阅读说明：本技术 具有压力传感器的打标头 (Marking head with pressure sensor ) 是由 乌利齐·拉通德 于 2018-11-21 设计创作，主要内容包括：本发明涉及一种用于验证标记(8)的方法,通过连续地向在打标头(1)的针头壳体(7)中振荡的针活塞(2)供应压缩空气,针活塞(2)在一端处具有将标记(8)引入到表面(4)中的针(3),在振荡过程中在压缩空气供应部(10)中形成压力波动,连续地测量压缩空气供应部(10)中的气压,创建压力曲线,并将其与存储在评估单元(12)中的参考压力曲线进行比较并进行评估。(The invention relates to a method for verifying a marking (8), by continuously supplying compressed air to a needle piston (2) oscillating in a needle housing (7) of a marking head (1), the needle piston (2) having at one end a needle (3) which introduces the marking (8) into a surface (4), pressure fluctuations being formed in a compressed air supply (10) during the oscillation, the air pressure in the compressed air supply (10) being continuously measured, a pressure curve being created and compared with a reference pressure curve stored in an evaluation unit (12) and evaluated.)

1. A method for authenticating a marking (8) by continuously supplying compressed air to a needle piston (2) oscillating in a needle housing (7) of a marking head (1), the needle piston (2) having at one end a needle (3) introducing the marking (8) into a surface (4),

pressure fluctuations are formed in the compressed air supply (10) during the oscillation,

continuously measuring the air pressure in the compressed air supply (10),

a pressure curve is created and compared with a reference pressure curve stored in an evaluation unit (12) and evaluated.

2. Method according to claim 1, characterized in that the pressure distribution of the freely oscillating needle (3) is measured and stored as a free reference pressure curve in the evaluation unit (12).

3. Method according to claim 1 or 2, characterized in that the pressure distribution of the needle (3) which generates the marking (8) is measured and stored as a marking reference pressure curve in the evaluation unit (12).

4. A method according to claim 1, 2 or 3, characterized by determining the frequency of the free reference pressure curve and continuously measuring the frequency of the pressure curve, comparing these frequencies with each other, and generating an error prompt if the frequency of the pressure curve is not less than the frequency of the free pressure curve.

5. Method according to any one of claims 1 to 4, characterized in that the marked reference pressure curve is compared with the pressure curve and in case of a deviation an error prompt is generated.

6. Method according to any of the preceding claims, characterized in that the needle piston (2) oscillates back and forth in the Z direction and the needle (3) presses the marking (8) into the surface (4) by the oscillation and the needle piston (2) is pressed back by compressed air against the surface (4) and by the spring force, during which oscillation the compressed air flows out from the outlet of the needle piston housing (7) of the heading head (1) in a manner surrounding the needle piston (2) and in the maximum retracted position is prevented from flowing over the needle piston (2) by a stop sealing ring (9).

Technical Field

The invention relates to a method according to the preamble of claim 1.

Background

For marking workpieces, various marking systems (markiersysmes) are known which penetrate into the material.

Marking systems are also known in which marking is performed by means of an oscillating, pointed, hard needle which can be moved through at least two coordinates and thereby mark alphanumeric characters and arbitrary symbols (e.g. QR codes, company logos, etc.) on the surface. This principle is similar to that of dot matrix printers, except that only a sharp, oscillating needle presses many dots into the surface of the material in sequence and thereby makes the mark visible.

But has the disadvantage that it is not actually marked due to any disturbing processes. Although the XY coordinate trajectory of the marking point can be monitored, this does not guarantee that the marking has indeed occurred.

102006056388B 3 describes an apparatus for marking a workpiece with a marking tool, which apparatus can be guided by means of a drive along a marking path preset by a control device, which apparatus corresponds to a marking detection unit which detects at least a first and a second process parameter and generates a corresponding first and a second detection signal.

But has the disadvantage that the system is complex and susceptible to interference.

Disclosure of Invention

It is therefore an object of the present invention to provide a method that enables simple verification of a mark by marking a head.

This object is achieved by the initially described method for authenticating a marking having the features of claim 1.

In the method according to the invention, a piston, preferably a needle piston, oscillating in a headed needle housing is continuously supplied with compressed air. The oscillating needle piston has a needle at one end that introduces indicia into the surface.

During the oscillation, pressure fluctuations are formed in the compressed air supply. The pressure in the compressed air supply is continuously measured. A pressure curve is created and compared with a reference pressure curve stored in the evaluation unit and evaluated.

Thus, a method is advantageously provided which is less disturbed and requires less structural changes than known heading methods. A pressure sensor is also provided, which has been arranged on the compressed air supply. The pressure value measured by the pressure sensor is detected and evaluated. The pressure sensor should be very fast and record pressure fluctuation frequencies up to about 10kHz or even higher.

The pressure measurements are plotted over time or stored and evaluated.

For this purpose, the pressure distribution of the freely oscillating needle is preferably first measured and stored in the evaluation unit as a free reference pressure curve. The free reference pressure curve shows the change in pressure over time in the case of a needle that is free to oscillate but has not yet penetrated into the surface for marking once. The frequency of the free reference pressure curve remains substantially constant, ideally constant, over the course of time.

Additionally or alternatively, the pressure distribution of the needle producing the marking is measured and stored as a marked reference pressure curve in the evaluation unit. In this case, a marking needle is understood to mean a needle which penetrates into the surface with each oscillation, i.e. produces a perfect or nearly perfect marking, and penetrates into the surface at least in more than 90%, preferably more than 95%, of each oscillation. The marked reference pressure curve is stored in the evaluation unit.

The actual pressure curve is measured continuously during the marking process. Continuous measurement means that a sufficient number of pressure measurement values are determined such that a continuous pressure distribution can be determined at least by interpolation or the like.

The pressure is measured by a pressure sensor and fed to an evaluation unit. In the evaluation unit, the pressure curve or pressure distribution that can be determined therefrom is compared with a free reference pressure curve and/or a marked reference pressure curve.

Advantageously, the frequency of the free reference pressure curve is determined and the frequency of the pressure curve is measured continuously, these frequencies are compared with one another, and an error indication is generated if the frequency of the pressure curve is not less than the frequency of the free pressure curve. When the needle is free to oscillate, the corresponding needle piston has the largest stroke and the frequency is the largest under the same compressed air conditions. If the needle penetrates into the surface, the stroke naturally decreases, since the piston does not first hit the stop but already hits the surface before, and the frequency becomes greater. If the frequency of the pressure curve is not less than the frequency of the free pressure curve, an error indication is generated. In particular, if the frequencies of the two pressure curves are identical, an error message is generated, i.e. a comparison is made to determine that the pressure curve corresponds at least in terms of frequency to the free pressure curve, i.e. the needle oscillates freely. In the present case there is an error in the marking.

In a further variant of the evaluation, the reference pressure curve of the marking is compared with the pressure curve and an error message is generated in the event of a deviation. The comparison of the pressure curves can be carried out by fourier analysis of the pressure curves and the marked reference pressure curves and by comparing the individual frequencies of the fourier transformation with one another.

Preferably, only the pressure distribution can be subjected to a fourier analysis, and conclusions can be drawn from the occurrence of specific frequencies about, for example, to what extent the needle has worn, whether the hardness of the surface has changed, and other data.

Preferably, the needle oscillates back and forth in the Z direction and the needle presses the mark into the surface by the oscillation. The needle piston (with the needle arranged on one side) is pressed against the surface by compressed air and is pressed back by the spring force. The compressed air and the spring force act together and produce an oscillating movement of the needle piston. During oscillation, compressed air flows around the needle piston and out the outlet from the marking head. Only in the maximum retracted position, the needle piston is sealed by the stop sealing ring, so that no air flows around the needle piston. At this point, the compressed air creates its maximum pressure on the needle piston and pushes the needle piston in the Z direction toward the surface. The needle tip is driven into the surface by the acceleration and inertia of the needle piston and a mark is produced. In this case, the spring is compressed and, after the marker is introduced, the needle piston is moved back to its maximum retracted position by the relaxing spring.

Drawings

The invention is described by means of embodiments shown in the six figures. Wherein the content of the first and second substances,

FIG. 1 is a cross-sectional view of a marking head according to the present invention;

FIG. 2a is a cross-sectional view of a marking head in a marking process according to the present invention;

FIG. 2b is a mark introduced into a surface;

FIG. 2c is a time-dependent pressure profile measured at a pressure sensor;

FIG. 3a is a pressure marking head according to the present invention with a free-oscillating needle;

fig. 3b is a pressure profile over time measured at a pressure sensor.

Detailed Description

The marking head 1 in fig. 1 has a needle piston 2 with a needle 3 arranged on the end of the surface side of the needle piston 2, which needle 3 consists of or has a high-strength material (for example hard metal or diamond), or at least at the tip has diamond. Here, the needle piston 2 is formed in a T-shape in cross section. The needle piston 2 has its maximum width along its head remote from the surface 4 to be worked, but it is not sealed off from the inner wall 6 of the needle housing 7, so that air can flow through between the needle piston 2 and the inner wall 6 of the needle housing 7. The air flow is shown by arrows in fig. 2 a.

The needle 3 is used to introduce the marking 8 into the surface 4.

In the part remote from the surface 4, the needle housing 7 is sealed with respect to the needle piston 2 by means of a stopper seal 9. The sealed region is connected in an air-conducting manner to the compressed air supply 10. The compressed air is continuously passed to the part of the needle housing 7 remote from the surface 4 by means of the compressed air supply 10. The pressure sensor 11 is arranged on the side of the compressed air supply 10 and is capable of recording pressure fluctuation frequencies up to 10 kHz. The pressure sensor 11 is connected to the evaluation unit 12 in an electrically conductive and data-conducting manner. The evaluation unit 12 records the pressure profile measured by the pressure sensor 11 over time t in a memory.

On the surface side, a spring 13 is placed around the T-branch 14 of the needle piston 2, which spring 13 exerts a reaction force on the compressed air and together with the compressed air excites the reciprocating vibration of the needle piston 2 in the longitudinal direction L. In this case the vibration may be 1O to 500Hz, but depending on the design of the needle 2 the frequency may also be lower and even higher.

In the fully retracted position of the needle 4 and needle piston 2 shown in fig. 1, the end of the needle piston 2 on the surface side is closed by a stop sealing ring 9. In this position, the compressed air flowing out of the compressed air supply 10 applies an impact pulse to the needle piston 2 and accelerates the needle piston 2 towards the surface 4. The position of the travel in the direction of the surface is shown in fig. 2 a. The needle piston 2 has moved away from the stop sealing ring 9 and compressed air can flow laterally past the needle piston 2 and out of the needle housing 7 into the surroundings in the section on the surface side of the heading head 1. Whereby the pressure of the compressed air in the portion of the surface side of the inner space of the needle housing 7 is lost. In the position according to fig. 1, the pressure sensor 11 experiences the largest pulse in the fully retracted state. When the needle piston 2 moves downward, the pressure measured by the pressure sensor 11 decreases.

During the downward movement of the needle piston 2, the spring 13 is compressed and the compressed spring 13 again presses the needle piston 2 in the other direction, thereby increasing the pressure again at the pressure sensor 11.

This produces a rapid oscillating movement of the needle 3 for introducing the marking 8 into the surface 4. The movement of the needle 3 takes place along a longitudinal direction L, which here corresponds to the Z direction, while the marking head 1 is moved in the XY plane by means of a control (for example CN control, etc.), and in this case the needle 3 marks an arbitrary symbol (for example a QR code, a company logo, etc.) onto the surface 4. In fig. 2b, the marker 8 is chosen in the form of the number "78".

During the downward movement of the needle 3 in the Z direction onto the surface 4, when the needle tip hits the surface 4, the movement naturally stops and the spring 13 immediately lifts the needle piston 2 up again away from the surface 4. This position is shown in figure 2 a.

The closer the surface 4 is positioned at the heading head 1, the smaller the stroke of the lifting movement of the needle piston 2 and thus the greater the frequency of the reciprocating movement of the needle 3, in other words, the longer the duration of one oscillation cycle.

When the needle 3 hits the surface 4 (i.e. the movement is abruptly stopped), the pressure sensor 11 measures a pulse, which is shown in fig. 2c as an example by the trough of a substantially sinusoidally varying pressure distribution.

The labeled pressure curve is shown in fig. 2 c. The valleys of the pressure curve also provide conclusions about needle wear, the strength of the surface and the depth of penetration of the needle tip into the surface 4. Analysis of the labeled pressure curve can be obtained by fourier analysis of the pressure curve, but is not shown.

Fig. 3a and 3b show the same marking head 1 with an oscillating needle piston 2, but without the surface 4 shown therein. The needle piston 2 is free to oscillate and a free reference pressure curve is measured in fig. 3 b. Since the stroke of the freely oscillating needle piston 2 is greater than the stroke of the marking oscillating needle piston 2, the frequency is smaller, i.e. the duration T1 of the period of the free reference pressure curve is greater than the duration T2 of the period of the marking pressure curve.

In addition, a curve profile is formed in the valleys of the pressure curve as a result of the contact with the surface 4, which curve profile likewise deviates from the curve profile of the marking pressure curve.

It should be determined by means of the pressure sensor 11 and the evaluation unit 12 connected thereto whether the needle 3 actually introduces the marking 8 into the surface 4 during oscillation or vibration, or whether the needle 3 oscillates as freely as possible or is stuck (i.e. does not introduce the marking 8 into the surface 4), etc. For this purpose, the free reference pressure curve previously measured in fig. 3b is stored in the memory of the evaluation unit 12.

The free reference pressure curve according to fig. 3b provides information about the pressure distribution of the marking head 1 in its current state when the needle 3 is free to oscillate and no marking 8 is introduced into the surface 4. During the marking process, the pressure is continuously measured with the pressure sensor 11 according to fig. 2a and transmitted to the evaluation unit 12. The marked pressure curve may be saved, at least temporarily. The marking pressure curve must be continuously distinguished from the free reference pressure curve, in particular in the wave trough. If the needle 3 is free to oscillate within some period or only within one period, for example due to the fact that the surface 4 is too far from the needle 3, the marked pressure curve of fig. 2c assumes the same shape or at least substantially the same shape as the free reference pressure curve of fig. 3 b. By comparing the two pressure curves, it is possible to determine precisely the period of time during which the needle 3 is free to oscillate and the marker 8 is not introduced into the surface 4. An error signal is then generated, the flag 8 is interrupted or at least an indication is given that there is a fault in the marking method.

Furthermore, a labeled reference pressure curve is also stored in the evaluation unit 12. In this case, the reference pressure profile is the reference pressure profile determined when a perfect or at least nearly perfect marking 8 is carried out (i.e. each oscillatory movement penetrates into the surface 4). The marking pressure curve that occurs during the marking process is preferably additionally compared with the free reference pressure curve and also with the marking reference pressure curve. In the case of deviations of the marking pressure curve from the marking reference pressure curve, an error signal is likewise generated, which indicates the presence of irregularities in the marking process. Subsequently, the markers 8 may be automatically picked out, or at least an error prompt may be provided to the operator.

List of reference numerals

1 marking head

2-needle piston

3 needles

4 surface of

6 inner wall

7 needle casing

8 labelling

9 backstop sealing ring

10 compressed air supply part

11 pressure sensor

12 evaluation unit

13 spring

Branch of 14T

L longitudinal direction

time t

Duration of T1

Duration of T2