DE102019007471A1 - Test device for cutting ability testing of cutting tools - Google Patents

Abstract

The invention relates to a test device for the cutting ability of a cutting tool by means of test cuts in a test medium (30), which at least comprises • a device for clamping and for moving the cutting tool (1), • a transport and guide unit of the test medium (30), • a Unit (20) for measuring the force of the cutting tool (1) during a test cut, • a programmable device comprising a microprocessor for controlling movements between the cutting tool (1) and test medium (30) and for data acquisition, the test medium (30) during the test cut a tensile force generating force is loaded via a pretension mass (40) which can be raised, • and with an inclination device (55) for changing a test medium position between angles from 0 ° to 45 ° to the vertical, a pretensioning unit (46) being set up in the device, the two Test medium guide rollers (48, 49, 48 ', 49'), their distances de (A) and angular positions (w) to one another and to the preloading mass (40) are designed in such a way that the preloading mass (40) occupies a small bar distance (M) in the raised position.

Description

The invention relates to a test device for cutting ability testing of cutting tools.

Test devices for checking the sharpness of razor blades are known from the following documents: DE 610 077 A ; FR 2417 760 A1 and US 2,925,730 A .

An arrangement for determining the sharpness of cutting tools for cutting thread-like materials, which are passed through a sample plate, shows the DE 10 2011 107 201 A1 . A force measurement takes place on the test blade during the test cuts.

In a number of test devices, for example in the patent US 2006/0201237 A1 or in the document WO 2017142423 A1 the force is measured on the test medium during the test cut. As a rule, the test medium is tightened and tensioned (preloaded).

All materials, especially plastics, which are generally used in test facilities according to the state of the art, are subject to this stress relaxation, which depends on the temperature and the duration of a tensile load.

Furthermore, there is the effect that, due to the action of the cutting tool during the test cut, there is an additional stretch above the cut or a relief below the cut, which lengthens the test medium and the force measurement is not clear.

In one, in the DE 10 2017 001 589 B3 described arrangement is tightening and tensioning the test medium with a preload. However, it is disadvantageous here that the stress relaxation of the test medium and the test cut access lead to a (mechanical) excitation (oscillation) of the preload mass.

Another test device can be found in the US 5571956 A . This patent shows the functional principle of a test device with a cutting movement over two axes. In addition, a manual inclination adjustment of the test medium is shown, which is used to test smaller and defined sections of the cutting tool.

The invention has for its object to provide a device, preferably for an automated cutting ability test of cutting tools, in which an inclination of the device can be made and in which the oscillation (swinging) of the biasing mass is strongly damped.

The stated object is achieved according to the invention by the features of the main claim, while advantageous developments of the invention can be found in dependent claims.

• Das - vorzugsweise stillstehende - Prüfmedium wird unter konstanter Zugspannung geprüft, wobei die einstellbare zugspannungserzeugende Kraft durch ein Gewicht einer aus einer Ablegeposition anhebbaren Vorspannmasse erzeugt wird. Die Vorspannmasse wird vom Prüfmedium umschlungen und hat keine weitere seitliche Führung, um Reibung durch eine Führung auszuschließen. Wegen der fehlenden seitlichen Führung der Vorspannmasse, die allein durch ihr Gewicht in der Umschlingung des Prüfmediums liegt, neigt die Vorspannmasse zum Pendeln.

The essence of the invention can be outlined as follows:

• The test medium, which is preferably stationary, is tested under constant tensile stress, the adjustable tensile force generating force being generated by a weight of a preloading mass that can be raised from a storage position. The preload mass is wrapped in the test medium and has no further lateral guidance in order to rule out friction due to a guidance. Due to the lack of lateral guidance of the pretensioning mass, which is due to its weight alone in the wrapping of the test medium, the pretensioning mass tends to oscillate.

According to the invention, therefore, a test medium pretensioning unit is set up in the test device, which comprises two test medium guide rollers, the distances and angular positions of which from one another and from the pretensioning mass are designed such that the pretensioning mass assumes a small rod spacing in the raised position. The pendulum movement is thus strongly dampened. The small bar spacing can be a few millimeters, preferably 1 to 3 mm.

The expansion of the force-measuring unit lying in the force flow has a further influence on the preload force and length. Depending on the force transducer used, a change in force is only measured as soon as the force transducer system expands. This stretching also causes a change in the preload and length.

Since the preload mass is raised from a deposit position, no preload control is required; the constant weight always works.

• • eine Halterung und eine Bewegungseinrichtung des Schneidwerkzeugs zum entfernbaren Festklemmen und zur Bewegung des Schneidwerkzeugs,
• • eine Transport- und Führungseinheit des Prüfmediums,
• • die zugspannungserzeugende Kraft wird mittels einer aus einer Ablegeposition anhebbaren Vorspannmasse hergestellt,
• • eine Kraftmesseinheit zur Messung der Kraft am Prüfmedium während mindestens einer Relativbewegung,
• • eine frei programmierbare Vorrichtung, umfassend einen Mikroprozessor mindestens zur Steuerung von Relativbewegungen zwischen Schneidwerkzeug und Prüfmedium und zur Messdatenerfassung.

The device according to the invention for testing the cutting ability of a cutting tool and - when using an abrasive test medium - the wear behavior comprises, in addition to the previously mentioned pretensioning unit, at least:

• A holder and a movement device of the cutting tool for removable clamping and for moving the cutting tool,
• • a transport and management unit for the test medium,
• The tension-generating force is produced by means of a pretensioning mass which can be raised from a storage position,
• A force measuring unit for measuring the force on the test medium during at least one relative movement,
• • A freely programmable device, comprising a microprocessor at least for the control of relative movements between the cutting tool and the test medium and for the measurement data acquisition.

• Das Prüfmedium wird zwischen einer oberhalb des Schneidwerkzeugs liegenden Kraftmesseinheit und einer unterhalb des Schneidwerkzeugs liegenden Vorspannmasse geführt.

Further advantageous and inventive features of the invention can be specified as follows:

• The test medium is guided between a force measuring unit above the cutting tool and a preloading mass below the cutting tool.

The test cuts that can be carried out with the test device in a band-shaped test medium are relative movements between the cutting tool and the test medium; with the cutting tool being moved.

The biasing mass can be designed as a roller or cylinder or as a dumbbell. The test medium can loop around the cylinder or the axis between the dumbbell bodies.

The height of the preload can preferably be adjusted by the weight of the preload mass. The preload force can be set in the range from 10 to 30 N.

In the intervals between the test cuts, the prestressing compound can be deposited in a catch position (deposit position). The pretensioning mass can be brought into the lifting position from the catch position by activating a transport roller, for example by means of a pull roller.

The test medium can preferably be guided between at least one unwinding and at least one winding up transport roller. A length of the test medium can be fixed via clamps during the test cut. The clamps of the test medium are preferably present in the area of a supply roll and in the area of a pull roll.

The conveyance of a length of the test medium, which is conveyed and rolled up at intervals after a test cut, can be specified or measured via a rotary encoder.

The choice of the test medium is important for determining the cutting ability. Depending on the test medium, the parameters of the test change with regard to pure initial cutting ability determination or sharpness testing or a combination of initial cutting ability and cutting durability determination.

The test is suitable to detect tool defects so that the product test can identify faulty tools in the production process.

Suitable film-like cutting media should have good sliding properties, a low film thickness and a high degree of homogeneity. PTFE films with a film thickness between 0.1 and 0.25 mm are therefore preferably proposed for the invention. With regard to the automation of test cuts, the main focus is on the stable mounting of the tool, the tracking of the test medium and the tool change.

A unit controlled by a microcomputer, which regulates and controls all movements, data acquisitions, position measurements, etc., is preferably part of the arrangement according to the invention.

For automated cutting capability testing, gripping robots are used that move the tool into the test medium. The cutting tool gripping mechanism can automatically be moved back and forth between a rest position and a test cut position. This may involve changing the cutting tool. A high positioning accuracy and constant traversing movement are important for the drives. The cutting tool can also be rotated using the gripping mechanism.

In the case of tools (knives) with a curved, particularly long blade, the gripper robot is set up in such a way that the tool is fixed both on the handle of the tool and on the back (top or back of the blade) of the blade. Particularly in the case of gripping robots with a few degrees of freedom, it is advantageous and the technical outlay for constructing the device is simpler if an inclination device is used which shifts the testing device into an angular position that deviates from the vertical.

A slot unit with a slot knife can also be assigned to the test device. The slot unit is actuated by a linear movement. The slitting unit is used in particular for cutting tools with a blunt 'tip'. The slot unit can be used to cut the test medium before each test cut.

The features of the invention can be formed individually or together in various further developments.

The present invention is not limited to the embodiments described above, but also encompasses all embodiments having the same effect in the sense of the invention.

• 1: eine in einem Konstruktionsrahmen ohne Gehäuse angeordnete Prüfvorrichtung;
• 2: die Prüfvorrichtung unter Weglassung eines Konstruktionsrahmens;
• 3: die Prüfvorrichtung mit Blick auf die Rückseite nach 1;
• 4: eine Prüfvorrichtung in geneigter Stellung;
• 5: Ansicht auf Bandführungsrollen, Vorspannmasse (geneigte Prüfvorrichtung);
• 6: Darstellung der Radien-, Winkel- und Abstandsverhältnisse von Vorspannmasse und Bandführungsrollen und
• 7: eine Schlitzeinheit mit Schlitzmesser.

Further details and advantages of the invention are explained in an exemplary embodiment with reference to figures. They show in detail:

• 1 : a test device arranged in a construction frame without a housing;
• 2nd : the test device with the omission of a construction frame;
• 3rd : the test device with a view of the back 1 ;
• 4th : a test device in an inclined position;
• 5 : View on tape guide rollers, pre-tensioning mass (inclined test device);
• 6 : Representation of the radius, angle and distance ratios of the preload and tape guide rollers and
• 7 : a slitting unit with a slitting knife.

The 1 shows a form of an overall concept of the test apparatus. The test device is shown without housing or protective covers. A housing does not have to be present in current use, especially for series tests using a gripping mechanism for the cutting tools. The location of the cutting tool - here as a knife 1 with blade 2nd and handle 4th shown - is to be understood schematically. In the lower range 14 A device compartment for controlling electronic units can be present in the test device.

The tape-shaped test medium 30th is from a supply roll 36 pulled off via transport rollers and further on below the cutting tool 1 lying tape guide rollers and the preload 40 guided. It then runs over a power pulley 21 . See also 2nd .

The power pulley 21 is located below a force measuring unit 20th . The force measuring unit 20th realizes a clear measurement of the forces on the test medium in the main power flow. The force curve is recorded in a force-time diagram, saved and, if necessary, displayed. In addition, the robot moving the tool can signal the 'standardized' length of the tool to the device, so that the recording of force-displacement diagrams and thus an assignment of the diagram course to the exact test (interface) location on the tool is made possible.

In the end, the test medium becomes a pull roller 37 guided. In an alternative embodiment, the severed test medium can also be received in a collecting container instead of being wound up.

The test medium is between two test cuts 30th tracked by means of the pull roller via an electric motor. The test medium is tracked so far that the next tool can be checked again "in section".

The preload is in the intervals between the test cuts 40 in a catch position (storage position) 44 discardable.

Before a test cut is a length of the test medium 30th during the test cut via clamps (in the area of the supply roll) and in the area of the pull roll 37 fixed.
The tool is checked "in section". Forces that occur when piercing or splitting the test medium can be absorbed.

The pull roller 37 is driven by a motor with a belt drive 22 driven and the test medium is rolled up on the pull roller. The transport roller with encoder 24th in the area of force measurement serves to redirect the force. About the encoder 24th the length of the rolled-up test medium is measured. The same length of test medium should preferably always be added after each cut.

After a cut, the test medium is rolled up, the clamp being released beforehand. As a result, the pre-tensioning mass “falls” downwards and lies in the support position. When rolling up using a pull roll, the roll-up length is measured using the rotary encoder.

Immediately after clamping in the area of the supply roll, the test medium is rolled up a little further on the pull roll by means of a pull roll, thereby increasing the preload mass.

• Es wird eine definierte Umdrehungsanzahl der mit dem Drehgeber verbundenen Transportrolle vorgegeben; oder:
  • Das Anheben der Vorspannmasse wird über einen berührungslosen Näherungsschalter überwacht.

There are at least the following options for determining the lifting height:

• A defined number of revolutions of the transport roller connected to the rotary encoder is specified; or:
  • The raising of the preload mass is monitored via a non-contact proximity switch.

The clamps ( 50 ' , 50 " ) of the test medium are only indicated schematically. It is a first clamp on the roll-in side 50 ' available, preferably the holding torque of the drive motor ( 22 ) is used to brake the rotary movement of the pull roller. Furthermore, a second clamp on the supply roll side 50 " used. It can be provided here that mechanical clamping ( 50 " in 5 ) in the area of the storage (rotary movement) of the supply roll or a brake in the area of the preload mass.

The preload mass raised from the drop position 40 lies in the wrapping of the test medium. The test medium is brought to constant preload by the weight of the preload mass. The height of the preload is adjusted by the weight of the preload mass. The amount of the preload force can range, for example, in the range from 10 to 30 N and can be changed by changing the weight.

With very sharp knives, the preload can be lower. It makes sense to use higher weights with heavier knives or with serrated cutting tools (bread knives). In particular, the serrated edge creates a "restless" force curve, so that a higher preload can have a dampening effect.

• • Kraftmessung starten, wenn die Kraft einen Schwellwert übersteigt;
• • Kraftmessung starten, wenn Messer einen Näherungsschalter im Bereich der Startposition „berührt“;
• • Kraftmessung durch einen externen Befehl starten.

The time is recorded via the measuring system. In a further embodiment, an axis can be built into the gripping mechanism of the knife, the path being measured in the axis and a force-path curve being generated in this way (on the way of a “robot intelligence”). The force measurement can be started or triggered in various ways:

• • Start force measurement when the force exceeds a threshold value;
• • Start the force measurement when the knife “touches” a proximity switch in the area of the start position;
• • Start force measurement with an external command.

• • Prüfvorrichtung gegenüber dem Robotergreifer (mit Werkzeug) in eine bestimmte Winkellage bringen,
• • Prüfmedium 30 (zwischen Vorratsrolle 36 und Zugrolle 37) installieren,
• • zweite Klemmung (50") vornehmen,
• • Vorspannmasse 40 aus der Auflageposition 44 durch Zugrolle 37 anheben,
• • Prüfmedium auch mit erster Klemmung (50') klemmen,
• • Schnitt durchführen,
• • nach dem Schnitt Klemmungen entspannen,
• • Prüfmedium mit Zugrolle 37 mit vorgebbarer Aufrolllänge nachfördern,
• • .. und wie zuvor weiter.

In summary, the sequence of a test cut can be specified as follows:

• Bring the test device relative to the robot gripper (with tool) into a certain angular position,
• • test medium 30th (between supply roll 36 and pull roller 37 ) to install,
• • second clamping ( 50 " ) make
• • preload 40 from the edition position 44 by pulling roller 37 lifting,
• • Test medium also with first clamping ( 50 ' ) clamp,
• • make cut,
• • relax the clamps after the cut,
• • Test medium with pull roller 37 re-feed with a predetermined roll length,
• • .. and continue as before.

The 2nd shows the test device with only one construction frame 10 " omitting the construction frame in front ( 10 ' ). Otherwise, the 1 referred.

The preload 40 is in the 2nd shown as a dumbbell, between two cylinders of the same size and weight 40 itself an axis 42 located. In the figure, the test medium wraps around this axis 42 . As with rolling bearings, the flanks or side walls of the barbell are used for centering.

The shape (cylinder or barbell) of the preload 40 should enable the test medium to be centered. The weight of the preload mass can be varied by changing the length of the cylinder (or its weight). Since the preload mass only rests on the test medium or is wrapped around it, the preload mass moves vertically when the length of the test medium changes and rotates almost without friction.

The 3rd shows the test device with a view of the back 1 . Opposite the 1 are now the engine 22 with belt drive and the encoder 24th clearly visible.

With the 4th a test device is shown, which by means of an interchangeable inclination device 55 is tilted against the vertical by an angle (for example 45 °). The test medium is placed over one of the test medium guide rollers 48 (please refer 2nd ) to another test medium guide roller 49 ' guided and after wrapping the preload 40 back over the other tape guide rollers 48 ' and 49 brought.

The 5 is a view of the inclined test device, with the omission of housing parts. Reference symbols as in 4th .

In the 6 there is a representation of the radius, angle and distance ratios of the preload and tape guide rollers. In an inclined position of the device (as in 4th or 5 shown) are the test medium guide rollers 48 ' , 49 ' not horizontally or perpendicular to the position of the test medium, but by an angle α inclined to the horizontal. While, for example, by means of the inclination device 55 the test medium the test medium guide rollers are at an angle of 45 ° to the vertical 48 ' , 49 ' tilted by an angle α / 2 - i.e. 50% = 22.5 ° - of the aforementioned angle against the horizontal. The preload mass increases in the representation of the 5 a small bar spacing M to the test medium guide rollers. For the selected angle of inclination α is the distance between the tape guide rollers with reference numerals A drawn in, the angle between said rollers in relation to the center of the biasing mass 40 the reference number w Has. The sizes A and w are generally dependent on the chosen inclination α , or the interchangeable tilt device used 55 .

In 6 is shown that in addition a slot unit 60 with slitting knife 62 can be provided. The slot unit 60 is operated by a linear movement. The slitting unit is used especially for cutting tools with a blunt tip in order to make a cut in the new test medium before each test cut.

• Die Prüfvorrichtung umfasst mindestens:
  • • eine Halterung und eine Bewegungseinrichtung des Schneidwerkzeugs zum entfernbaren Festklemmen und zur Bewegung des Schneidwerkzeugs 1,
  • • eine Prüfmedium-Transporteinheit zur planen Führung des (vorzugsweise bandförmigen) Prüfmediums 30,
  • • eine am Prüfmedium angreifende, während des Prüfschnitts die Kraft aufnehmende Kraftmesseinheit 20, 21;
  • • eine frei programmierbare Vorrichtung umfassend einen Mikroprozessor mindestens zur Steuerung der Relativbewegung zwischen Schneidwerkzeug 1 und Prüfmedium 30 und zur Messdatenerfassung,
  • • wobei das - vorzugsweise stillstehende - Prüfmedium 30 während des Prüfschnitts durch eine einstellbare zugspannungserzeugende Kraft belastet ist, wobei die Kraft durch das Gewicht der Vorspannmasse 40 erzeugt wird,
  • • eine Prüfmedium-Vorspanneinheit 46, die zwei Prüfmediumsführungsrollen 48', 49' umfasst, deren Abstände A und Winkellagen w zueinander derart ausgebildet sind, dass die Vorspannmasse 40 in angehobener Position einen Kleinstabstand M einnimmt.

In summary, the test device according to the invention can be briefly described as follows:

• The test device comprises at least:
  • • A holder and a moving device of the cutting tool for removable clamping and for moving the cutting tool 1 ,
  • • a test medium transport unit for the flat guidance of the (preferably band-shaped) test medium 30th ,
  • • A force measuring unit acting on the test medium and absorbing the force during the test cut 20th , 21 ;
  • • A freely programmable device comprising a microprocessor at least for controlling the relative movement between the cutting tool 1 and test medium 30th and for data acquisition,
  • • where the test medium, which is preferably stationary 30th is loaded during the test cut by an adjustable tensile force generating force, the force by the weight of the preload mass 40 is produced,
  • • a test medium pretensioning unit 46 , the two test medium guide rollers 48 ' , 49 ' includes their distances A and angular positions w to each other are designed such that the preload 40 a small bar spacing in the raised position M occupies.

Reference list

1

Cutting tool (knife)

2nd

blade

4th

Handle

10 ', 10 "

Construction frame (front - rear)

14

Device or electronics compartment

20th

Force measuring unit (force transducer)

21

Power pulley

22

Belt drive motor

24th

Transport roller and encoder

26

Transport roller

30th

Test medium (cutting medium)

36

Supply roll

37

Pull roller

40

Preload

42

Axis (barbell axis)

44

Drop position

46

Preload unit

48, 49

first and second test medium guide role, or 48 ' , 49 '

50 ', 50 "

Clampings

55

Tilt device

60

Slot unit

62

Slitting knife

α

Angular inclination

A

Distance between guide rollers

M

Small rod distance preload to guide rollers 48 , 49 ; respectively. 48 ' , 49 '

w

Angle of center of preload to guide rollers

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 610077 A [0002]
• FR 2417760 A1 [0002]
• US 2925730 A [0002]
• DE 102011107201 A1 [0003]
• US 2006/0201237 A1 [0004]
• WO 2017142423 A1 [0004]
• DE 102017001589 B3 [0007]
• US 5571956 A [0008]

Claims (9)

Device for testing the cutting ability and the wear behavior of a cutting tool (1) by means of test cuts in a test medium (30) during at least one relative movement between the cutting tool (1) and the test medium (30), hereinafter called the test device, which comprises at least a holder and a movement device of the cutting tool (1) for removable clamping and for moving the cutting tool (1), • a transport and guide unit of the test medium (30), • a force measuring unit (20) for measuring the force of the cutting tool (1) on the test medium (30) during at least one relative movement, • a freely programmable device comprising a microprocessor at least for controlling relative movements between the cutting tool (1) and the test medium (30) and for measuring data acquisition, • the test medium (30) during the test cut by an adjustable tension-generating force by means of a liftable force Preload mass (40) is loaded, • furthermore an inclination device (55) for changing a test medium position can be installed, characterized in that in the test device a test medium preload unit (46) is set up which has two test medium guide rollers (48, 49, 48 ', 49 '), whose distances (A) and angular positions (w) from one another and from a pretensioning mass (40) are designed such that the pretensioning mass (40) assumes a small bar spacing (M) in the raised position. Test device after Claim 1 , characterized in that the inclination device is designed as an exchangeable device (55), so that the test medium (30) can be adjusted by the inclination device between angles of 0 ° to 45 ° to the vertical. Test device according to one of the preceding claims, characterized in that the test medium (30) is guided around a pretensioning mass (40) designed as a roller, a cylinder or a dumbbell. Test device according to one of the preceding claims, characterized in that a preload can be adjusted by weights of the preload mass in the range from 10 to 30 N. Test device according to one of the preceding claims, characterized in that the biasing mass (40) can be brought into a lifting position by activating a transport roller (37). Test device according to the preceding claim, characterized in that in the lifting position between the preload mass (40) and test medium guide rollers (48, 49, 48 ', 49') there remains a small rod distance (M). Test device according to one of the preceding claims, characterized in that a length of the test medium (30) is fixed during the test cut by means of clamps (50 ', 50 "). Test device according to one of the preceding claims, characterized in that a conveyance of the test medium (30) can be predetermined or measured via a rotary encoder (24). Test device according to one of the preceding claims, characterized in that a slit unit (60) comprising a slit tool (62) is provided which enables the test medium to be slit before a test cut.

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