Laboratory grinding machine

Abstract

The invention relates to a laboratory grinding machine (1) for comminuting grinding material, in particular in the form of a cutting grinding machine, an impact cross grinding machine, a disc grinding machine, a knife grinding machine or a ram grinding machine, comprising a device housing (12), a grinding machine housing (16) and / or a grinding container (17), a grinding chamber (82) located in the grinding machine housing (16) or the grinding container (17), wherein the grinding machine (84) can be arranged in the grinding chamber (82), by means of which the grinding material is comminuted, and wherein the grinding machine housing (16) or the grinding container (17) has a user access opening (94), a grinding machine housing door (18) or a safety cover (19) for closing the user access opening (94), and wherein the grinding machine housing door (18) or the safety cover (19) has an open state and a closed state, wherein a user can access the grinding machine (84) via a user access opening (94) in the open state of the grinding machine housing door (18) or safety cover (19), a grinding machine drive (2, 4) for driving the grinding machine (84), the grinding machine housing door (18) or safety cover (19) having a closure element (22) by means of which the grinding machine housing door (18) or safety cover (19) can be locked in the closed state, and wherein the laboratory grinding machine (1) has a mechanical grinding machine drive locking device (74).

Description

Technical Field

[0001] The invention relates to a laboratory grinder, in particular a laboratory-scale cutting mill, impact cross mill, disc mill, knife mill or punch mill, which has a grinding machine in which the grinding material is comminuted, for example in the gap between a grinding rotor and one or more fixed counter elements, between two discs or by rotor knives or an impact rotor. Background Art

[0002] Cutting mills comminute the grinding material according to the shearing principle between a rotating cutting rotor and one or more substantially axially extending fixed mating cutting elements, the cutting rotor having one or more rotor cutting elements also extending substantially axially. Such laboratory cutting mills are particularly suitable for comminuting viscous or fibrous samples, for example biological samples such as straw or plastic films, to name just a few. Current examples of laboratory cutting mills include, for example, the applicant's 19 and 15, whose basic structure is referred to here. 19 and A corresponding product description of 15 can be found, for example, at www.fritsch.de.

[0003] In these laboratory-scale cutting mills, a more or less free-flowing bulk material is usually introduced into a grinding chamber, for example via a charging hopper, in which a cutting rotor rotates about a horizontal axis. The cutting rotor can have different geometries, for example with straight cutting edges or so-called V-shaped cutting edges. The latter have a swirl and thus achieve a good cutting action, especially when comminuting viscoelastic materials and films.

[0004] Usually, a screen, for example a screen box, is located below the cutting rotor, through which the sample material, which has been comminuted sufficiently intensively, can flow in order to be collected in a collecting container located below it.

[0005] With regard to further construction details of the cutting mill which are known in principle to the person skilled in the art, reference is made to the applicant's cutting mill. 19 and The product description of 15, which at the time of application and publication was available at www.fritsch.de, and the basic structure of this cutting grinder is incorporated by reference therein. In addition, the application documents DE 196 01 594, DE 10 2018 113751 A1, WO 2020 / 200759 A1 and DE 10 2019 133 437 A1 describe such a cutting grinder and are likewise incorporated herein by reference.

[0006] Potential risk of injury to the user of the cutting grinder may lie in the grinding chamber between the rotating cutting rotor and the fixed mating cutting element or mating knife. 16, www.fritsch.de) or a disc grinder (see 13, www.fritsch.de), the product description of which is also incorporated herein by reference. Such laboratory grinders also have rotor grinders in which the grinding material is comminuted between the grinder rotor and a fixed counter element of the rotor grinder. Similar potential risks also occur in knife grinders or in punch grinders, which are sometimes also called rotor high-speed grinders, in which the rotor knives rotate about a vertical axis in the grinding container (see 11, www.fritsch.de), in which an impact rotor rotates in an annular screen about a vertical axis in a grinding container designed as a collecting container (see 14, www.fritsch.de), the product description of which is also incorporated herein by reference.

[0007] In such grinders, the user must be reliably prevented from touching the grinder, in particular the grinding rotor or the area between the grinding rotor and a fixed counter element, for example with his fingers, during the grinding process and from starting the grinding rotor when the grinder is turned on, for example in the event of a software malfunction.

[0008] Referring again to the example of a cutting grinder, the grinding chamber is usually closed by a door at the end. The door can be electronically monitored and locked electronically, for example, to protect the user. Such a grinder can have, for example, an electrical locking device, so that the door cannot be opened during operation of the grinder. Knife grinders usually have a correspondingly fixed cover, for example in the form of an appliance hood, which, in the closed state, prevents access to the interior of the grinding container in which the rotor knives are arranged.

[0009] For such electrical or electronic safety systems, due to safety requirements, dual-channel or redundant circuits as well as various redundant standstill monitoring are required in order to avoid residual risks in the event of electrical faults.

[0010] The grinding machine can also have a motor brake, which can be flanged, for example, on the back side of the motor shaft in order to be able to brake the motor shaft more quickly. For safety reasons, the motor brake brakes in the de-energized state, and in order to operate the grinding machine, the brake shoe is actively disengaged from the motor shaft by energizing it. However, the motor brake is subject to high wear and generally does not provide monitoring as to whether it is functioning properly. In addition, such a motor brake constantly requires electrical energy during operation in order to remain disengaged. Furthermore, the brake is generally not a safety-oriented component in the sense of DIN EN ISO 12100, so that additional electrical safety measures are required.

[0011] DIN EN ISO 12100 - "Machine safety" contains general machine-specific design guidelines for risk assessment and risk reduction and is also important for CE approval of laboratory equipment. According to DIN EN ISO 12100, the term "machine safety" means the ability of a machine to fulfil its intended function throughout its entire service life without incurring intolerably high risks.

[0012] In order to meet the safety requirements of DIN EN ISO 12100, for example, cutting and grinding machines usually have several electrical safety-oriented components as follows:

[0013] 1.Safety door contact,

[0014] 2. Safe door locking device,

[0015] 3. Reliable feedback from the door locking device to the control device of the cutting and grinding machine,

[0016] 4. Various redundant and safe stop detection for drive devices,

[0017] 5. Safe torque cut-off of the drive unit,

[0018] 6. Reliable status feedback from each safety circuit and signal device to the control device of the cutting and grinding machine,

[0019] Here, "safety" is understood in the sense of DIN EN ISO 12100.

[0020] Laboratory grinding machines with electrical or electronic safety devices or motor brakes, although proven in principle, can be cost-intensive and require further improvement with regard to potential for error. Summary of the invention

[0021] The object of the present invention is to provide a laboratory grinding machine which meets high safety standards, in particular with regard to user intervention in the grinding machine.

[0022] Another object of the present invention is to provide a laboratory grinder which is simple, inexpensive and not prone to malfunction.

[0023] Another object of the invention is to provide a laboratory grinder having a cost-effective, non-fail-resistant safety device against undesired user intervention in the grinder, which safety device is compact and can also be integrated into simple and compact laboratory grinders.

[0024] A further object of the present invention is to provide a laboratory grinder which is safe, in particular in the sense of DIN EN ISO 12100, and which avoids or at least reduces the above-mentioned disadvantages.

[0025] The object of the invention is achieved by the subject matter of the independent claims. Advantageous developments of the invention are defined in the dependent claims.

[0026] A laboratory grinder for comminuting grinding material is provided, which has an apparatus housing with a grinder housing and / or a grinding container. The grinder housing or the grinding container defines a grinding chamber in the grinder housing or the grinding container, in which a particularly rotating grinder is arranged or inserted, which grinds the grinding material when the grinder is in operation. The grinder housing or the grinding container has a particularly axial user access opening, through which a user has access to the grinder in the open state.

[0027] The user access opening can be closed by a grinder housing door or a safety cover, so that the grinder housing door or the safety cover defines an open and closed state, and the user can access the grinder through the user access opening in the open state of the grinder housing door or the safety cover, and the grinder is encapsulated in an intrusion-proof manner in the closed state to operate the laboratory grinder, so that the user cannot safely access the grinder during operation.

[0028] The grinding machine is in particular designed as a rotor grinding machine. The laboratory grinder also has a motor-grinding drive for the rotational drive of the grinding machine, for example via an electric motor and a drive shaft.

[0029] The grinding machine housing door or the safety cover has a closure element, by means of which the grinding machine housing door or the safety cover is mechanically locked in the closed state in order to operate the laboratory grinder safely.

[0030] The laboratory grinding machine advantageously has a mechanical grinder drive lock, with which the grinder drive can be mechanically locked. The grinder drive lock is in particular mechanically actuated directly or indirectly by the closure element.

[0031] The laboratory grinder can be configured in particular as a cutting grinder, an impact cross grinder, a disc grinder, a knife grinder or a punch grinder. In a cutting grinder, an impact cross grinder or a disc grinder, preferably, there is a possibly solid grinder housing around the rotor grinder, and the grinder housing is closed by a grinder housing door. In this case, the closing element for the grinder housing door can also be referred to as a door closure. A knife grinder or a punch grinder can have a grinding container, for example, made of (transparent) plastic or stainless steel, in which a grinding rotor, for example a rotor knife or an impact rotor, is arranged rotating around a vertical axis. Knife grinders and punch grinders can also (but not necessarily) additionally have a housing with a closure cover around the grinding container. In a knife grinder or a punch grinder with an additional housing, the safety cover can be configured as a closure cover, and the closure element can be mounted on the safety cover configured as a closure cover and lock it in a closed state. In knife grinders or punch grinders without an additional closed enclosure, there is at least a safety cover that reliably closes the grinding container upwards. In this case, a closure element can also be mounted on the safety cover and lock it in the closed state, thereby closing the grinding container in an tamper-proof manner.

[0032] When the grinder housing door or the safety cover is not locked, the grinder drive locking device mechanically locks the grinder drive device in a form-fitting manner, and when the grinder housing door or the safety cover is locked, the grinder drive device is released. When the grinder housing door or the safety cover is closed, the closure element and the grinder drive locking device can be connected to each other by a mechanical operating chain for this purpose. On the other hand, when the grinder housing door or the safety cover is opened, the mechanical operating chain can be interrupted. In other words, through the closed mechanical operating chain, when unlocking and locking the grinder housing door or the safety cover, the movement of the closure element can be mechanically transmitted to the grinder drive locking device to lock or unlock the grinder drive locking device.

[0033] Laboratory grinders can be configured, for example, as laboratory-scale cutting grinders, impact cross grinders, disc grinders, knife grinders or punch grinders. In cutting grinders or impact cross grinders, the grinder has one or more fixed cutting pieces and a coaxial cutting rotor that preferably rotates around a horizontal axis in the fixed cutting piece. Cutting grinders work according to the shearing principle, wherein the grinding material is crushed in a cutting manner between the cutting piece and the mating cutting piece of the cutting rotor. The structure of the impact cross grinder is similar, but has a larger gap size between the cutting piece and the mating cutting piece. In a disc grinder, a rotor grinder has an axially opposite rotating disk and a fixed disk, and the grinding material is crushed in the gap extending laterally between the two disks. In a punch grinder, the impact rotor rotates around a preferably vertical axis, for example in an annular screen, and the grinding material is crushed by the impact action of the impact rotor teeth. The rotor grinder and the annular screen can be arranged in a grinding container, which is inserted into a surrounding shell. In a knife grinder, the rotor knife without a counter-cutting element rotates in the grinding container about a vertical axis. An additional enclosure around the grinding container is possible, but not mandatory.

[0034] In particular, the laboratory grinder has such dimensions that it can be placed in a typical laboratory, for example on a laboratory table or on feet on the laboratory floor.

[0035] The axial user access opening is preferably used to allow the user to access the grinding chamber axially via the user access opening when the grinding machine housing door or the closure cover is open, for example to remove the grinding material or the grinding rotor from the grinding chamber or to clean the grinding chamber or to replace or clean the screen. For this purpose, the grinding rotor can be plugged onto the drive shaft preferably using form-fitting elements and can be axially screwed or latched, if necessary, and can be manually removed after the screwing or latching has been released, if necessary.

[0036] For cutting mills, the diameter and / or length of the laboratory mill (cutting) rotor can be, for example, in the range of a few millimeters, for example, from 20 mm to about 15 cm or about a maximum of 20 cm. In a disc mill, the diameter can be larger if necessary, for example 15 cm to 30 cm.

[0037] In order to be able to feed the grinding material to the grinding machine when the laboratory grinder is in operation and the grinding machine housing door or the safety cover is closed, the grinding machine housing or the safety cover can also have an axial or radial grinding material feed opening, for example a feed funnel, through which the grinding material can be axially or radially introduced into the grinding chamber in order to continuously comminute the grinding material by the grinding machine, for example between the grinding rotor and one or more fixed counter elements or by means of rotor knives or impact rotors. In cutting mills, the grinding material feed opening is in particular radial, and in impact cross mills, disc mills, knife mills or punch mills, it is in particular axial.

[0038] Advantageously, a high user safety can be ensured by means of a mechanical grinder drive locking device, which mechanically locks the grinder drive device in a form-fitting manner. For example, this reliably prevents the grinder rotor (e.g., a cutting rotor), a rotating disk, a rotor knife, or an impact rotor from rotating when the grinder housing door or a safety cover is opened. In addition, possible failures of the electronic safety device cannot impair the safety of the laboratory grinder against accidental opening of the grinding chamber. In addition, unintentional or even intentional misoperation can be effectively avoided. The form-fitting locking of the mechanical operation of the grinder drive device also prevents impermissible manipulation above average and generally provides high safety to prevent vulnerable misoperation or unforeseen events. In particular, multiple redundant electronic safety devices, safety contacts, safety locking devices, or electrical status feedback to the control device can be at least partially omitted, for example. Nevertheless, the safety of the laboratory device in the sense of DIN EN ISO 12100 or required for obtaining the CE mark can be met.

[0039] The grinding machine drive can include a drive motor, in particular an electric motor, and a drive shaft, which is connected to the grinding machine in order to drive the grinding machine in rotation. When the grinding machine housing door or the safety cover is not locked, a mechanical grinding machine drive locking device can act on the drive shaft and mechanically lock the rotation of the drive shaft in a form-fitting manner. Here, the grinding machine drive locking device can preferably be arranged between the drive motor and the grinding machine rotor. The direct form-fitting locking of the drive shaft ensures high safety, for example, prevents electrical functional failures in the grinding machine drive.

[0040] According to one embodiment, the mechanical grinding machine drive locking device has a positive-locking, in particular axial positive-locking coupling element, which in the disengaged state releases the grinding machine drive for rotation and in the engaged state positively locks the grinding machine drive.

[0041] The axially positive coupling can have a stator coupling part connected to the device housing and a rotor coupling part connected to the grinding machine drive and / or a rotating part of the grinding machine. In the positively engaged state of the stator coupling part and the rotor coupling part, the coupling part positively locks the rotation of the grinding machine drive and / or the grinding machine.

[0042] Preferably, the coupling piece of form fit is directly or indirectly mechanically manipulated by closure element, for example by mechanical operating chain.For example in rotatable closure element, the rotational motion of closure element can be converted into the movement of mechanically causing the engagement and separation of the coupling piece of form fit.

[0043] The engagement and disengagement of the form-fitting coupling can be achieved, for example, by an axial displacement of the stator coupling part and / or the rotor coupling part. The stator coupling part and the rotor coupling part can have complementary teeth, which mesh with each other in a form-fitting manner, in particular axially, when the form-fitting coupling parts are engaged, in order to form-fit lock the rotation of the grinding machine. The teeth can preferably taper in the direction of the complementary other coupling part to facilitate the engagement. This can largely prevent the engagement from being impossible in a tooth-to-tooth position of the teeth.

[0044] When the closing element moves for opening, in particular, the mechanical grinder drive locking device is first locked, or the form-fitting coupling is first engaged, and only after the mechanical grinder drive locking device has been locked or the form-fitting coupling has been engaged and the grinder drive is locked in a form-fitting manner, can the closing element be mechanically opened until the unlocking of the grinder housing door or the safety cover. In other words, as long as the mechanical grinder drive locking device is not locked or the form-fitting coupling is not engaged, the unlocking of the grinder housing door or the safety cover is mechanically locked, and the grinder housing door or the safety cover cannot be unlocked. When the closing element moves for closing, the grinder housing door or the safety cover is first locked, and only after the grinder housing door or the safety cover is locked, when the closing element is further closed, the mechanical grinder drive locking device is unlocked or the form-fitting coupling is separated, and the grinder drive is released for rotation. Therefore, at least as long as the closing element is not locked, the grinder drive locking device cannot be mechanically unlocked or the form-fitting coupling cannot be separated. Therefore, the opening of the closure element is carried out in two stages of the movement of the closure element. In the first stage, the closure element firstly operates the locking of the grinding machine drive locking device via a mechanical operating chain, and then in the second stage, the closure element unlocks the grinding machine housing door or the safety cover. The closing of the closure element is also carried out in two stages of the movement of the closure element. In the first stage, the closure element firstly locks the grinding machine housing door or the safety cover, and then in the second stage, the closure element operates the unlocking of the grinding machine drive locking device via a mechanical operating chain.

[0045] The movement of the closure element during closing therefore takes place in particular in temporally successive movement phases:

[0046] 1. Locking the grinding machine housing door or the safety cover by a closing movement, for example a rotation of the closure element in the closing direction, wherein the grinding machine drive locking device remains locked,

[0047] 2. Unlocking the grinding machine drive locking device during a continued closing movement, for example a rotation of the closure element in the closing direction, wherein the closure element keeps the grinding machine housing door or the safety cover locked.

[0048] The movement of the closure element during opening takes place in particular in temporally successive movement phases:

[0049] 1. Locking the grinding machine drive locking device by an opening movement, for example by turning a closing element, wherein the closing element keeps the grinding machine housing door or a safety cover locked,

[0050] 2. Unlocking the grinding machine housing door or the safety cover during a continued opening movement, for example a rotation of the closure element, wherein the grinding machine drive locking device remains locked.

[0051] In other words, a laboratory grinder has four states:

[0052] 1. The grinder housing door or safety cover is open and the grinder drive lock is locked, allowing the user to safely access the grinder.

[0053] 2. The grinder housing door or safety cover is closed but not locked, wherein the grinder drive locking device is locked.

[0054] 3. The grinding machine housing door or the safety cover is closed and locked, but the closure element has not yet moved to the stop, wherein the grinding machine drive locking device is locked.

[0055] 4. The grinding machine housing door or the safety cover is closed and locked, and the closure element is moved to the stop, wherein the grinding machine drive locking device is unlocked.

[0056] To start operation, the user operates the laboratory grinder as follows, starting from the open state of the grinder housing or the safety cover and the locked state of the grinder drive lock:

[0057] 1. The user closes the grinder housing door or safety cover, wherein the grinder drive locking device is locked.

[0058] 2. The user moves the closure element in the closing direction and thereby first locks the grinding machine housing door or the safety cover, wherein the grinding machine drive locking device remains locked.

[0059] 3. The user moves the closure element further in the closing direction to the stop, thereby operating the grinding machine to drive the locking device to unlock.

[0060] For opening, the user actuates the laboratory grinder starting from the closed state of the grinder housing or the safety cover and the unlocked state of the grinder drive lock as follows:

[0061] 1. The user moves the closure element from the stop in the opening direction, thereby first actuating the grinding machine drive locking device to lock.

[0062] 2. The user moves the closure element further in the opening direction and thereby unlocks the grinding machine housing door or the safety cover, wherein the previously locked grinding machine drive locking device remains locked.

[0063] 3. The user opens the grinding machine housing door or the safety cover in order to gain access to the grinding machine, wherein the grinding machine drive locking device remains locked.

[0064] This ensures that the grinding machine drive is mechanically locked and no longer able to rotate by inertia at the moment the grinding machine housing door or safety cover is unlocked and thus before the grinding machine housing door or safety cover can be opened. In addition, when the grinding machine housing door or safety cover is open, for example, starting can be reliably prevented in the event of an electronic malfunction, which ensures a high safety standard.

[0065] Preferably, the form-fitting coupling has a stator coupling ring and a rotor coupling ring arranged around the drive shaft. The stator coupling ring can be fixed to the device housing in a substantially rotationally fixed manner with a certain angular play, and the drive shaft can rotate in the stator coupling ring. The rotor coupling ring can be fixed to the drive shaft in a substantially rotationally fixed manner.

[0066] The positive-fit coupling is preferably engageable in any rotational position of the grinding rotor, in particular without starting the drive motor. This can be achieved, for example, in that at least one of the coupling parts meshing in a positive manner has at least enough play relative to the other coupling part that the coupling can engage in a positive manner, for example, the teeth of the coupling can engage in a positive manner, even if the grinding rotor is stuck, for example, by the grinding material. Preferably, there is play on both sides, so that the coupling can fully engage in any rotational position of the grinding rotor and the grinding machine housing door can be opened. For this purpose, for example, in the case of an axial positive-fit coupling, it is advantageous if the coupling has a plurality of teeth and / or if the axial positive-fit coupling or at least one of the two coupling rings has a slight angular play in both rotational directions, i.e., at least enough play that the teeth of the coupling can still fully engage in any rotational position of the grinding rotor even in a completely stuck grinding rotor. The play or angular play on both sides is preferably balanced in the middle in the disconnected state of the coupling.

[0067] By axially moving the stator coupling ring and / or the rotor coupling ring, the form-fitting coupling can be engaged and disengaged to lock and release the grinding machine drive locking device.

[0068] According to an exemplary embodiment, the form-fitting coupling may have an axial pressure plate which is actuated to move axially by the movement of the closing element when the closing element moves in the opening direction in order to form-fittingly couple the stator coupling ring and the rotor coupling ring to each other.

[0069] As part of the mechanical control chain, a mechanical control device may be included, to which the closing element is coupled when the grinder housing door or the safety cover is closed, and which mechanically transmits the movement of the closing element to the grinder drive locking device when locking and unlocking the grinder housing door or the safety cover, so as to unlock or lock the grinder drive locking device. The mechanical control device can thus form a mechanical connection between the closing element and the grinder drive locking device in the mechanical control chain, so that the mechanical control of the grinder drive locking device is carried out indirectly via the mechanical control device through the closing element.

[0070] According to one embodiment, the mechanical actuation device also allows the stator coupling to have such a degree of rotational play that, for example, if the grinding machine is jammed by the grinding material in the grinding machine housing, the teeth of the stator coupling and the rotor coupling can nevertheless engage due to the rotational play. Alternatively or additionally, the rotor coupling can also have such a small degree of rotational play relative to the drive shaft. This makes it possible to facilitate the engagement of the positive coupling while maintaining the safety features. As described above, the engagement can also be simplified by tapering teeth, for example with a triangular cross section.

[0071] In order to couple when the grinding machine housing door or safety cover is closed, the closing element and the mechanical operating device can have mutually complementary coupling elements, which are coupled to each other when the grinding machine housing door or safety cover is closed and are disengaged from each other when the grinding machine housing door or safety cover is opened, so that in the coupled state, when the grinding machine housing door or safety cover is closed, the movement of the closing element is mechanically transmitted to the grinding machine drive locking device via the coupled coupling element and the mechanical operating device, so that when the closing element is closed, the grinding machine drive locking device is released, and when the closing element is opened, the grinding machine drive locking device is locked and the grinding machine drive device is locked. For example, complementary dihedrals or polygons that are axially meshed in a form-fitting manner when the grinding machine housing door or safety cover is closed have proven to be advantageous as complementary coupling elements. Dihedrals also have the advantage that they can only be coupled in two orientations rotated by 180°.

[0072] The closure element can be designed, for example, as a key with a rotating handle, which engages in a closure sleeve on the grinding machine housing, wherein the grinding machine housing door or the safety cover is locked in the closure sleeve by turning the key. For example, the key can include two transverse locking bolts, which engage in complementary closure sleeves and lock in the closure sleeves when turned (key lock principle). It is advantageous here that the locking is already achieved at a small rotation angle of the key, and the separation of the form-fitting coupling only begins when the key is further rotated when closing the grinding machine housing door or the safety cover, that is, in the case of continued key rotation, the separation of the form-fitting coupling only begins after the key has locked.

[0073] Therefore, when the grinding machine housing door or safety cover is closed, the key can form a mechanical operating chain with the grinding machine drive locking device through the coupled coupling element and the mechanical operating device, so that the rotation of the key causes the locking and unlocking of the grinding machine drive locking device through the coupled, for example, dihedral coupling element and the mechanical operating device.

[0074] In this way, in cooperation with the drive locking device, a simple and cost-effective, but nevertheless reliable locking of a grinding machine housing door or a safety cover can be achieved.

[0075] According to one embodiment, the mechanical actuation device can have a transverse slide, for example a transverse slide plate, wherein the actuation, for example a rotation of the closing element, leads to a transverse displacement of the slide plate relative to the drive shaft. The mechanical actuation device can thus be compactly integrated into the drive concept of the laboratory grinder and the mechanism for causing the drive lock can nevertheless be designed in a stable and therefore safe manner.

[0076] According to one embodiment, the mechanical operating device may include an operating shaft and an eccentric wheel. The operating shaft may have one of two complementary coupling elements, so that when the grinding machine housing door or the safety cover is closed and / or the closing element or the key is inserted into the closing sleeve, the closing element or the key (including the other of the two complementary coupling elements) is detachably coupled to the operating shaft. In the coupled state of the complementary coupling elements, the operating shaft can be rotated by the rotation of the closing element or the key, and the eccentric wheel converts the rotational movement into a lateral movement of the sliding plate.

[0077] In addition, the mechanical operating device can have at least one wedge element, which converts a lateral movement of the sliding plate, for example via an axially movable pressure plate of a form-fitting coupling part, into an axial movement of the form-fitting coupling part, i.e. an axial movement of the stator coupling part or stator coupling ring and / or a rotor coupling part or rotor coupling ring.

[0078] The important safety of the laboratory grinder can be achieved by mechanically locking the grinder drive in a form-fitting manner. However, additional electrical or electronic protective measures can also be provided. For example, a control device and a holding device in the form of an electromagnet that can be electrically activated can be included. When the laboratory grinder is running, the control device activates the holding device, and the activated holding device magnetically holds the operating device, such as a sliding plate. As long as the grinder drive is still rotating, the movement of the closing element can be prevented by magnetically attached holding. The control device can query the rotation of the grinder drive or wait for a predetermined idling delay time, and only when the control device detects that the grinder drive is no longer rotating or the idling delay time is over, the control device deactivates the holding device. This can prevent the user from trying to unlock the closing element when the coupling is still rotating relative to each other, and thus engage the form-fitting coupling. Although as long as the form-fitting coupling is not engaged, the closing element cannot be completely unlocked mechanically by a mechanical operating chain, the use of the holding device can avoid the undesirable wear caused by erroneous operation on the form-fitting coupling. However, it is not necessary to design this additional electronic control protection function with safety redundancy, but this should not be excluded.

[0079] When opening the closure element, the movement of the closure element is transmitted to the grinding machine drive locking device by a mechanically rigid coupling or forced guidance through a mechanical operating device, so as to reliably lock the grinding machine drive locking device by engaging a form-fitting coupling. The movement of the closure element when closing the closure element is also transmitted to the grinding machine drive locking device through a mechanical operating device, unlocking the grinding machine drive locking device and releasing the form-fitting coupling for separation, wherein the separation of the form-fitting coupling can be caused by one or more spring elements. In other words, the engagement of the form-fitting coupling can be carried out against the spring tensioning force. However, separation by forced guidance is not excluded.

[0080] According to one aspect of the present invention, there is provided a laboratory grinder in the form of a cutting grinder, an impact cross grinder, or a disc grinder for crushing a grinding material, comprising:

[0081] A device housing having a grinding machine housing,

[0082] a grinding chamber in a grinder housing, wherein a grinder is arranged in the grinding chamber, by means of which the grinding material is comminuted, and wherein the grinder housing has a user access opening,

[0083] A grinding machine housing door for closing a user access opening, wherein the grinding machine housing door has an open state and a closed state, wherein a user can access the grinding machine through the user access opening in the open state of the grinding machine housing door,

[0084] A grinding machine drive for driving a grinding machine,

[0085] The grinding machine housing door has a door lock, by which the grinding machine housing door can be locked in a closed state, and

[0086] The laboratory grinder has a mechanical grinder drive lock.

[0087] According to another aspect of the present invention, there is provided a laboratory grinder in the form of a knife grinder or a punch grinder for comminuting a grinding material, comprising:

[0088] Equipment housing and grinding container,

[0089] A grinding chamber in a grinding container, wherein a rotor grinder having a grinding rotor (for example a rotor blade or an impact rotor) which rotates, in particular about a vertical axis, can be arranged in the grinding chamber, by means of which the grinding material is comminuted, and

[0090] The grinding container has a user access opening, in particular an upper part of the grinding container which is open upwards,

[0091] A safety cover, wherein the safety cover has an open state and a closed state, wherein the safety cover in the open state allows a user to access the opening, in particular to access the grinding machine rotor from above;

[0092] A grinding machine drive for driving a grinding machine rotor,

[0093] The safety cover has a closure element, by which the safety cover can be locked in the closed state, and

[0094] Among them, the laboratory grinder has a mechanical grinder drive lock. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] The present invention will be described in detail below with the aid of exemplary embodiments and with reference to the accompanying drawings, wherein identical and similar elements are partly provided with identical reference numerals, and features of different exemplary embodiments may be combined with one another.

[0096] Figure 1 shows a three-dimensional view of a cutting grinder according to one embodiment of the present invention,

[0097] Figure 2 Shows Figure 1 A cutting grinder with a grinder housing shown transparently,

[0098] Figure 3 Shows Figure 1 A cutting grinder with an open grinder housing door,

[0099] Figure 4 Shown in slightly opened state Figure 1 A partially transparent 3D view of the grinder housing door and door lock of a cutting grinder,

[0100] Figure 5 Shown in slightly opened state Figure 1 Partially transparent 3D view of the grinder housing of a cutting grinder, viewed from the motor side,

[0101] Figure 6 Shows the closed state Figure 1 A partially transparent 3D view of the grinder housing of a cutting grinder,

[0102] Figure 7 A partially transparent three-dimensional view of the actuating device is shown in the engaged state of the form-fitting coupling and in the closed but unlocked state of the grinding machine housing door,

[0103] Figure 8 Shows Figure 7 A partial enlarged view of area A in

[0104] Fig. 9Shows Figure 7 A partial enlarged view of area B in FIG.

[0105] Fig.10 shows a three-dimensional view of the actuating device and the form-fitting coupling in the engaged state,

[0106] Fig.11 shows an axial view from the rear of the actuating device in the engaged state of the form-fitting coupling,

[0107] Fig.12 A partially transparent three-dimensional view of the actuating device is shown with the grinding machine housing door closed and locked and in the disengaged state of the form-fitting coupling,

[0108] Fig.13 Shows Fig.12 A partial enlarged view of area A in

[0109] Fig.14 Shows Fig.12 A partial enlarged view of area B in FIG.

[0110] Fig.15 shows a three-dimensional view of the actuating device and the form-fitting coupling in the separated state,

[0111] Fig.16 shows an axial view from the rear of the actuating device in the disengaged state of the form-fitting coupling,

[0112] Fig.17 Shows Figure 1 Longitudinal section of a cutting and grinding machine,

[0113] Fig.18 A three-dimensional view of a knife grinder with a half-open safety cover according to another embodiment of the present invention is shown,

[0114] Fig.19 Shows Fig.18 A partial enlarged view of area A in

[0115] Fig. 20 like Fig.19 , but the safety cover is almost closed,

[0116] Fig.21 Shows Fig.18 A partially cutaway 3D view of a knife grinder with a closed safety cover,

[0117] Fig. 22 Shows Fig.21 A partial enlarged view of area A in

[0118] Fig.23A three-dimensional view of a knife grinder with a half-open safety cover according to another embodiment of the present invention is shown,

[0119] Fig.24 Shows Fig.23 A partial enlarged view of area A in

[0120] Fig.25 like Fig.23 , but the safety cover is closed,

[0121] Fig.26 Shows Fig.25 A partial enlarged view of area A in

[0122] Fig. 27 like Fig.25 , but the parts are hidden,

[0123] Fig.28 Shows Fig. 27 A partial enlarged view of area A in

[0124] Fig.29 Shows Figure 1 Partially transparent rearward 3D view of a cutting grinder. DETAILED DESCRIPTION

[0125] Reference Figure 1-17 29, a laboratory grinder 1 is shown, in the present example in the form of a cutting grinder. The laboratory grinder 1 has an apparatus housing 12 with a user display 14 for the user to input grinding parameters into a control device (not shown) of the laboratory grinder 1. A grinder housing 16 is arranged on the front side 12a of the apparatus housing 12, which can be closed at the front (axially) by means of a safety cover in the form of a grinder housing door 18. The grinder housing door 18 is designed as a swing door and can be swung open and closed about a hinge 20. When the grinder housing door 18 is opened, the grinder housing door 16 is opened. Figure 1 When shown closed, the grinder housing door 18 can be locked with a closure element 22 in the form of a door lock 22'. Only when the closure element 22 is completely unlocked can the user pivot the grinder housing door 18 open in order to gain access to the rotor grinder 84 in the interior or grinding chamber 82 of the grinder housing 16. When the grinder housing 16 is closed, the grinding material can be introduced through the charging funnel 24 and the radial grinding material charging opening 25 in this example, so that the grinding material can be continuously conveyed and comminuted during operation of the cutting grinder.

[0126] The closure element 22 comprises, for example, a rotary handle 23 or a knob and a locking bolt 26 to form a key 28. The closure element 22 or the key 28 is rotatably arranged in the grinder door 18 and can be inserted into a closure sleeve 30 on the front side 16a of the grinder housing 16 in a suitable rotational position. Due to the transverse extension of the locking bolt 26, the closure element 22 can only be locked when it is in the position of the front side 16a of the grinder housing 16. Figure 3-4 , the closure element 22 can only be inserted into the closure sleeve 30 when the closure element 22 is in the unlocked rotational position shown in FIG. In the present example, the closure sleeve 30 is formed as a kind of keyhole, and when the locking bolt or transverse bolt 26 is vertical, the closure element 22 or the key 28 can engage in the closure sleeve 30. The closure sleeve 30 has a transverse groove 31 in the manner of a keyhole, into which the locking bolt or transverse bolt 26 is inserted according to the key-keyhole principle when the key 28 is inserted into the closure sleeve 30. By subsequently rotating the closure element 22 with the transverse bolt 26 out of the vertical direction, the transverse bolt 26 is locked in the closure sleeve 30 and the grinding machine housing door 18 is thus locked.

[0127] The closure element 22 has a positive-fit coupling element 34 at the coupling end 32. When the coupling end 32 is inserted into the closure sleeve 30, a positive-fit connection is formed between the coupling element 34 and the complementary coupling element 36 of the operating shaft 38, so that a positive-fit connection is established between the closure element 22 and the operating shaft 38. In the present embodiment, the operating shaft 38 is rotatably supported in the closure sleeve 30, and the two complementary positive-fit coupling elements 34, 36 are respectively formed in the form of complementary dihedrals 35, 37. When the grinding machine housing door 18 is closed and the closure element 22 is inserted into the closure sleeve 30, the two dihedrals 35, 37 engage with each other in a positive-fit manner. When the closure element 22 is subsequently rotated to lock in the closure sleeve 30 when the grinding machine housing door 18 is closed, the closure element 22 rotates the operating shaft 38 by coupling the two dihedrals 35, 37. The eccentric disk 40 is fixed in a defined angular position at the end 38 b of the actuating shaft 38 opposite the coupling element 36 in a form-fitting manner, for example by being screwed together in a defined angular position with a form-fitting connection between the actuating shaft 38 and the eccentric disk 40 .

[0128] The closure element 22, the closure sleeve 30 and the coupling elements 34, 36 are rotationally positioned clearly relative to one another by means of the engagement of the coupling elements 34, 36 when the actuating chain 65 is closed, wherein in the present example two rotational positions of the closure element 22 are possible. In other words, the transverse groove 31 is oriented such that in the same rotational position of the closure element 22, the two coupling elements 34, 36 also axially engage with one another in this rotational position of the closure element 22 in which the locking bolt 26 of the closure element 22 engages in the transverse groove 31. Furthermore, the closure element 22 can only be locked when the closure element 22 has been introduced into the closure sleeve 30 to such an extent that the two coupling elements 34, 36 have been coupled to one another or the actuating chain 65 has been closed.

[0129] refer to Figure 5-16 , the eccentric disk 40 is guided in the opening 42 of the transverse sliding plate 44. When the closing element 22 is manually rotated by the user, the closing element transmits the rotational movement of the closing element 22 to the operating shaft 38 via the coupling elements 34, 36. As a result, the operating shaft 38 rotates the eccentric disk 40 in the rectangular opening 42. The sliding plate 44 is guided transversely by the linear guide 46, so that the sliding plate 44 is driven by the eccentric disk 40, in this example, horizontally moved, more precisely, initially driven by the manual operation of the closing element 22, in this example, by the rotation of the closing element 22. Therefore, by the arrangement of the eccentric disk 40 in the opening 42, the rotational movement of the closing element 22 or the operating shaft 38 is converted into a transverse translational movement of the sliding plate 44. The locking of the closing element 22 or the grinding machine housing door 18 thus simultaneously causes a rotation of the operating shaft 38 and the eccentric 40, and thus causes a transverse movement of the sliding plate 44.

[0130] A wedge drive 48 with a ramp or lifting wedge 50 is arranged on the sliding plate 44. During the lateral movement of the sliding plate 44, the cylindrical pin 52 of the pressure plate 54 slides on the lifting wedge 50, thereby converting the linear lateral movement of the sliding plate 44 into an axial movement of the pressure plate 54 relative to the axis of rotation X of the laboratory grinder. A stator coupling part 56 in the form of a stator coupling ring 57 is fixed to the pressure plate 54, which is axially moved by the pressure plate 54. A rotor coupling part 58 in the form of a rotor coupling ring 59 is arranged axially opposite the stator coupling part 56. The two coupling parts or coupling halves 56, 58 have a positive-fitting toothing element 62 in the form of complementary teeth 68 and form a positive-fit coupling part 60. When the stator coupling part 56 is moved axially relative to the rotor coupling part 58 by means of the pressure plate 54 and the complementary teeth 68 of the two coupling parts 56, 58 axially form a positive fit, the coupling part 60 engages.

[0131] The drive shaft 2 of the drive motor 4 ( Fig.17) extends coaxially through the two coupling rings 57, 59 and defines the drive axis X. Here, the rotor coupling ring 59 is fixed to the drive shaft by means of a form fit, i.e. rotates with the drive shaft. The stator coupling ring 57 is fixed to the device housing 12 by means of a pressure plate 54 in a cutout 64 of the sliding plate 44, allowing a certain angular clearance. When the stator coupling ring 57 is axially moved toward the rotor coupling ring 59, a form-fitting connection is formed, which form-fits and locks the drive shaft to prevent rotation. Therefore, the two coupling parts 56, 58 form the coupling halves of a form-fitting coupling 60, which, when the coupling 60 is engaged, form-fits and locks the rotation of the drive shaft.

[0132] The mechanical actuation for engaging the coupling 60 is accordingly effected by a mechanical actuation chain 65, by a rotation of the closure element 22, which is connected to the actuation shaft 38 via the coupling elements 34, 36 when the closure element 22 is inserted into the closure sleeve 30, and further by an eccentric disk 40 and a wedge drive 48 with a lifting wedge 50 and a pin 52, in order to engage and disengage the coupling 60, by a rotation of the closure element 22, and further by an eccentric disk 40 and a wedge drive 48 with a lifting wedge 50 and a pin 52, in order to engage and disengage the coupling 60. In other words, the actuation shaft 38, the eccentric disk 40, the sliding plate 44, the wedge drive 48, the lifting wedge 50 and the pressure plate 54 together with the pin 52 form an example of a mechanical actuation device 66, by means of which a rotational movement of the closure element 22 is mechanically transmitted to the positive coupling 60, in order to engage and disengage the coupling.

[0133] Generally speaking, the rotation of the closure element 22 is converted into an axial movement when the closure element is unlocked and locked, by means of which the coupling parts 56 , 58 or the coupling piece 60 are axially engaged and disengaged.

[0134] In the engaged state of the form-fitting coupling 60, the rotation of the drive shaft is prevented in the following manner, that is, the pressure plate 54 is located in the rectangular cutout 64 of the sliding plate 44 and is held in a form-fitting manner. However, when the form-fitting coupling 60 is engaged, the pressure plate 54 has a small angular clearance around the drive shaft 2 in the cutout 64 by the bevel 55 in this example. As a result, when the form-fitting coupling 60 is engaged, the mutual engagement of the complementary teeth 68 can be facilitated, because it can be prevented that the teeth 68 are opposite to each other in the tooth-to-tooth position and cannot be engaged as a result. In addition, the teeth 68 taper gradually in the direction of the corresponding opposite coupling rings to further improve the engagement. In this example, the teeth 68 have a triangular cross section.

[0135] In order to allow the pressure plate 54 to enter the initial position of the positive-fit coupling 60 being released or the drive shaft being unlocked again when the closure element 22 is locked, i.e. when the sliding plate 44 is pulled back, the pressure plate 54 is guided by two spring pressure pieces 70, whose spring-loaded balls are embedded in the conical holes. The pressure pieces 70 cause the pressure plate 54 to be elastically reset into the released state of the positive-fit coupling 60. Nevertheless, the pressure pieces 70 allow a slight angular rotation around the drive shaft in order to allow the positive-fit coupling 60 to engage even when the grinding rotor 86 is stuck. The spring pressure pieces 70 are used to equalize the angular play of the pressure plate 54 in the released state in a central manner, so that the pressure plate 54 or, more generally, the positive-fit coupling 60 has sufficient angular play in both rotational directions, so that the positive-fit coupling 60 can engage in any rotational position of the drive shaft, even when the grinding rotor 86 is stuck.

[0136] When the laboratory grinder 1 is in operation, the closure element 22 is locked, the positive coupling 60 is disengaged and the sliding plate 44 is in the position according to Figure 12-16 In this state of locked closure element 22 and unlocked grinding machine drive, the sliding plate 44 is magnetically fixed by the electromagnet 72 .

[0137] The maximum idle delay time of the drive is stored in the control device (not shown) of the laboratory grinder 1, which is usually placed in the device housing 12, and the control device deactivates a holding device, for example in the form of an electromagnet 72, after waiting for the maximum idle delay time, thereby releasing the movement of the mechanical control chain 65, so that the closing element 22 can be unlocked. Waiting for the maximum idle delay time ensures that the drive has stopped when the holding device is deactivated. This can save the technically complex electrical shutdown monitoring of the drive. As long as the drive shaft rotates, the control device keeps the electromagnet 72 activated so that the electromagnet fixes the sliding plate 44 to prevent the user from trying to open the grinding machine housing cover 18 when the drive shaft rotates. Although as long as the form-fitting coupling 60 is not engaged, the unlocking of the closing element 22 from the closing sleeve 30 is always mechanically locked. However, the magnetic fixation can prevent the user from trying to engage the form-fitting coupling 60 when rotating. Undesirable wear due to incorrect operation can thus be avoided.

[0138] Furthermore, the rotational position of the eccentric 40 and thus the position of the slide plate 44 or the mechanical actuating device 66 can be queried by means of an electric motor start-up blocking device, for example by means of a sensor or a switch 73. However, the switch does not need to be a safety switch, since due to the mechanical blocking of the drive device no harm can occur even in the event of a switch failure. However, the use of a safety switch is not excluded. The same applies to magnetic fixing by means of an electromagnet 72. The control device of the laboratory grinder 1 receives a release signal from the electric motor start-up blocking device, which release signal allows the user to start the drive motor 4. This prevents the user from attempting to start the drive motor 4 while the form-fitting coupling 60 is engaged, since the motor start-up blocking device has not yet issued a release signal and thus has also safely switched off, for example, a frequency converter of the drive motor 4.

[0139] Reference Fig.29 The switch 73 of the motor start blocking device can be constructed as a magnetic proximity switch between the eccentric 40 and the angle plate 75 of the grinding machine housing 16, for example, and detects the position of the mechanical operating device 66. Only when the grinding machine drive locking device 74 is in the unlocked state, the release signal of the starter motor 4 is sent.

[0140] Refer again Figure 5-16 , the operation and function of the grinder drive locking device 74 for locking the grinding machine drive by means of a form-fitting coupling 60 can be summarized as follows. The user inserts the closing element 22 into the closing sleeve 30 and rotates the closing element 22 in the closing direction. Here, the closing element 22 is first locked and the form-fitting coupling 60 is only separated when it is further rotated. This makes it possible to reliably prevent the following state from occurring, in which the closing element 22 is not locked, but the form-fitting coupling 60 is separated. When opening the closing element 22, it is ensured in the opposite way that the form-fitting coupling 60 is first engaged in order to lock the grinding machine drive, while during this time the grinding machine housing door 18, i.e. the transverse bolt 26, is still locked in the closing sleeve 30. Only at the end of the opening rotational movement of the closing element 22, after the form-fitting coupling 60 has been engaged, is the closing element 22 reached. Figure 8 3, in which the closure element 22 can be pulled out of the closure sleeve 30 again in order to swing the grinding machine housing door 18 open. The groove 76 with ends 76a, 76b extending 90° around the closure sleeve 30 forms a guide for the transverse bolt 26 ( Figure 5-6 The groove 76 also has an adjustment feature, by means of which the closing element 22 and thus the grinding machine housing door 18 are adjusted.

[0141] The mechanical actuating device 66 has two-sided stops for the movement into the locked or unlocked state of the grinding machine drive locking device 74 , which are provided in the present example by the linear guide 46 .

[0142] When the grinder housing door 18 is fully swung open, the user can axially access the grinding chamber 82 and the rotor grinder 84 arranged therein, which has a cutting rotor 86 that rotates coaxially with the drive axis X and a plurality of axially extending fixed mating cutting elements 88 that are arranged around the cutting rotor 86. The cutting rotor 86 is preferably placed on the drive shaft and axially tightened and driven by form-fitting elements. When the grinder housing cover 18 is fully opened, the user can axially remove the cutting rotor 86 from the drive shaft and axially withdraw it through the axial user access opening 94. During operation, the cutting rotor 86 rotates and the grinding material is fed to the rotor grinder 84 via the charging funnel 24 through the radial grinding material charging opening 25 and is comminuted by the cutting action between the rotor cutting elements 90 of the cutting rotor 86 and the fixed mating cutting elements 88. The comminuted grinding material then drips downwards, for example, through a screen 98 into a collecting container 99.

[0143] Reference Figure 18-22 The laboratory grinder 1 in the form of a knife grinder has a grinding container 17, the interior of which defines a grinding chamber 82 and which is placed vertically on the lower part 12a of the device housing 12. A drive motor (not shown here) is arranged in the device housing 12 and drives a grinding rotor 86 in the form of a rotor knife (not shown) arranged in the grinding chamber 82 of the grinding container 17 via a vertical drive shaft. Such knife grinders are known in principle to those skilled in the art (see 11, www.fritsch.de).

[0144] The space around the grinding container 17 can be closed by a safety cover 19 (in this example in the form of a swingable safety cover), so that the grinding container 17 is reliably enclosed by the device housing 12. The grinding container 17 can also have an inner cover 104, but this inner cover does not have to fulfill the safety function. When the safety cover 19 is closed, as in a cutting grinder, the closure element 22 engages in the closure sleeve 30, is coupled to the mechanical operating device 66, and thus closes the mechanical operating chain 65 and locks on the housing and operates the grinding machine drive locking device 74 via the mechanical operating chain 65. In addition, the mechanical operating chain 65 and the grinding machine drive locking device 74 are as in Figure 1-17 In order to avoid repetition, reference is made to the description therein and it is introduced here.

[0145] Reference Figure 23-28The knife grinder can also work with a safety cover 19, which reliably closes the upper opening of the grinding container 17, but leaves the periphery of the grinding container 17 free. The operating device 66 can be arranged laterally in the tower-shaped housing part 106, for example. Safety is ensured by the safety cover 19, which is as shown in Figure 1-22 In the cutting or knife grinder shown in FIG, the grinding machine drive locking device 74 cooperates with the grinding machine drive locking device 74. In addition, the mechanical operating chain 65 and the grinding machine drive locking device 74 are as shown in FIG. Figure 1-22 In order to avoid repetition, reference is made to the description therein and it is introduced here.

[0146] It is obvious to a person skilled in the art that the embodiments described above are to be understood as exemplary and that the invention is not limited to these embodiments but can be varied in many ways without exceeding the scope of protection of the claims. The corresponding components of the exemplary cutting grinder and knife grinder can be interchanged with each other, wherein the safety cover 19 of the knife grinder or the punch grinder is functionally equivalent to the grinding machine housing door 18 of the cutting grinder, the impact cross grinder or the disc grinder. It can also be seen that the features, whether they are disclosed in the description, the claims, the drawings or in other ways, define important components of the invention individually, even if they are described together with other features.

Claims

1. A laboratory grinder (1) for comminuting grinding materials, in particular configured as a cutting grinder, an impact cross grinder, a disc grinder, a knife grinder or a punch grinder, the laboratory grinder comprising a device housing (12), a grinding machine housing (16) and / or a grinding container (17), A grinding chamber (82) is located in the grinding machine housing (16) or the grinding container (17), wherein: A grinder (84) can be arranged in the grinding chamber (82), with which the grinding material is comminuted, and wherein the grinder housing (16) or the grinding container (17) has a user access opening (94), A grinding machine housing door (18) or a safety cover (19) for closing a user access opening (94), wherein the grinding machine housing door (18) or the safety cover (19) has an open state and a closed state, wherein a user can access the grinding machine (84) through the user access opening (94) when the grinding machine housing door (18) or the safety cover (19) is in the open state, a grinding machine drive device (2, 4) for driving a grinding machine (84), The grinding machine housing door (18) or the safety cover (19) has a closing element (22), by which the grinding machine housing door (18) or the safety cover (19) can be locked in a closed state, and The laboratory grinding machine (1) has a mechanical grinding machine drive locking device (74).

2. The laboratory grinder (1) according to claim 1, wherein: The grinding machine drive locking device (74) is operated by the closing element (22), and the closing element (22) locks the mechanical grinding machine drive locking device (74) when the closing element (22) is opened, wherein the grinding machine drive device (2, 4) is locked, and / or the closing element (22) unlocks the mechanical grinding machine drive locking device (74) when the closing element (22) is closed, wherein the grinding machine drive device (2, 4) is released.

3. The laboratory grinder (1) according to any one of the preceding claims, wherein The invention comprises a mechanical operating device (66), and when the grinding machine housing door (18) or the safety cover (19) is closed, the closing element (22), the mechanical operating device (66) and the grinding machine drive locking device (74) form a mechanical operating chain (65), and wherein the movement of the closing element (22) is mechanically transmitted to the grinding machine drive locking device (74) through the mechanical operating chain (65) so as to lock and / or unlock the grinding machine drive locking device (74).

4. The laboratory grinder (1) according to any one of the preceding claims, wherein When the closure element (22) is opened, the mechanical grinding machine drive locking device (74) is first locked and the grinding machine drive (2, 4) is locked, and as long as the mechanical grinding machine drive locking device (74) is not locked, the unlocking of the grinding machine housing door (18) or the safety cover (19) is mechanically locked by the closure element (22), and / or wherein When the closure element (22) is closed, the grinding machine housing door (18) or the safety cover (19) is first locked, and only after the grinding machine housing door (18) or the safety cover (19) has been locked, the mechanical grinding machine drive locking device (74) is unlocked and the grinding machine drive device (2, 4) is released.

5. The laboratory grinder (1) according to any one of the preceding claims, wherein The grinding machine drive device comprises a drive motor (4) and a drive shaft (2), wherein the drive shaft is connected to the grinding machine (84) so ​​as to drive the grinding machine (84), and wherein, when the grinding machine housing door (18) or the safety cover (19) is not locked, the mechanical grinding machine drive locking device (74) acts on the drive shaft (2) and mechanically locks the rotation of the drive shaft (2).

6. The laboratory grinder (1) according to any one of the preceding claims, wherein The mechanical grinding machine drive locking device (74) has a form-fitting coupling part (60), which releases the grinding machine drive device (2, 4) in a disengaged state and locks the grinding machine drive device (2, 4) in a form-fitting manner in an engaged state, wherein the form-fitting coupling part (60) in particular includes a stator coupling part (56) connected to the device housing (12) and a rotor coupling part (58) connected to the grinding machine drive device and / or a rotating part of the grinding machine (84), and wherein the stator coupling part (56) and the rotor coupling part (58) in a form-fitting manner lock the rotation of the grinding machine (84) in a form-fitting manner in the form-fitting engaged state.

7. The laboratory grinder (1) according to claim 6, wherein: The form-fitting coupling (60) is engaged and disengaged by axial movement of the stator coupling part (56) and / or the rotor coupling part (58) in order to lock and unlock the grinding machine drive locking device (74).

8. The laboratory grinder (1) according to claim 6 or 7, wherein: The form-fitting coupling (60) comprises a stator coupling ring (57) and a rotor coupling ring (59) arranged around the drive shaft (2), wherein the stator coupling ring (57) is fixed to the device housing (12) and the drive shaft (2) rotates in the stator coupling ring (57) in the disconnected state of the coupling (60), and wherein the rotor coupling ring (59) is fixed to the drive shaft (2).

9. The laboratory grinder (1) according to any one of the preceding claims, wherein: The invention comprises a mechanical operating device (66), to which the closing element (22) is coupled when the grinding machine housing door (18) or the safety cover (19) is closed, and the mechanical operating device mechanically transmits the movement of the closing element (22) to the grinding machine drive locking device (74) when the grinding machine housing door (18) or the safety cover (19) is locked and unlocked.

10. The laboratory grinder (1) according to claim 9, wherein: The closing element (22) and the mechanical operating device (66) have complementary coupling elements (34, 36), which are coupled to each other when the grinding machine housing door (18) or the safety cover (19) is closed and / or are decoupled from each other when the grinding machine housing door (18) or the safety cover (19) is opened, wherein in the coupled state, the movement of the closing element (22) is mechanically transmitted to the grinding machine drive locking device (74) via the coupled coupling elements (34, 36) and the mechanical operating device (66), so as to unlock the grinding machine drive locking device (74) and release the grinding machine drive device (2, 4) when the closing element (22) is closed, and / or to lock the grinding machine drive locking device (74) and lock the grinding machine drive device (2, 4) when the closing element (22) is opened.

11. The laboratory grinder (1) according to any one of the preceding claims, wherein The closure element (22) comprises a key (28) which engages in a closure sleeve (30) and by turning the key (28) in the closure sleeve (30) locks and unlocks the grinding machine housing door (18) or the safety cover (19) and operates the unlocking and locking of the grinding machine drive locking device (74).

12. The laboratory grinder (1) according to any one of the preceding claims, wherein A transverse slide (44) is included, and manipulation of the closure element (22) causes transverse movement of the transverse slide (44).

13. The laboratory grinder (1) according to claim 12, wherein: The mechanical operating device (66) comprises an operating shaft (38) and an eccentric disk (40) connected to the operating shaft (38), wherein the operating shaft (38) is rotated by the closing element (22) and the eccentric disk (40) converts the rotational movement into a transverse displacement of the transverse slide (40).

14. The laboratory grinder (1) according to any one of the preceding claims, wherein It comprises a control device and an electrically activatable holding device (72), wherein the control device activates the holding device (72) when the laboratory grinder (1) is in operation, wherein the activated holding device (72) holds the mechanical operating device (66) and prevents the closing element (22) from moving by the holding, and / or wherein the control device deactivates the holding device (72) when the grinding machine drive (2, 4) is stopped.

15. The laboratory grinder (1) according to any one of the preceding claims, wherein When the closure element (22) is opened, the movement of the closure element (22) is transmitted to the grinding machine drive locking device (74) by a rigid mechanical coupling via the mechanical operating device (66) in order to engage the form-fitting coupling part (60) and lock the grinding machine drive locking device (74), and / or wherein, When the closure element (22) is closed, the movement of the closure element (22) is transmitted to the grinding machine drive locking device (74) via the mechanical operating device (66) in order to unlock the mechanical grinding machine drive locking device (74), and the separation of the form-fitting coupling (60) is achieved by a spring force (70).

16. A laboratory mill (1) for comminuting grinding material, in particular a laboratory mill according to any of the preceding claims and in particular in the form of a cutting mill, an impact cross mill or a disc mill, comprising A device housing (12) having a grinding machine housing (16), A grinding chamber (82) is located in the grinding machine housing (16), wherein: A grinder (84) can be arranged in the grinding chamber (82), with which grinding material is comminuted, and wherein the grinder housing (16) has a user access opening (94), A grinding machine housing door (18) for closing the user access opening (94), wherein the grinding machine housing door (18) has an open state and a closed state, wherein a user can access the grinding machine (84) through the user access opening (94) in the open state of the grinding machine housing door (18), a grinding machine drive device (2, 4) for driving the grinding machine (84), The grinding machine housing door (18) has a door lock (22'), by which the grinding machine housing door (18) can be locked in a closed state, and The laboratory grinding machine (1) has a mechanical grinding machine drive locking device (74).

17. A laboratory grinder (1) for comminuting grinding material, in particular a laboratory grinder according to any one of the preceding claims and in particular in the form of a knife grinder or a punch grinder, comprising The device housing (12) and the grinding container (17), A grinding chamber (82) in a grinding container (17), wherein: A grinder (84) having a grinder rotor can be arranged in the grinding chamber (82), by means of which the grinding material is comminuted, and wherein the grinding container (17) has a user access opening (94). A safety cover (19), wherein the safety cover (19) has an open state and a closed state, wherein the safety cover (19) in the open state enables a user to access the grinding machine rotor through a user access opening (94), A grinding machine drive device (2, 4) for driving a grinding machine rotor, The safety cover (19) has a closure element (22), by means of which the safety cover (19) can be locked in a closed state, and The laboratory grinding machine (1) has a mechanical grinding machine drive locking device (74).

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