Tool measuring device for machine tools

Abstract

A tool measuring device for a machine tool includes a transmitter portion (100) and a receiver portion (300). The transmitter portion includes a light source (102) for generating a light beam (104), and the receiver portion includes a detector for detecting the light beam (104), the light beam being transmitted along an optical path from the light source to the detector. At least one of the receiver portion (300) and the transmitter portion (100) includes a protective device including a gas vent (108) configured to discharge vent gas supplied from an external gas source. The optical path also passes through the gas vent (108). The protective device further includes a check valve (112; 200) located in the optical path. Vent gas is supplied to the gas vent (108) through the check valve (112; 200), and the flow of vent gas through the check valve (112; 200) causes the check valve to be in an open configuration, which defines a passage through which the light beam (104) can pass.

Description

Technical Field

[0001] The present invention relates to a tool measuring device for machine tools, and particularly to improvements related to protecting such device from the intrusion of machine tool contaminants such as cutting debris and coolant fluid. Background Technology

[0002] It is known to install tool measuring devices (such as laser tool setters) within the machine tool housing to allow measurement of various tools used for machining workpieces. Removing the tool measuring device after tool measurement is impractical; therefore, such devices must be able to withstand the harsh conditions within the machine tool housing during workpiece machining (e.g., cutting, grinding, etc.). In particular, the tool measuring device needs to be resistant to damage from jets of cutting debris (e.g., chips, scrap, etc.) and exposure to high-pressure jets of corrosive liquid coolants.

[0003] EP 1050368 and EP 1502699 describe examples of tool measuring apparatus in which a laser beam is transmitted from a transmitter section to a receiver section via a free-space region. Tool measurement is performed by simultaneously measuring the amount of light transmitted to the receiver section as the tool is moved into and / or out of the laser beam. To protect the various optical components of the apparatus, the laser beam enters and exits the apparatus via narrow channels or conduits in each of the transmitter and receiver sections. Each channel (e.g., through a drilled hole) is formed at an angle to the optical axis along which the laser beam travels between the transmitter and receiver. Air is exhausted from the channels and is oriented away from or at an angle to the free-space optical path traversed by the laser beam to reduce turbulence effects that would otherwise degrade measurement accuracy. These angled air channels are described in, for example, in EP 1050368. Figure 4 c and EP 1502699 Figure 4 It is displayed in the middle.

[0004] CN 203792103 describes another laser tool setting device with a protective window that uses a protective airflow. Air is supplied to the protective window through a duckbill valve.

[0005] It is also known to include a movable baffle within a tool measuring device to protect internal optical components. For example, US10330464 describes (see, for example, Figure 5 and...) Figure 6 (and related descriptions) A spring-loaded pneumatically sealed piston is used to protect the laser measurement section of the device when no air is expelled. Various baffle arrangements for tool measuring devices are also described in WO 2020 / 183155 and CN 213615607 U.

[0006] The NC4 non-contact tool setting system is sold by Renishaw plc of Wotton-Under-Edge, UK. This device includes angled air vents of the type described in EP 1050368 and EP 1502699, combined with pneumatically activated spring-return baffles positioned upstream of the air vents. These baffles prevent debris intrusion when the air supply is interrupted, thus providing protection for the device's optical components even in the absence of an air supply. Summary of the Invention

[0007] The above-described arrangements provide different levels of protection against contaminants. However, the inventors have found that they do have certain drawbacks, especially when the equipment is exposed to the most severe conditions found in some machine tool systems. For example, venting or releasing air through orifices provides a compact solution, but this only provides protection when an airflow is available. The use of pneumatically activated baffle seals can be arranged to provide protection in the absence of an air supply, but such arrangements are not particularly compact and have various moving parts and seals that may wear over time, allowing contaminant intrusion. According to the NC4 product mentioned above, using pneumatically activated baffles in conjunction with air vents allows protection to be maintained even in the absence of a supplied air, but under severe conditions, contaminants can still enter the orifices when no air is supplied. These contaminants can then accumulate in the air passages, and / or they can reach the pneumatically activated baffle arrangement, thereby degrading or damaging components of the seals.

[0008] According to a first aspect of the present invention, a tool measuring device for a machine tool is provided, comprising:

[0009] The device comprises a transmitter section and a receiver section. The transmitter section includes a light source for generating a light beam, and the receiver section includes a detector for detecting the light beam, which travels along an optical path from the light source to the detector.

[0010] At least one of the receiver and transmitter sections includes a protection device comprising a gas vent configured to discharge vent gas supplied from an external gas source, through which the optical path also passes.

[0011] The protection device also includes a check valve located in the optical path. The venting gas is supplied to the gas discharge port through the check valve, and the flow of the venting gas through the check valve causes the check valve to be in an open configuration, which defines the path through which the light beam can pass.

[0012] Therefore, a tool measuring device suitable for measuring tools on a machine tool is provided. A light beam is transmitted along an optical path from a transmitter section to a receiver section. The optical path may include reflections from the tool under test. In a preferred embodiment, a beam interruption configuration is provided, in which the machine tool carries the tool under test and moves the tool to interrupt the light beam arranged to transmit (in the absence of the tool) from the light source to the detector. Analyzing the intensity of the received light at the receiver section allows the size or properties of the tool under test to be obtained. The machine tool environment may be harsh (e.g., due to coolant, cutting debris, etc.), and at least one or preferably both of the transmitter and receiver sections include protective devices to help prevent contaminant ingress. In particular, light may exit (for the transmitter section) and / or enter (for the receiver section) of the device via gas vents (through which gas (e.g., air) flows as well). This gas venting or gas release helps prevent contaminants from the machining process from entering the device through the gas vents(s).

[0013] In addition to providing gas venting, the protective device includes a check valve to prevent contaminant ingress when no gas is being discharged through the gas vent. In a preferred embodiment, the check valve, such as a duckbill valve, is located in the optical path of the beam within the respective transmitter and / or receiver section. The check valve (which may also be referred to as a one-way valve) is configured to open when gas flows through it toward the gas vent (i.e., in an open configuration). This check valve does not require an actuator or other associated device to force it to open; simply allowing airflow through the check valve provides the force to open it. In this open configuration, there is a passage through the check valve, through which the beam can also pass. In the absence of such gas flow, the check valve closes and, as explained below, provides a tight fluid seal. This prevents external contaminants (such as pressurized coolant jets or cutting debris directed toward the gas vent) from passing through the check valve.

[0014] The tool measuring device of the present invention offers several advantages over prior art tool measuring devices. For example, the check valve can be much smaller than the piston-activated baffle arrangement of the prior art. This allows the check valve to be placed closer to the gas vent than the baffle arrangement, thereby reducing the depth to which contaminants penetrate into the device. In a preferred embodiment, the check valve can be placed downstream (from the perspective of the venting gas) of various optical components (including any optical apertures) in the transmitter and / or receiver sections, and thus can help prevent contaminants from reaching any of these optical components. As explained below, the check valve is also typically a low-cost item, and in one embodiment, it can be easily replaced if damaged or worn. In this way, an improved tool measuring device is provided.

[0015] Advantageously, the check valve of the protection device is in a closed configuration when no vent gas is supplied to the gas vent of the protection device. This closed configuration provides a seal that essentially prevents the intrusion of fluid or cutting debris from the machine tool environment. In other words, when no vent gas is discharged through the gas vent, the closed check valve conveniently prevents most fluid (or other contaminants) that might enter the vent from proceeding forward. The application of negative gas pressure can be used to close the check valve more tightly. Similarly, any external gas pressure (i.e., that would cause backflow of gas without a check valve) can also contribute to a tighter closure of the check valve. In the closed configuration, the check valve also essentially blocks the beam of light from passing along its path. Therefore, when no vent gas is supplied, the tool measuring device may be unusable for measurement. In other words, the closed check valve provides a passive protection mode in which measurement using the device is impossible.

[0016] Advantageously, check valves include duckbill valves. As explained below, a duckbill valve typically comprises two or more flexible lips. These lips can be provided, for example, by a suitable slit surface or multiple resilient flexible valve flaps. These lips can be shaped like a duck's beak. When gas passes through the valve in a first direction, the flexible lips separate to provide an open passage. When there is no gas flow or the gas flow is directed in the opposite direction to the first direction, the lips do not separate but instead remain sealed. The duckbill valve thus acts as a one-way valve or check valve to prevent fluid backflow. The duckbill valve is arranged to open when gas passes through it in a direction toward the associated gas outlet. Therefore, gas flows from a gas inlet or other conduit within the device through the duckbill valve and exits via the gas outlet. A gas supply unit can also be provided to supply this gas flow to the inlet. The duckbill valve can be formed from an elastomeric material, such as silicone, fluorocarbon, or hydrocarbon-resistant fluorosilicone rubber. The duckbill valve may include a first end comprising a flange and a flexible (e.g., elastomer) lip extending from the flange. The duckbill valve may be located within a housing within the transmitter / receiver section, the housing holding the flange and restricting outward deflection of the flexible member. While a duckbill valve is preferred, it should be noted that any check valve that provides passage for the beam when in the open configuration can be used. For example, a slit valve, gate valve, or reed valve would be suitable.

[0017] Advantageously, the gas vent of the protective device includes a conduit angled relative to the optical path, such that the discharged gas is directed away from the optical path. This reduces turbulent gas flow along the free space portion of the optical path, which would otherwise introduce measurement uncertainties. The conduit can also be appropriately sized to avoid interaction with the light beam passing through it.

[0018] As explained above, the transmitter and receiver sections can be arranged in a beam-interrupting configuration, in which the optical path travels from the light source through a free-space region to the detector, and a tool can be placed in the free-space region to block the beam. For example, the light source can guide the beam along a linear optical path arranged to coincide with the detector. The tool under test (DUT) can then be arranged to block the beam (i.e., enter the optical path) in the free-space region located between the transmitter and receiver sections. The tool, by "interrupting" the beam, thus alters the amount of light reaching the detector. Alternatively, the beam can be reflected from the DUT. In such an example, the receiver section can be positioned to collect light emitted from the transmitter section that has been reflected from the tool. In such an example, the optical path includes reflections from the tool. In this reflective arrangement, the transmitter and receiver sections can be located in the same position, or even merged into the same unit.

[0019] The transmitter portion may include a protective device. The receiver portion may include a protective device. In a preferred embodiment, both the transmitter and receiver portions include protective devices. Therefore, the transmitter portion may include a protective device, and the receiver portion may also include (different) protective devices. Therefore, the reference to "protective device" herein includes, where appropriate, a reference to one or each of the protective devices of the device. In other words, in a preferred embodiment, the device preferably includes two protective devices. The transmitter portion may include a first protective device, and the receiver portion may include a second protective device. For simplicity, the first and second protective devices of the transmitter and receiver portions are preferably identical (e.g., interchangeable). However, the first and second protective devices of the transmitter and receiver portions may differ. For example, the size or angle of the gas vent orifice or the size or type of the check valve may differ for the protective devices of the transmitter and receiver portions. Each of the first and second protective devices may have any or all of the features of the protective devices described herein.

[0020] In a preferred embodiment, at least one of the transmitter and receiver portions includes an optical aperture for defining the size of the light beam. Both the transmitter and receiver portions may include such an optical aperture. The size of the optical aperture can be determined to control the properties of the light passing through it. For example, a circular optical aperture can be provided to control the diameter of the light beam and / or prevent stray light from entering the optical system of the transmitter and / or receiver portions. In such an example, even minor contamination of the optical aperture can degrade measurement accuracy (e.g., due to obstruction, deflection, or reflection of the light beam). Therefore, it is preferable that such an optical aperture is located upstream of a protective device. In other words, the check valve (when closed) preferably protects the optical aperture from external contamination.

[0021] The transmitter and / or receiver sections may individually provide a seal against contaminants without any gas flow through the gas vent. Alternatively, at least one of the transmitter and receiver sections may further include a baffle assembly movable between an open and closed position. The baffle assembly may be positioned upstream of the protective device (from the angle of the vented gas). In other words, the baffle assembly may be positioned downstream of the protective device or each of the protective devices. Thus, the baffle assembly can provide a secondary seal to prevent contaminants that have somehow passed through the check valve of the protective device from entering (e.g., in the event of a damaged or worn check valve). In addition to the check valves of the protective devices, the transmitter and / or receiver sections may also include additional check valves (e.g., additional duckbill valves). For example, a series of such check valves may be provided within the transmitter or receiver section along the beam path.

[0022] In a preferred embodiment, both a baffle assembly and an optical aperture are provided. The baffle assembly is preferably located upstream of the optical aperture. The optical aperture can therefore be located between the protective device and the baffle assembly. The protective device thus protects the optical aperture from contaminants entering the gas exhaust port, but the optical aperture is located in front of the baffle assembly (and therefore does not provide protection against external contaminants through the baffle assembly). Thus, the baffle assembly provides additional protection for certain optical components (e.g., detectors or light sources) deeper within the device, but protection for the optical aperture is provided solely by the protective device.

[0023] Advantageously, at least one of the transmitter and receiver sections includes a baffle protecting the gas vent of the device. As those skilled in the art will understand, in the context of this invention, a baffle refers to a device (e.g., a plate, wall, or screen) that deflects the passage of fluid (e.g., a coolant liquid flow). Preferably, both the transmitter and receiver sections include such a baffle. The baffle is conveniently arranged to protect the gas vent from the intrusion of fluid or debris without obstructing the optical path. In other words, each baffle is designed and positioned such that it does not obstruct the beam path but deflects the incident fluid away from the gas vent. The baffle may partially surround the gas vent. The baffle may include a portion of a cone. For example, a baffle including a section or segment of a cone may be positioned to protect the gas vent. The vented gas exiting from the gas vent is preferably oriented away from the baffle. This prevents the baffle from redirecting the vented gas back into the optical path, which would otherwise introduce turbulence.

[0024] Equipment can be formed as a monolithic (one-piece) article that is not intended to be or cannot be disassembled after manufacturing.

[0025] Advantageously, at least one of the transmitter and receiver sections includes a removable cap section that incorporates a protective device. In other words, the removable cap section can incorporate the protective device, and the removable cap section can be attached to the body of at least one of the transmitter and receiver sections. Two such removable cap sections can be provided for attachment to each of the transmitter and receiver sections. The removable cap section, or each removable cap section, may also include the aforementioned optional septum and / or optional optical aperture. In such an example, the cap section can be removed and replaced from the device as needed. For example, a variety of different cap sections can be provided for different measurement configurations (e.g., providing different beam sizes, different gas venting rates, septums of different shapes or orientations, etc.). The cap section can also be removed for replacement or repair purposes. For example, a check valve may wear out or become damaged over time, so the check valve can be easily replaced when needed by replacing the cap section (i.e., replacing the entire cap section with a replacement cap section), or the check valve can be replaced / repaired by removing the cap section. This is especially advantageous when using duckbill valves or similar check valves made of elastomeric materials.

[0026] Alternatively, a machine tool incorporating the aforementioned tool measuring device can be provided. In other words, a machine tool integrated with the aforementioned tool measuring device can be provided. For example, the tool measuring device can be mounted on the bed of the machine tool.

[0027] This document also describes a protective device for a tool measuring apparatus. The protective device includes a gas vent and a check valve, wherein gas flow through the check valve in a first direction causes the check valve to be in an open configuration, which defines a path through which a light beam can pass. The protective device may include any of the features described above in conjunction with the tool measuring apparatus. The protective device may also include an attachment mechanism configured to allow the protective device to be releasably attached, where appropriate, to the housing of the transmitter or receiver portion of the tool measuring apparatus.

[0028] This document also describes a tool measuring device for a machine tool, comprising a transmitter portion for generating a light beam and a receiver portion for detecting the light beam, the light beam being transmitted from the transmitter portion to the receiver portion along an optical path (in which a tool may be inserted), wherein at least one check valve is located in the optical path. The check valve is preferably configured to open when gas flows through it, the open configuration of the check valve defining a passageway through which the light beam can pass. The device may include any of the other features described above.

[0029] This document also describes a tool measuring device for a machine tool. The tool measuring device may include a non-contact tool setter. The device may include a transmitter portion. The transmitter portion may include a light source for generating a light beam. The device may include a receiver portion. The receiver portion may include a detector for detecting the light beam. The light beam may be transmitted from the light source to the detector along an optical path. The tool may be insertable into the optical path. The receiver portion and / or the transmitter portion may include a protective device. The protective device may include a gas vent. The gas vent may be configured to discharge vent gas supplied to the device from an external gas source. The optical path may pass through the gas vent. The protective device may include a check valve. The check valve may be located in the optical path. Vent gas may be supplied to the gas vent through the check valve. The flow of vent gas through the check valve may cause the check valve to assume an open configuration (i.e., the check valve may be a flow-activated check valve). The open configuration may define the passageway through which the light beam can pass. The device may include any of the other features described above. Attached Figure Description

[0030] The invention will now be described by way of example only, with reference to the accompanying drawings, in which;

[0031] Figure 1 A laser tool setting device installed inside the machine tool housing was demonstrated.

[0032] Figure 2 This illustrates the type of existing technology protection device used in Renishaw NC4 products.

[0033] Figure 3 A cross-sectional view of a tool setting device including the protective device of the present invention is shown.

[0034] Figure 4 It shows Figure 3 An expanded view of the equipment's protective device.

[0035] Figure 5A and Figure 5B The diagram illustrates the duckbill valve in both the closed and open configurations.

[0036] Figure 6 It shows that it is suitable for use in Figure 3 and Figure 4 The duckbill valve design used in the equipment

[0037] Figure 7A and Figure 7B These are images of the duckbill valve in its closed and open configurations, respectively.

[0038] Figure 8 It shows Figure 3 and Figure 4 External stereoscopic view of the measuring equipment. Detailed Implementation

[0039] refer to Figure 1 A schematic diagram is provided of a (non-contact) laser tool setter 2 located inside the machine tool housing 4. Specifically, the laser tool setter 2 is mounted on the machine tool bed 6, close to the workpiece 8 to be processed (cut).

[0040] The laser tool setter 2, as an example of a tool measuring device, includes a transmitter section 10 comprising a laser diode and suitable optics (not shown) for generating a beam 12. A receiver section 14 is spaced apart from the transmitter section 10 and includes a photodiode and suitable optics (not shown) arranged to receive the beam 12. In the illustrated arrangement, both the transmitter section 10 and the receiver section 14 are attached to a common base 16 and thus maintain a fixed spacing and orientation relative to each other. The base 16 is securely mounted (e.g., bolted) to a machine bed 6. Other configurations of the device are also possible. For example, a single (common) housing can be provided for the transmitter and receiver, or separate transmitter and receiver units can be separately mounted to the machine tool. The laser tool setter 2 can also be mounted to other parts of the machine tool; for example, to a machine tool housing or to a movable tool setting arm, etc.

[0041] The laser tool setter 2 is arranged such that the laser beam 12 is transmitted from the transmitter section 10 through a free-space region to the receiver section 14. The tool 20, attached to the tool shank 22 carried by the movable spindle 24 of the machine tool, can then be moved to obstruct the laser beam 12. Specifically, the spindle 24 can be moved relative to the bed 6 under the control of the machine tool controller 26. A detector in the receiver section 14 measures the intensity of the light transmitted to it from the transmitter section, and the beam intensity signal is transmitted to the tool setter interface 28 for analysis. The interface 28 includes a processor that analyzes the beam intensity signal and generates a so-called "trigger signal" when the intensity of the received light exceeds a certain threshold (e.g., 50%). This trigger signal is transmitted to the SKIP input of the machine controller 26. Upon receiving the trigger signal from the interface 28, the tool position measured by the machine tool is captured, thereby allowing for tool size (e.g., tool length or diameter) measurement. It should be noted that the trigger signal can be output in several different ways depending on the configuration of the controller 26. For example, a trigger signal can be transmitted communicatively by latching the voltage of the line connected to the SKIP input of controller 26 or by generating a pulse or a series of pulses delivered to this SKIP input. The trigger signal can alternatively be transmitted to controller 26 via a digital data bus (e.g., as described in WO 2018 / 134585).

[0042] The laser tool setter 2 allows various tools (such as tool 20) to be measured before they are used in the cutting process. The subsequent cutting process involves bringing these tools (such as rotary drills or milling tools) into contact with the workpiece 8 to perform the desired cutting operation. A coolant tube 30, which can be carried by the spindle, directs a coolant spray or jet from the cone 32 shown within it to the end of tool 20. The coolant spray is typically activated only during the cutting process to wet the workpiece 8, but the tool setter 2 is subsequently affected by splatter, reflected coolant jets, and cutting debris. This is especially true if the tool setter 2 must be mounted close to the workpiece 8 (as is the case in some machine tool setups).

[0043] refer to Figure 2 A cross-sectional view of the transmitter portion 50 of the aforementioned prior art NC4 tool setting device is provided.

[0044] Laser module 52 includes a laser diode and optics for generating a collimated beam 51. Although a collimated beam 51 is shown, a focusing element can alternatively be provided to generate a focused beam. The beam passes through an optical aperture 56 (which defines the diameter of beam 51) and exits the emitter section 50 via an angled air exhaust port 58. The interior of the emitter section 50 is arranged to include channels that guide airflow from an external compressed air supply through and around the optical aperture 56, such that the airflow exits the device via the air exhaust port 58. The supply of compressed air also acts on a pneumatic actuator (piston) mechanism that overcomes the restoring force of a compression spring 62 to move a baffle 60 out of the optical path. In the absence of a compressed air supply, the spring 62 moves the baffle 60 upward, thereby sealing the hollow channel through the emitter section. This arrangement of the baffle seal and actuator prevents contaminants from reaching laser module 52.

[0045] While the NC4 tool setting system described above has been found to provide highly robust, market-leading protection against contaminants with or without compressed air supply activation, it still has drawbacks when used under the most extreme conditions. Specifically, when there is no air supply, coolant and debris can enter the air vent 58 and may accumulate in the section of the channel in front of baffle 60. Although most of these contaminants are expelled from the device when the air supply is subsequently activated and baffle 60 is opened, some debris may accumulate over time. This could include contaminants that reach and damage baffle 60 and associated actuator components, or reach the laser module 52. Therefore, over time, there may be degradation in the optical and / or sealing performance provided by baffle 60, requiring disassembly and cleaning of the device. It should be noted that although... Figure 2The transmitter section is shown, but similar problems may occur with the corresponding receiver section.

[0046] Next reference Figure 3 and Figure 4 The transmitter portion 100 according to the present invention is shown. Figure 3 As shown, and similar to the prior art transmitter section 50 described above, a laser module 102 is provided to generate a beam 104, which passes through an optical aperture 106 and exits the transmitter section via an air exhaust port 108. A pneumatically activated baffle 110 is also provided between the optical aperture 106 and the laser module 102.

[0047] The transmitter section 100 additionally includes a duckbill valve 112 located in the optical path between the air vent 108 and the optical aperture 106. An external baffle 114 is also provided to help deflect incident contaminants (such as coolant flow) away from the air vent 108. Figure 3 The complete layout of the transmitter section is shown in the image, while Figure 4 A protective cap portion 120 is shown, which can be removed from the remainder of the transmitter portion. In this example, the protective cap portion 120 includes a partition 114, an air vent 108, a duckbill valve 112, and an optical aperture 106. Removing the protective cap portion 120 allows for cleaning of the interior of the remainder of the transmitter portion 100. The entire protective cap portion 120 (or only the duckbill valve 112 within the protective cap portion 120) can also be replaced if it is worn or damaged.

[0048] During the measurement, a compressed air supply is introduced into the equipment.

[0049] Air passes through the duckbill valve 112 and exits the transmitter section 100 via the air vent 108. As will be explained below, the duckbill valve 112 comprises a flexible plastic tube with resilient lips or valve flaps (having the general shape of a duckbill), which expand (open) when there is an airflow through the tube in one direction (i.e., in the direction away from the device). This arrangement allows the beam 104 to also pass through the duckbill valve when the internal passage of the duckbill valve 112 is opened by a compressed air flow. The compressed air supply also actuates a piston actuator to move a baffle 110, thereby exposing the laser module 102. Therefore, the beam 104 is unobstructed when there is a compressed air flow through the transmitter section and out of the air vent 108. When activated, this airflow or air vent also prevents contaminants from entering the air vent 108. It should be noted that proper alignment of the angled duct forming the air vent 108 causes the vented air to be oriented away from the external partition 114, thereby minimizing any air turbulence along the free space portion of the light path. The device may also include a suitable air inlet for receiving air (or any suitable gas) from an external supply device (e.g., a compressed air supply device).

[0050] In the absence of compressed air supply to the transmitter section 100, the baffle 110 seals the laser module 102 and also closes the passage through the duckbill valve 112 (i.e., the lip at the end of the flexible plastic tube is closed, and the valve thus seals itself). Thus, it can be seen that two different protective seals are provided within the optical path. The duckbill valve 112 is located immediately behind the air vent 108 and functions to protect the optical aperture 106 from contaminants when sealed due to the lack of airflow. Further protection for the laser module 102 is provided by the baffle 110. This double-sealing arrangement reduces the ability of contaminants to penetrate the air supply passage within the transmitter section 100, thus providing improved protection against contaminant intrusion. The compactness of the duckbill valve 112 also means that it can be placed closer to the air vent than the relatively larger baffle 110 arrangement, thereby reducing the depth to which contaminants penetrate the device. Similarly, although only the transmitter section is described, a similar arrangement is used in the receiver section.

[0051] Although the described double-sealing arrangement has been found to provide good protection, the baffle 110 can be omitted and the duckbill valve 112 alone can be used to prevent contaminants from entering the device when there is no air supply. In such an example, a much more compact tool setting device could be provided. It should also be remembered that these examples are non-limiting and various other substitutions and variations are possible. For example, the external baffle can be omitted, the size of the air vent can be determined to provide an optical aperture, the collimated laser beam can be replaced by a focused laser beam, etc.

[0052] Next reference Figure 5A and Figure 5B This section will explain the operating principle of a duckbill valve in more detail. A duckbill valve is an example of a check valve and is typically made of rubber or synthetic elastomer. Duckbill valves usually have two or more lips or valve discs that are typically shaped like a duck's beak.

[0053] Figure 5A A duckbill valve 150 in a closed configuration is shown, formed by two valve discs 152a and 152b. In this configuration, there is no fluid flow from left to right as shown in the figure, and the elasticity of the two valve discs 152a and 152b keeps them flat and engaged with each other. This provides protection against fluid ingress. Figure 5A A fluid seal for any fluid flow from right to left.

[0054] Figure 5B A duckbill valve 150 in an open configuration is shown. This open configuration is used when there is fluid flow through the duckbill valve in one direction (from left to right in this example). Specifically, when... Figure 5B As shown, when fluid is pumped from left to right, the flat ends of the duckbill valves 152a and 152b deform and open to allow pressurized fluid to pass through.

[0055] The duckbill valve 150 therefore functions as a check valve or one-way valve. Duckbill valves are commonly used in medical and fluid control applications to prevent contamination due to backflow. They are also functionally similar to the mitral valve in the heart. In recent years, this type of duckbill valve has also been used in low-cost food packaging applications. For example, it allows liquids (such as ketchup, mustard, etc.) to be discharged in a controlled manner from plastic bottles.

[0056] refer to Figure 6 A duckbill valve 200 suitable for use in the aforementioned tool setting device is shown. The duckbill valve 200 includes a flange 202 and a lip 204. The flange 202 allows the valve to be secured within a suitable recess in the transmitter or receiver portion of the aforementioned tool setting device. Importantly, the size of the duckbill valve 200 is chosen such that when the valve is opened by supplying compressed air, the laser beam can pass through the open valve passage (channel). Specifically, the lip 204 is designed to move apart and press against the cavity wall within the transmitter or receiver portion, thereby opening a passage with a diameter larger than the diameter of the laser beam. In the absence of an airflow outlet, a method is employed... Figure 6 The configuration shown prevents backflow. Light passage may also be blocked, at least partially, by the closed valve. The duckbill valve 200 is formed of FKM or a similar elastomer.

[0057] Figure 7A This is an image showing an end view of the duckbill valve when no air passes through. From Figure 7AAs can be seen, the two lips defining the slit are close to each other (i.e., there is only a small gap between the lips). If a small negative gas pressure is provided inside the device, or if there is pressurized gas attempting to flow back through the valve, these lips will seal together more tightly (i.e., preventing gas from flowing back through the duckbill valve).

[0058] Figure 7B This is an image showing an end view of the duckbill valve as air passes through it in the direction of the camera capturing the image. It should be noted that the magnification used to capture image 7B is less than... Figure 7A This allows the structure around the duckbill valve to be visible. From Figure 7B As can be seen, the lips are separated from each other, and there is an opening through which the light beam can pass. The size of the opening is determined to be larger than the light beam, and the light beam and the valve are positioned such that the center of the light beam is on the opening. Therefore, the light beam can pass through the (open) opening without obstruction.

[0059] It should be noted that the elasticity of the duckbill valve can be customized to achieve desired operational performance (e.g., controlling the gas pressure and / or flow rate required to open the valve). This can be done through appropriate material selection and / or by changing the dimensions of valve components, etc. While the examples above illustrate an elastomeric duckbill valve (where the material elasticity alone causes the valve to close when there is no gas flow), additional closing elements can also be provided. For example, a return spring can be attached to the flexible lip of the duckbill valve to provide additional spring force to close the valve (and thus require additional force from the airflow to open the valve). Variations of the duckbill valve shown can also be used. For example, a so-called cross-slit duckbill valve can be employed. Similarly, alternative check valves that allow for implementation of similar functions to the duckbill valve exist. These include reed valves (e.g., formed of flexible metal or composite materials), gate valves, hinged check valves, etc.

[0060] refer to Figure 8 The figure shows a perspective view of the tool setting device of the present invention. The tool setting device includes a transmitter section 100 and a receiver section 300 as described in detail above. The receiver section 300 is configured similarly to the transmitter section 100, but it includes a photodetector module (e.g., including a photodiode) instead of a laser module. An external partition 114 of the transmitter section 100 is visible in the figure, and a similar partition is also provided on the receiver section 300 (although this is not visible in the figure). These partitions are appropriately angled to protect the air vent. Both the transmitter section 100 and the receiver section 300 are attached to a base 302, which in turn can be attached to the desired part of a machine tool. A light beam is transmitted from the transmitter section 100 to the receiver section 300 via a free space region into which a tool can be placed. Appropriate analysis of the received light signal is used to measure the tool already placed in the light beam.

[0061] It should be remembered again that the above are merely examples of the invention, and many variations and alternatives are possible. For example, any light source (not just a laser diode) can be used. Similarly, the detector does not have to be a single element (photodiode). Arrays of light-sensing elements or pixel arrays may also be used. For example, one-dimensional or two-dimensional imaging arrays can be used. A beam interruption device has been described, but protective devices can also be incorporated into other tool measuring devices, such as reflective tool sensors.

Claims

1. A tool measuring device for machine tools, The tool measuring device includes a transmitter section and a receiver section. The transmitter section includes a light source for generating a light beam, and the receiver section includes a detector for detecting the light beam, which travels along an optical path from the light source to the detector. At least one of the receiver section and the transmitter section includes a protection device, the protection device including a gas vent configured to discharge vent gas supplied from an external gas source, the optical path also passing through the gas vent. wherein The protection device also includes a check valve located in the optical path, through which the vent gas is supplied to the gas discharge port, and the flow of the vent gas through the check valve causes the check valve to be in an open configuration, which defines the path through which the light beam can pass.

2. The apparatus of claim 1, wherein, When no venting gas is supplied to the gas outlet, the check valve of the protection device is in a closed configuration to prevent the intrusion of fluid or debris from the machine tool environment.

3. The apparatus of claim 2, wherein, When in the closed configuration, the check valve blocks the light beam from passing along the optical path.

4. The apparatus of any of the preceding claims 1 to 3, wherein, The check valve includes a duckbill valve with multiple flexible lips.

5. The apparatus of claim 1, wherein, The gas discharge port of the protective device includes a conduit that is angled relative to the optical path, such that the discharged gas is directed away from the optical path.

6. The apparatus of claim 1, wherein, The transmitter portion and the receiver portion are arranged in a beam-interrupting configuration, in which the optical path travels from the light source to the detector through a free space region, and a tool can be placed in the free space region to block the beam.

7. The apparatus of claim 1, wherein, Each of the transmitter section and the receiver section includes the protection device.

8. The apparatus of claim 1, wherein, At least one of the transmitter portion and the receiver portion includes an optical aperture for defining the size of the light beam, the optical aperture being disposed upstream of the protective device.

9. The apparatus of claim 1, wherein, At least one of the transmitter portion and the receiver portion further includes a baffle assembly movable between an open position and a closed position, the baffle assembly being disposed upstream of the protection device.

10. The apparatus of claim 9, wherein, At least one of the transmitter portion and the receiver portion includes an optical aperture for defining the size of the light beam, the optical aperture being disposed upstream of the protective device; the optical aperture being located between the baffle assembly and the protective device.

11. The apparatus of claim 1, wherein, At least one of the transmitter portion and the receiver portion includes a partition outside the gas vent of the protective device, the partition being arranged to protect the gas vent from the intrusion of fluid or debris without obstructing the optical path.

12. The apparatus of claim 11, wherein, The vented gas discharged from the gas outlet is directed away from the partition.

13. The apparatus of claim 1, wherein, The removable cap portion incorporates the protective device, and the removable cap portion can be attached to the body of at least one of the transmitter portion and the receiver portion.

14. A machine tool, said machine tool being combined with a tool measuring device according to any one of claims 1 to 13.

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