the blasting agent action center (36) to the reference point (37) and the blasting agent centrifugal device is moved along the correction vector (38).

3. The method according to claim 1 or 2, characterized in that the temperature values are transmitted in an at least two-dimensional evaluation matrix which is dimensioned in accordance with the extent of the measuring grid and a temperature measuring point Ti, _{j is} assigned to each matrix element.

4. The method according to any one of claims 1 to 3, characterized in that from the temperature measured values of all temperature measuring points ι ₍₁ ... T _m , _n the arithmetic mean temperature T _M and the at least one absolute temperature maximum T _{max are} determined and that as a local temperature maximum Mi, _j a temperature measuring point Ti, j is defined, the temperature of which is, (Ti, j) T _M + (τ “- T _max ) * F, where F = 0.5 to 1.

5. StrahlbildkontroUvorrichtung (100) for performing the method according to one of claims 1 to 4, comprising at least the following parts: - a reference plate (10) having a pressurizable with blasting agent top (12) and a plurality of arranged in ^'a grid temperature sensors (15 ), which are arranged on the rear side (14) facing away from the blasting agent centrifugal device and / or which are integrated in the reference plate (12), and an evaluation device (140).

6. The beam image monitoring device (100) according to claim 5, characterized in that the evaluation device (140) comprises at least one measured value memory, an average value calculation unit and a comparator.

7. spray pattern control device (100) according to claim 5 or 6, characterized in that the temperature measuring points Tι, ι ... T _m , _n are arranged in a Cartesian measuring grid. l. Beam pattern control device (100) according to claim 5 or 6, characterized in that the temperature measuring points are arranged in a polar coordinate measuring grid.

). Beam image monitoring device (100) according to one of Claims 5 to 8, characterized in that at least some of the temperature sensors (15) are infrared radiation receivers which are arranged at a distance from the reference plate (10) and which each point to one of the temperature measuring points ι, ι ... Tπ ,, _n are focusable.

Claims

Summary: (see Fig. 1)

The invention relates to a method for monitoring blasting agent-emitting surface treatment devices with at least the following method steps: a) positioning of a blasting image control device (100) with a reference plate (10) in the area of action of a blasting agent spinning device; b) rays in the direction of a reference point defined on the front of the reference plate (10); c) simultaneous measurement of the temperature of the reference plate (10) at a multiplicity of temperature measuring points Ti, - ,; d) determination of at least one local temperature maximum Mi, in the amount of the temperature measuring points Ti, - ,; e) Determination of a blasting agent action center as the location of the absolute temperature maximum in the measurement grid or as the location of the geometric center of at least two local temperature maxima.