Laboratory mill

Abstract

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

Description

[0001] Laboratory mill

[0002] Area of

[0003] The invention relates to a laboratory mill, in particular a cutting mill, a cross beater mill, a disc mill, a knife mill or an impact mill on a laboratory scale, which have a grinding mechanism in which the material to be ground is comminuted, for example, in a gap between a grinding mechanism rotor and one or more stationary counter-elements, between two discs or by a rotor knife or impact rotor.

[0004] Background and general description of the invention

[0005] Cutting mills comminute material to be ground between a rotating cutting rotor with one or more essentially axially extending rotor cutting edges and one or more likewise essentially axially extending stationary counter cutting edges, based on the scissor principle. Such laboratory cutting mills are particularly suitable for comminuting tough or fibrous samples, e.g., biological samples such as straw, but also plastic films, to name just a few examples. Examples of current laboratory cutting mills include the PULVERISETTE® 19 and the PULVERISETTE® 15 from the applicant, to whose basic design reference is hereby made. Corresponding product descriptions of the PULVERISETTE® 19 and the PULVERISETTE® 15 can be found, for example, at www.fritsch.de.

[0006] In these laboratory-scale cutting mills, more or less free-flowing bulk material is typically fed into the grinding chamber, e.g., via a hopper, where the cutting rotor rotates around a horizontal axis. The cutting rotor can have different geometries, e.g., with straight cutting edges or so-called V-cutting edges. The latter feature a twist and thus achieve a good cutting effect, especially when comminuting tough, elastic materials and films.

[0007] Below the cutting rotor is typically a sieve, e.g., a sieve cassette, through which the sample material that has already been sufficiently comminuted can trickle to be collected in a collecting vessel below. For further design details of a cutting mill, which are generally known to those skilled in the art, reference is made to the product descriptions for the applicant's PULVERISETTE® 19 and PULVERISETTE® 15 cutting mills, which were available for download at www.fritsch.de at the time of application and its disclosure, and which are hereby incorporated by reference with regard to the basic design of such a cutting mill. Furthermore, the applications DE 196 01 594, DE 10 2018 113 751 A1, WO 2020 / 200759 A1 and DE 10 2019 133 437 A1 describe such cutting mills and are hereby also incorporated by reference.

[0008] Potential injury hazards for the user of a cutting mill can occur in the grinding chamber between the rotating cutting rotor and the stationary counter-blades or counter-knives. Similar hazards can also arise with cross beater mills (see PULVERISETTE® 16, www.fritsch.de) or disc mills (see PULVERISETTE® 13, www.fritsch.de), whose product descriptions are hereby incorporated by reference. These laboratory mills also feature a rotor grinder in which the material to be ground is comminuted between a grinder rotor and stationary counter-elements of the rotor grinder. Similar hazards can also arise with knife mills, in which a rotor knife rotates around a vertical axis in a grinding vessel (see

[0009] PULVERISETTE® 11, www.fritsch.de) or impact mills, sometimes also referred to as rotor high-speed mills, in which an impact rotor rotates in a ring sieve around a vertical axis in a grinding vessel designed as a collecting vessel (cf. PULVERISETTE® 14, www.fritsch.de), the product descriptions of which are hereby also incorporated by reference.

[0010] With such grinders, it must be safely prevented that the user can reach the grinder, especially in the area of ​​the grinder rotor or between the grinder rotor and the stationary counter elements, with a finger during the grinding process and it must be safely prevented that the grinder rotor starts up in the event of a fault, e.g. in the event of a software error, when the grinder is open.

[0011] Referring again to the example of a cutting mill, the grinding chamber is typically closed with a front door. The door can be electronically monitored and locked to protect the user. Such mills can, for example, be equipped with an electric locking device to prevent the door from being opened while the mill is in operation. Blade mills typically have a suitably secured lid, e.g., in the form of a device hood, which, when closed, prevents access to the interior of the grinding vessel with the rotor blades located therein.

[0012] For such electrical or electronic safety systems, dual-channel or redundant circuits are required due to safety requirements, as well as diversely redundant standstill monitoring to avoid residual hazards in the event of electrical malfunctions.

[0013] Mills can also have a motor brake, which is flanged to the rear of the motor shaft, for example, to enable faster deceleration of the motor shaft. For safety reasons, the motor brake brakes when de-energized, and to operate the mill, the brake shoes are actively released from the motor shaft by applying current. However, motor brakes are subject to high wear and typically do not offer any monitoring to ensure they are functioning properly. Furthermore, such motor brakes require a constant supply of electrical energy during operation to remain released. Furthermore, a brake is typically not a safety-related component as defined by DIN EN ISO 12100, so additional electrical safety measures are required.

[0014] DIN EN ISO 12100 - "Safety of machinery" contains general design principles for machines as well as for risk assessment and risk reduction and is relevant, among other things, for CE approval of laboratory equipment. According to DIN EN ISO 12100, the term "safety of machinery" describes the ability of a machine to fulfil its intended functions throughout its entire service life without giving rise to unacceptably high risks.

[0015] In order to meet the safety requirements of DIN EN ISO 12100, cutting mills, for example, typically have a number of electrical safety-related components as follows:

[0016] 1 . A secure door contact,

[0017] 2. A secure door locking device, 3. A secure feedback of the door locking device to the control unit of the cutting mill,

[0018] 4. A diverse redundant safe standstill detection for the drive,

[0019] 5. A safe momentary shutdown of the drive,

[0020] 6. A safe status feedback from each safe circuit and signaling device to the control device of the cutting mill, where “safe” is to be understood in the sense of DIN EN ISO 12100

[0021] Although laboratory mills with electrical or electronic safety devices or motor brakes have generally proven to be effective, they can be cost-intensive and could be further improved with regard to potential susceptibility to errors.

[0022] The object of the invention is to provide a laboratory mill which meets high safety standards, in particular with regard to user access to the grinding mechanism.

[0023] Another aspect of the task is to provide a laboratory mill that is simple, cost-effective and less prone to errors.

[0024] A further aspect of the task is to provide a laboratory mill that has a cost-effective, low-error-prone safety device against unwanted user access to a grinding mechanism, that is compact in design and that can also be integrated into simple and small laboratory mills.

[0025] A further aspect of the task is to provide a safe laboratory mill - particularly in accordance with DIN EN ISO 12100 - that avoids or at least mitigates the disadvantages described above.

[0026] The object of the invention is achieved by the subject matter of the independent claims. Advantageous developments of the invention are defined in the subclaims.

[0027] A laboratory mill for comminuting material to be ground is provided, comprising a device housing with a grinder housing and / or a grinding vessel. The grinder housing or the grinding vessel defines a grinding chamber in the grinder housing or in the grinding vessel, in which a particularly rotating grinder is arranged or inserted, with which the material to be ground is comminuted when the grinder is operating. The grinder housing or the grinding vessel has a particularly axial user access opening, through which the user gains access to the grinder when opened.

[0028] The user access opening can be closed with a grinder housing door or a safety lid, so that the grinder housing door or the safety lid defines an open and a closed state and the user has access to the grinder through the user access opening when the grinder housing door or the safety lid is open, and the grinder is securely enclosed in the closed state in order to operate the laboratory mill, so that the user certainly has no access to the grinder during operation.

[0029] The grinder is designed, in particular, as a rotor grinder. The laboratory mill also features a motorized grinder drive for rotating the grinder, e.g., with an electric motor and a drive shaft.

[0030] The grinder housing door or the safety lid has a locking element with which the grinder housing door or the safety lid is mechanically locked in the closed state in order to operate the laboratory mill safely.

[0031] Advantageously, the laboratory mill has a mechanical grinder drive lock, with which the grinder drive can be mechanically blocked. The grinder drive lock is mechanically actuated, in particular directly or indirectly, by the closure element.

[0032] The laboratory mill can be designed in particular as a cutting mill, cross beater mill, disc mill, knife mill or impact mill. In a cutting mill, cross beater mill or disc mill, an optionally solid grinder housing is preferably present around the rotor grinder and the grinder housing is closed with a grinder housing door. In this case, the closure element for the grinder housing door can also be referred to as a door closure. A knife mill or an impact mill can have a grinding vessel, for example made of (transparent) plastic or stainless steel, in which the grinder rotor, e.g. a rotor knife or an impact rotor, is arranged, which rotates around a vertical axis. The knife mill and the impact mill can (but do not have to) additionally have an outer housing around the grinding vessel with a closure hood.In a knife mill or impact mill with an additional housing, the safety lid can be designed as the closure hood, and the locking element can be attached to the safety lid designed as a closure hood and lock it when closed. In a knife mill or impact mill that does not have an additional closed housing, at least the safety lid is still present, securely closing the grinding vessel at the top. In this case, too, the locking element can be attached to the safety lid and lock it when closed, thus preventing tampering with the grinding vessel.

[0033] The grinder drive lock mechanically blocks the grinder drive when the grinder housing door or safety lid is unlocked and releases the grinder drive when the grinder housing door or safety lid is locked. For this purpose, the locking element and the grinder drive lock can be connected to each other via a mechanical manipulation chain when the grinder housing door or safety lid is closed. On the other hand, the mechanical manipulation chain can be interrupted when the grinder housing door or safety lid is opened. In other words, the movement of the locking element when unlocking and locking the grinder housing door or safety lid can be mechanically transmitted to the grinder drive lock via the closed mechanical manipulation chain in order to lock and unlock the grinder drive lock.

[0034] The laboratory mill can be designed, for example, as a cutting mill, cross beater mill, disc mill, knife mill or impact mill on a laboratory scale. In a cutting mill or cross beater mill, the grinding mechanism has one or more stationary cutting edges and a coaxial cutting rotor rotating within the stationary cutting edges, preferably about a horizontal axis. A cutting mill works according to the scissors principle, whereby the material to be ground is cut between the cutting edges of the cutting rotor and the counter-cutting edges. A cross beater mill is similarly constructed but has a larger gap between the cutting edges and counter-cutting edges. In a disc mill, the rotor grinding mechanism has a rotating disc and a stationary disc which are axially opposite one another, and whereby the material to be ground is comminuted in the gap extending transversely between the two discs.In an impact mill, a rotor rotates around a preferably vertical axis, e.g., within a ring screen, and grinds the material to be ground through the impact of the rotor teeth. The rotor grinding mechanism and the ring screen can be arranged in a grinding vessel, which in turn is inserted into an outer casing. In a knife mill, a rotor blade rotates around a vertical axis in the grinding vessel without counter-blades. An additional outer casing around the grinding vessel is possible but not mandatory.

[0035] A laboratory mill is particularly large enough to be placed in a standard laboratory space, e.g. on a laboratory table, or to stand on feet on the laboratory floor.

[0036] The axial user access opening preferably serves to provide the user with axial access to the grinding chamber, e.g., to remove grinding material or the grinding rotor from the grinding chamber, to clean the grinding chamber, or to replace or clean the sieve when the grinder housing door or the cover is open. For this purpose, the grinding rotor can preferably be attached to a drive shaft with a form-locking element and, if necessary, axially screwed or locked. If necessary, it can be removed manually after loosening the screw or lock.

[0037] In a cutting mill, the diameter and / or length of the laboratory mill (cutting) rotor can range from a few millimeters, e.g., 20 mm, up to approximately 15 cm, or a maximum of approximately 20 cm. In a disc mill, the diameter may be larger, e.g., 15 cm to 30 cm.

[0038] In order to be able to feed the ground material into the grinder during operation of the laboratory mill with the grinder housing door or safety cover closed, the grinder housing or safety cover can also have an axial or radial ground material filling opening, e.g. with a filling funnel, through which the ground material can be filled axially or radially into the grinding chamber in order to continuously comminute the ground material with the grinder, e.g. between the grinder rotor and the stationary counter-element(s) or with the rotor blade or impact rotor. In a cutting mill, the ground material filling opening is in particular radial, and in a cross beater mill, disc mill, knife mill, or impact mill it is in particular axial.

[0039] Advantageously, a mechanical grinder drive lock, which mechanically blocks the grinder drive with a positive fit, can ensure a high level of user safety. For example, the grinder rotor, e.g. the cutting rotor, the rotating disc, the rotor blade or the impact rotor, is reliably prevented from rotating when the grinder housing door or the safety cover is opened. Furthermore, possible defects in electronic safety devices do not compromise the safety of the laboratory mill against unintentional opening of the grinding chamber. Furthermore, unintentional and even intentional incorrect operation can be effectively prevented. The mechanically actuated positive locking of the grinder drive is also above average secure against unauthorized manipulation and generally offers a high level of security against potentially injured incorrect operation or unforeseen events. In particular,This means that redundant electronic safety devices, safe contacts, safe locking devices, or electrical status feedback to the control device are not required. Nevertheless, the safety requirements for laboratory equipment as defined by DIN EN ISO 12100 or to obtain a CE mark can be met.

[0040] The grinder drive can comprise a drive motor, in particular an electric motor, and a drive shaft connected to the grinder to drive the grinder in rotation. The mechanical grinder drive lock can engage the drive shaft and mechanically block the rotation of the drive shaft if the grinder housing door or the safety cover is not locked. The grinder drive lock can preferably be arranged between the drive motor and the grinder rotor. A direct, positive locking of the drive shaft ensures a high level of safety, e.g., against electrical malfunctions of the grinder drive.

[0041] According to one embodiment, the mechanical grinder drive lock has a positive-locking, in particular axially positive-locking coupling, which, in the disengaged state, releases the grinder drive for rotation and, in the engaged state, positively blocks the grinder drive.

[0042] The axially positive coupling can comprise a stator coupling part connected to the device housing and a rotor coupling part connected to the rotating parts of the grinder drive and / or the grinder. When the stator coupling part and the rotor coupling part are positively engaged, the coupling positively blocks the rotation of the grinder drive and / or the grinder.

[0043] Preferably, the positive-locking coupling is mechanically actuated directly or indirectly by the locking element, e.g., via the mechanical manipulation chain. In the case of a rotatable locking element, for example, the rotational movement of the locking element can be converted into a movement that mechanically engages and disengages the positive-locking coupling.

[0044] The engagement and disengagement of the positive clutch can be achieved, for example, by axial displacement of the stator clutch part and / or the rotor clutch part. The stator clutch part and the rotor clutch part can have complementary teeth that mesh positively, particularly axially, when the positive clutch is engaged, in order to positively block the rotation of the grinding mechanism. The teeth can preferably taper toward the other complementary clutch part to facilitate engagement. This can largely prevent engagement from being impossible when the teeth are positioned tooth-to-tooth.

[0045] When the locking element is moved to open it, the mechanical grinder drive lock or the positive-locking clutch is engaged first. Only after the mechanical grinder drive lock or the positive-locking clutch has been engaged and the grinder drive has been positively blocked is further opening of the locking element mechanically possible, up to and including the unlocking of the grinder housing door or the safety cover. In other words, the unlocking of the grinder housing door or the safety cover is mechanically blocked, and the grinder housing door or the safety cover cannot be unlocked as long as the mechanical grinder drive lock is not locked or the positive-locking clutch is not engaged. When the locking element is moved to close it, the grinder housing door or the safety cover is locked first.the safety lid is locked, and only after the grinder housing door or the safety lid has been locked, the mechanical grinder drive lock is unlocked or the positive coupling is disengaged upon further closing of the locking element, allowing the grinder drive to rotate. Unlocking the grinder drive lock or disengaging the positive coupling is therefore not mechanically possible, at least not until the locking element has been locked. The opening of the locking element therefore takes place in two phases of the locking element's movement. In a first phase, the locking element first actuates the locking of the grinder drive lock via the mechanical manipulation chain, and only then, in a second phase, does the locking element unlock the grinder housing door or the safety lid.Closing the locking element also involves two phases of movement. In a first phase, the locking element first locks the grinder housing door or safety cover. Only then, in a second phase, does the locking element unlock the grinder drive lock via the mechanical manipulation chain.

[0046] The movement of the locking element when closing occurs in particular in chronologically successive movement phases:

[0047] 1. Lock the grinder housing door or the safety cover by closing the door, e.g. turning the locking element in the closing direction, while the grinder drive lock remains locked,

[0048] 2. Unlocking the grinder drive lock during a continuous closing movement, e.g., rotating the locking element in the closing direction, whereby the locking element keeps the grinder housing door or the safety cover locked. The movement of the locking element during opening occurs primarily in sequential movement phases:

[0049] 1. Locking the grinder drive lock by opening movement, e.g. rotation of the locking element, whereby the locking element keeps the grinder housing door or the safety cover locked,

[0050] 2. Unlock the grinder housing door or the safety cover with a continuous opening movement, e.g. turning the locking element, whereby the

[0051] Grinder drive lock remains locked.

[0052] In other words, the laboratory mill has four states as follows:

[0053] 1. The grinder housing door or safety cover is open and the grinder drive lock is engaged, allowing the user safe access to the grinder.

[0054] 2. The grinder housing door or safety cover is closed but not locked, and the grinder drive lock is locked.

[0055] 3. The grinder housing door or safety cover is closed and locked, but the locking element has not yet been moved to the stop, whereby the grinder drive lock is locked.

[0056] 4. The grinder housing door or safety cover is closed, locked and the locking element is moved to the stop, whereby the grinder drive lock is unlocked.

[0057] To start up the laboratory mill, the user operates the following steps, starting with the grinder housing or safety cover open and the grinder drive lock locked:

[0058] 1 . The user closes the grinder housing door or safety cover, whereby the grinder drive lock is locked.

[0059] 2. The user moves the locking element in the closing direction, initially locking the grinder housing door or the safety lid, while the grinder drive lock remains locked. 3. The user moves the locking element further in the closing direction until it stops, which unlocks the grinder drive lock.

[0060] To open the laboratory mill, the user operates the following steps, starting from the closed state of the grinder housing or safety cover and the unlocked state of the grinder drive lock:

[0061] 1 . The user moves the locking element from the stop in the opening direction, which initially activates the locking of the grinder drive lock.

[0062] 2. The user moves the locking element further in the opening direction and thus unlocks the grinder housing door or the safety cover, whereby the previously locked grinder drive lock remains locked.

[0063] 3. The user opens the grinder housing door or safety cover to gain access to the grinder, while the grinder drive lock remains locked.

[0064] This ensures that the grinder drive is securely mechanically blocked and cannot continue any residual rotation the moment the grinder housing door or safety cover is unlocked, and thus safely before the grinder housing door or safety cover can be opened. Furthermore, starting with the grinder housing door or safety cover open, for example, in the event of an electronic malfunction, is reliably prevented, thus ensuring a high level of safety.

[0065] Preferably, the positive coupling comprises a stator coupling ring and a rotor coupling ring arranged around the drive shaft. The stator coupling ring can be secured to the device housing in a substantially rotationally fixed manner, except for a certain angular play, and the drive shaft can rotate within the stator coupling ring. The rotor coupling ring can be secured to the drive shaft in a substantially rotationally fixed manner.

[0066] The positive-locking clutch can preferably be engaged in any desired rotational position of the grinder rotor, in particular without starting up the drive motor. This can be achieved, for example, in that at least one of the positively engaging clutch parts has at least enough play relative to the other clutch part to allow the clutch to engage in a positive fit, e.g. the teeth of the clutch can engage in a positive fit, even if the grinder rotor is wedged, e.g. by material to be ground. The play is preferably present on both sides so that the clutch can fully engage in any desired rotational position of the grinder rotor and the grinder housing door can be opened. For this purpose, it is advantageous, for example in the case of an axially positive-locking clutch, for the clutch to have a large number of teeth and / or the axially positive-locking clutch orAt least one of the two clutch rings has some angular play in both directions of rotation, at least enough so that even with a completely jammed grinder rotor, the clutch teeth can still fully engage in any rotational position of the grinder rotor. The play on both sides or angular play is preferably balanced centrally when the clutch is disengaged.

[0067] The positive clutch can engage and disengage by axial displacement of the stator clutch ring and / or the rotor clutch ring to lock and release the grinder drive lock.

[0068] According to an exemplary embodiment, the positive coupling may comprise an axial pressure plate which is actuated by the movement of the closure element when the closure element is moved in the opening direction in order to positively couple the stator coupling ring and the rotor coupling ring to one another.

[0069] As part of the mechanical manipulation chain, a mechanical manipulation device can be included, to which the closure element couples when the grinder housing door or the safety lid is closed, and which mechanically transmits the movement of the closure element when locking and unlocking the grinder housing door or the safety lid to the grinder drive lock in order to unlock or lock it. The mechanical manipulation device can therefore form the mechanical link between the closure element and the grinder drive lock in the mechanical manipulation chain, so that the mechanical actuation of the grinder drive lock by the closure element takes place indirectly via the mechanical manipulation device.According to one embodiment, the mechanical manipulation device allows the stator coupling part a sufficient degree of rotational play that the teeth of the stator coupling part and the rotor coupling part can still engage due to the rotational play, for example if the grinder were jammed by ground material within the grinder housing. Alternatively or additionally, the rotor coupling part could also have this slight degree of rotational play with respect to the drive shaft. This can facilitate the engagement of the positive coupling while maintaining the safety features. Furthermore, as already explained above, engagement can be facilitated by tapered teeth, e.g., with a triangular cross-section.

[0070] For coupling when closing the grinder housing door or the safety lid, the closure element and the mechanical manipulation device can have mutually complementary coupling elements which couple to each other when closing the grinder housing door or the safety lid and decouple from each other when opening the grinder housing door or the safety lid, so that in the coupled state with the grinder housing door closed or with the safety lid closed, the movement of the closure element is mechanically transmitted via the coupled coupling elements and the mechanical manipulation device to the grinder drive lock in order to release the grinder drive lock when closing the closure element and to lock the grinder drive lock when opening the closure element and to block the grinder drive. Complementary coupling elements have proven to be suitable, for example:Complementary dihedrals or multi-edges that engage axially when the grinder housing door or safety cover is closed have proven advantageous. Dihedrals also have the advantage that they can only be coupled in two orientations rotated by 180°.

[0071] The locking element can, for example, be designed as a key with a rotary handle that engages a locking sleeve on the grinder housing, whereby the grinder housing door or the safety cover is locked by turning the key in the locking sleeve. For example, the key can have two transverse locking bolts that engage in the complementary locking sleeve and lock in the locking sleeve when turned (key-lock principle). In this case, it is advantageous if the locking already begins with a small angle of rotation of the key, and the disengagement of the positive coupling only begins with further rotation of the key when closing the grinder housing door or the safety cover, i.e. with continuous key rotation only after the key has already locked.

[0072] Accordingly, when the grinder housing door or the safety cover is closed, the key can form the mechanical manipulation chain with the grinder drive lock via the coupled coupling elements and the mechanical manipulation device, such that a rotation of the key via the coupled coupling elements, e.g. the two-flat, and the mechanical manipulation device causes the locking and unlocking of the grinder drive lock.

[0073] This allows a simple and cost-effective, yet secure locking of the grinder housing door or the safety cover in conjunction with the drive lock.

[0074] According to one embodiment, the mechanical manipulation device can comprise a transverse slide, e.g., a transverse sliding plate, wherein actuation, e.g., rotation of the closure element, causes a transverse displacement of the sliding plate relative to the drive shaft. This allows the mechanical manipulation device to be compactly integrated into the drive concept of a laboratory mill, while the mechanism for effecting the drive blocking can still be designed to be stable and thus safe.

[0075] According to one embodiment, the mechanical manipulation device can comprise a manipulator shaft and an eccentric. The manipulator shaft can have one of the two complementary coupling elements, so that the locking element or the key, comprising the other of the two complementary coupling elements, releasably couples to the manipulator shaft when the grinder housing door or the safety cover is closed and / or the locking element or the key is inserted into the locking sleeve. In the coupled state of the complementary coupling elements, the manipulator shaft can be rotated by rotating the locking element or key, and the eccentric converts the rotational movement into a transverse displacement of the sliding plate.

[0076] Furthermore, the mechanical manipulation device can have at least one wedge element which converts the transverse displacement of the sliding plate into an axial displacement of the positive coupling, ie of the stator coupling part or ring and / or the rotor coupling part or ring, e.g. via an axially movable pressure plate which engages the positive coupling.

[0077] The essential safety of the laboratory mill can be achieved by the positive mechanical locking of the grinder drive. However, additional electrical or electronic protective measures can also be provided. For example, a control device and an electrically activated holding device, e.g., in the form of an electromagnet, can be included. The control device activates the holding device when the laboratory mill is in operation, and the activated holding device magnetically holds the manipulation device, e.g., the sliding plate. This magnetic locking prevents the locking element from being moved as long as the grinder drive is still rotating.The control device can monitor the rotation of the grinder drive or wait for a predetermined idle run-on time. Only when the control device detects that the grinder drive is no longer rotating or the idle run-on time has expired does the control device deactivate the holding device. This prevents the user from attempting to unlock the locking element and thus engage the positive coupling while the coupling parts are still rotating against each other. While it is mechanically impossible to completely unlock the locking element using the mechanical manipulation chain as long as the positive coupling is not engaged, the holding device can prevent unwanted wear on the positive coupling due to incorrect operation.For this reason, however, it is not necessary to design this additional electronically controlled protective function with safety redundancy, although this should not be ruled out either.

[0078] When the closure element is opened, the movement of the closure element is transmitted via the mechanical manipulation device to the grinder drive lock, rigidly coupled or positively guided, in order to securely lock the grinder drive lock by engaging the positive coupling. The movement of the closure element when closing the closure element is also transmitted via the mechanical manipulation device to the grinder drive lock, unlocking the grinder drive lock and releasing the positive coupling for disengagement. Disengagement of the positive coupling can be effected by one or more spring elements. In other words, engagement of the positive coupling can occur against spring tension. However, positively guided disengagement should not be excluded.

[0079] According to one aspect of the invention, a laboratory mill in the form of a cutting mill, cross-beater mill, or disc mill for comminuting material to be ground is provided, comprising the following: a device housing with a grinder housing, a grinding chamber in the grinder housing, wherein a grinder is arranged in the grinding chamber, with which the material to be ground is comminuted, and wherein the grinder housing has a user access opening, a grinder housing door for closing the user access opening, wherein the grinder housing door has an open and a closed state, wherein the user has access to the grinder through the user access opening when the grinder housing door is open, a grinder drive for driving the grinder, wherein the grinder housing door has a door lock,with which the grinder housing door can be locked in the closed state and wherein the laboratory mill has a mechanical grinder drive lock.,

[0080] According to a further aspect of the invention, a laboratory mill in the form of a knife mill or impact mill for comminuting material to be ground is provided, which comprises the following: a device housing and a grinding vessel, a grinding chamber in the grinding vessel, wherein a rotor grinder with a grinding rotor, in particular rotating about a vertical axis, e.g. a rotor knife or an impact rotor, can be arranged in the grinding chamber, with which the material to be ground is comminuted, and wherein the grinding vessel has a particularly upper user access opening, e.g.of the upwardly open grinding vessel, a safety lid, wherein the safety lid has an open and a closed state, wherein the safety lid in the open state allows the user access to the grinding rotor through the user access opening, in particular from above, a grinding mechanism drive for driving the grinding mechanism rotor, wherein the safety lid has a closure element with which the safety lid can be locked in the closed state and wherein the laboratory mill has a mechanical grinding mechanism drive lock.

[0081] In the following, the invention is explained in more detail using exemplary embodiments and with reference to the figures, wherein identical and similar elements are partly provided with the same reference numerals and the features of the various exemplary embodiments can be combined with one another.

[0082] They show:

[0083] Fig. 1 is a three-dimensional representation of a cutting mill according to an embodiment of the invention,

[0084] Fig. 2 the cutting mill from Fig. 1 with the grinder housing shown transparently,

[0085] Fig. 3 the cutting mill from Fig. 1 with the grinder housing door open,

[0086] Fig. 4 is a partially transparent three-dimensional view of the grinder housing door and the door lock of the cutting mill from Fig. 1 in a slightly opened state,

[0087] Fig. 5 is a partially transparent three-dimensional view of the grinder housing of the cutting mill from Fig. 1 in a slightly opened state seen from the motor side,

[0088] Fig. 6 is a partially transparent three-dimensional representation of the grinding mechanism housing of the cutting mill from Fig. 1 in the closed state, Fig. 7 is a partially transparent three-dimensional representation with the manipulation device in the engaged state of the positive coupling and with the grinding mechanism housing door closed but unlocked,

[0089] Fig. 8 is an enlarged detail of area A in Fig. 7,

[0090] Fig. 9 is an enlarged detail of area B in Fig. 7,

[0091] Fig. 10 a three-dimensional representation of the manipulation device and the positive coupling in the engaged state,

[0092] Fig. 11 is a rear axial view of the manipulation device in the engaged state of the positive coupling,

[0093] Fig. 12 a partially transparent three-dimensional representation of the manipulation device with the grinder housing door closed and locked and with the positive coupling disengaged,

[0094] Fig. 13 is an enlarged detail of area A in Fig. 12,

[0095] Fig. 14 is an enlarged detail of area B in Fig. 12,

[0096] Fig. 15 a three-dimensional representation of the manipulation device and the positive coupling in the disengaged state,

[0097] Fig. 16 a rear axial view of the manipulation device in the disengaged state of the positive coupling,

[0098] Fig. 17 a longitudinal section through the cutting mill from Fig. 1 ,

[0099] Fig. 18 is a three-dimensional representation of a knife mill according to a further embodiment of the invention with the safety cover half-opened,

[0100] Fig. 19 is an enlarged detail of area A in Fig. 18,

[0101] Fig. 20 like Fig. 19, but with almost closed safety cover,

[0102] Fig. 21 a partially cut-away three-dimensional view of the knife mill from Fig. 18 with the safety cover closed,

[0103] Fig. 22 is an enlarged detail of area A in Fig. 21 ,

[0104] Fig. 23 a three-dimensional representation of a knife mill according to another

[0105] Embodiment of the invention with half-open safety lid,

[0106] Fig. 24 is an enlarged detail of area A in Fig. 23,

[0107] Fig. 25 as Fig. 23, but with closed safety cover,

[0108] Fig. 26 an enlarged detail of area A in Fig. 25, Fig. 27 as Fig. 25 with hidden components,

[0109] Fig. 28 is an enlarged detail of area A in Fig. 27,

[0110] Fig. 29 is a partially transparent rear three-dimensional view of the cutting mill from Fig. 1.

[0111] Detailed description of the invention

[0112] 1-17 and 29, a laboratory mill 1 is shown, in the present example in the form of a cutting mill. The laboratory mill 1 has a device housing 12 with a user display 14 for the user to enter grinding parameters into a control device (not shown) of the laboratory mill 1. Arranged on the front 12a of the device housing 12 is a grinder housing 16, which can be closed at the front (axially) with 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 pivoted open and closed about hinges 20. The grinder housing door 18 can be locked with a locking element 22 in the form of a door lock 22' when the grinder housing door 18 is closed, as shown in Fig. 1.Only when the locking element 22 is fully unlocked can the user pivot open the grinder housing door 18 to gain access to the rotor grinder 84, which is located in the interior or grinding chamber 82 of the grinder housing 16. When the grinder housing 16 is closed, the grinding material can be fed in via a filling hopper 24 and, in this example, a radial grinding material filling opening 25, so that grinding material can be continuously fed and comminuted during operation of the cutting mill.

[0113] The locking element 22 comprises, for example, a rotary handle 23 or rotary knob and locking bolts 26, so that a key 28 is formed. The locking element 22 or the key 28 is rotatably arranged in the grinder door 18 and, when rotated in a suitable position, can be inserted into a locking sleeve 30 on the front 16a of the grinder housing 16. Due to the transverse extension of the locking bolts 26, the locking element 22 can only be inserted into the locking sleeve 30 when the locking element 22 is in the unlocking position shown in Fig. 3-4. In the present example, the locking sleeve 30 is designed as a type of keyhole, and when the locking or transverse bolts 26 are vertical, the locking element 22 or the key 28 can engage in the locking sleeve 30.The locking sleeve 30 has transverse recesses 31, similar to a keyhole, into which the locking or cross bolts 26 engage when the key 28 is inserted into the locking sleeve 30 according to the key-keyhole principle. By subsequently rotating the locking element 22 with the cross bolts 26 from the vertical, the cross bolts 26 lock in the locking sleeve 30 and thus lock the grinder housing door 18.

[0114] At one coupling end 32, the closure element 22 has a positive-locking coupling element 34. When the coupling end 32 is inserted into the closure sleeve 30, a positive-locking connection is created between the coupling element 34 and the complementary coupling element 36 of a manipulator shaft 38, in order to establish a positive coupling between the closure element 22 and the manipulator shaft 38. In the present example, the manipulator shaft 38 is rotatably mounted in the closure sleeve 30, and the two complementary positive-locking coupling elements 34, 36 are each designed in the form of complementary dihedrals 35, 37. When the grinder 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-locking manner.If the closure element 22 is then rotated to lock it in the closure sleeve 30 with the grinder housing door 18 closed, the closure element 22 rotates the manipulator shaft 38 via the coupling of the two flats 35, 37. At the end 38b of the manipulator shaft 38 opposite the coupling element 36, an eccentric disc 40 is positively fastened in a defined angular position, e.g. screwed in a defined angular position with mutual positive engagement between the manipulator shaft 38 and the eccentric disc 40.

[0115] The closure element 22, the closure sleeve 30, and the coupling elements 34, 36 are clearly rotationally positioned relative to one another when the manipulation chain 65 is closed by engaging the coupling elements 34, 36, whereby two rotational positions of the closure element 22 are possible in the present example. In other words, the transverse recesses 31 are oriented such that, in the same rotational position of the closure element 22 in which the locking bolts 26 of the closure element 22 engage the transverse recesses 31, the two coupling elements 34, 36 also axially engage with one another. Furthermore, the closure element 22 can only be locked when it has been inserted into the closure sleeve 30 far enough for the two coupling elements 34, 36 to be coupled to one another or the manipulation chain 65 to be closed.

[0116] Referring to Fig. 5-16, the eccentric disc 40 is guided in an opening 42 of a transverse sliding plate 44. When the closure element 22 is manually rotated by the user, the user transmits the rotational movement of the closure element 22 via the coupling elements 34, 36 to the manipulator shaft 38. As a result, the manipulator shaft 38 rotates the eccentric disc 40 in the rectangular opening 42. The sliding plate 44 is guided transversely by a linear guide 46, so that the sliding plate 44, driven by the eccentric disc 40, is displaced, in the present example horizontally, initially driven by the manual actuation, in this example rotation, of the closure element 22. By arranging the eccentric disc 40 in the opening 42, the rotary movement of the closure element 22 or the manipulator shaft 38 is converted into a transverse translational movement of the sliding plate 44. The locking of the locking element 22 orthe grinder housing door 18 simultaneously causes the rotation of the manipulator shaft 38 and the eccentric 40 and thus the transverse displacement of the sliding plate 44.

[0117] A wedge drive 48 with inclined surfaces or lifting wedges 50 is arranged on the sliding plate 44. During the transverse displacement of the sliding plate 44, cylindrical pins 52 of a pressure plate 54 run on the lifting wedges 50, whereby the linear transverse movement of the sliding plate 44 is converted into an axial displacement of the pressure plate 54 with respect to the rotational axis X of the laboratory mill. A stator coupling part 56 in the form of a stator coupling ring 57 is attached to the pressure plate 54 and is moved axially 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 positive engagement elements 62 in the form of complementary teeth 68 and form a positive coupling 60.When the stator coupling part 56 is pushed axially against the rotor coupling part 58 by means of the pressure plate 54 and the complementary teeth 68 of the two coupling parts 56, 58 are brought into axial positive engagement, the coupling 60 engages. The drive shaft 2 of the drive motor 4 (Fig. 17) runs coaxially through the two coupling rings 57, 59 and defines the drive axis X. The rotor coupling ring 59 is fastened to the drive shaft by means of a positive engagement, and thus rotates with the drive shaft. The stator coupling ring 57 is fastened to the device housing 12 by means of the pressure plate 54 in a rotationally fixed manner within a cutout 64 of the sliding plate 44, except for a certain angular play. When the stator coupling ring 57 is axially moved against the rotor coupling ring 59, a positive connection is created which positively locks the drive shaft against rotation.Accordingly, the two clutch parts 56, 58 form clutch halves of a positive-locking clutch 60, which positively locks and blocks the rotation of the drive shaft when the clutch 60 is engaged.

[0118] The mechanical manipulation for engaging the clutch 60 is therefore carried out via a mechanical manipulation chain 65 by rotating the locking element 22, which is connected to the manipulator shaft 38 via the coupling elements 34, 36 when the locking element 22 has been inserted into the locking sleeve 30, further via the eccentric disc 40, which converts the rotational movement into a transverse displacement movement of the sliding plate 44 and the wedge drive 48 with the lifting wedges 50 and the pins 52, which causes the transverse linear displacement of the sliding plate 44 into a linear axial displacement of one of the two coupling halves or coupling parts 56, 58 of the positive coupling 60 in order to engage and disengage the clutch 60.In other words, the manipulator shaft 38, the eccentric disc 40, the sliding plate 44, the wedge drive 48, the lifting wedges 50 and the pressure plate 54 with the pins 52 form an exemplary example of a mechanical manipulation device 66 with which the rotational movement of the closure element 22 is mechanically transmitted to the positive coupling 60 in order to engage and disengage it.

[0119] More generally, the rotation of the locking element 22 during unlocking and locking thereof is converted into an axial displacement by means of which the coupling parts 56, 58 and the coupling 60 are axially engaged and disengaged.

[0120] When the positive clutch 60 is engaged, rotation of the drive shaft is prevented by the pressure plate 54 being located in the rectangular cutout 64 of the sliding plate 44 and being held there in a positive fit. However, the pressure plate 54 has a slight angular play around the drive shaft 2 in the cutout 64, in the present example by bevels 55, when the positive clutch 60 is engaged. This can facilitate the mutual engagement of the complementary teeth 68 when the positive clutch 60 is engaged, since it can be prevented that the teeth 68 are opposite each other in a tooth-to-tooth position and therefore cannot engage. Furthermore, the teeth 68 taper towards the respective opposing clutch ring to further improve engagement. In the present example, the teeth 68 have a triangular cross-section.

[0121] So that when the closure element 22 is locked, i.e. when the sliding plate 44 is retracted, the pressure plate 54 can return to its initial position with the positive-locking clutch 60 disengaged or the drive shaft unlocked, the pressure plate 54 is guided by two spring pressure pieces 70, whose spring-loaded balls engage in conical bores. The pressure pieces 70 cause the pressure plate 54 to resiliently return to the disengaged state of the positive-locking clutch 60. Nevertheless, the pressure pieces 70 allow slight angular rotation about the drive shaft to enable the engagement of the positive-locking clutch 60, even if the grinder rotor 86 is wedged. The spring pressure pieces 70 centrally balance the angular play of the pressure plate 54 in the disengaged state, so that the pressure plate 54 ormore generally, the positive coupling 60 has sufficient angular play in both directions of rotation so that the positive coupling 60 can engage in any rotational position of the drive shaft, even if the grinder rotor 86 is wedged.

[0122] When the laboratory mill 1 is in operation, the closure element 22 is locked, the positive coupling 60 is disengaged, and the sliding plate 44 is in the disengaged position shown in Fig. 12-16. In this state of the locked closure element 22 and the unlocked grinder drive, the sliding plate 44 is magnetically held in place by an electromagnet 72.

[0123] The maximum idle run-on time of the drive is stored in the control device (not shown) of the laboratory mill 1, which is typically housed in the device housing 12, and the control device waits for this maximum idle run-on time before deactivating the holding device, e.g. in the form of the electromagnet 72, whereby the movement of the mechanical manipulation chain 65 is released so that the locking element 22 can be unlocked. By waiting for the maximum idle run-on time, it is ensured that the drive has already come to a standstill when the holding device is deactivated. This eliminates the need for technically complex electrical standstill monitoring of the drive.As long as the drive shaft rotates, the control device keeps the electromagnet 72 activated, so that it holds the sliding plate 44 in place to prevent the user from attempting to open the grinder housing cover 18 while the drive shaft is rotating. Although the unlocking of the locking element 22 from the locking sleeve 30 is mechanically blocked anyway as long as the positive coupling 60 is not engaged, the magnetic retention prevents the user from attempting to engage the positive coupling 60 while rotating. This prevents undesirable wear due to incorrect operation.

[0124] Furthermore, the rotational position of the eccentric 40 and thus the position of the sliding plate 44 or the mechanical manipulation device 66 can be sensed via an electrical motor start prevention device, e.g., a sensor or switch 73. However, this switch need not be a safety switch, since the mechanical locking of the drive means that no injury can occur should the switch fail. Nevertheless, the use of a safety switch should not be ruled out. The same applies to the magnetic holding with the electromagnet 72. The control device of the laboratory mill 1 receives an enable signal from the electrical motor start prevention device, which allows the user to start the drive motor 4.This can prevent the user from attempting to start the drive motor 4 as long as the positive clutch 60 is engaged, since the motor start prevention device has not yet issued an enable signal and thus, for example, the frequency converter of the drive motor 4 is still safely switched off.

[0125] Referring to Fig. 29, the switch 73 of the motor start prevention device can be arranged, for example, as a magnetic proximity switch between the eccentric 40 and, for example, an angle plate 75 of the grinder housing 16 and detect the position of the mechanical manipulation device 66. The enable signal for starting the motor 4 is only issued when the grinder drive lock 74 is in the unlocked state.

[0126] Referring again to Fig. 5-16, the operation and function of the grinder drive lock 74, which blocks the grinder drive by means of the positive coupling 60, can be summarized as follows. The user inserts the locking element 22 into the locking sleeve 30 and turns the locking element 22 in the closing direction. The locking element 22 initially locks, and only upon further rotation does the positive coupling 60 disengage. This reliably prevents a situation in which the locking element 22 is not locked but the positive coupling 60 is disengaged. When the locking element 22 is opened, it is ensured in the opposite way that the positive coupling 60 engages first to block the grinder drive, but the grinder housing door 18, i.e. the cross bolts 26 in the locking sleeve 30, are still locked.Only at the very end of the opening rotational movement of the closure element 22, after the positive coupling 60 has already engaged, is the unlocked state of the closure element 22 shown in Fig. 8 achieved, in which the closure element 22 can be pulled out of the closure sleeve 30 again in order to pivot open the grinder housing door 18. A 90° circumferential groove 76 with ends 76a, 76b in the closure sleeve 30 forms a guide for the cross bolts 26 (Figs. 5-6). The groove 76 also has an adjustment with which the closure element 22 and thus the grinder housing door 18 are pulled in.

[0127] The mechanical manipulation device 66 has movement stops on both sides for the locked or unlocked state of the grinder drive lock 74, which in the present example are provided by the linear guide 46.

[0128] When the grinder housing door 18 is fully opened, the user gains axial access to the grinding chamber 82 and the rotor grinder 84 arranged therein, which has a cutting rotor 86 rotating coaxially to the drive axis X and a plurality of axially extending stationary counter-blades 88 arranged around the cutting rotor 86. The cutting rotor 86 is preferably mounted on the drive shaft and axially screwed in place, and is driven via a positive-locking element. When the grinder housing cover 18 is fully opened, the user can pull the cutting rotor 86 axially off the drive shaft and out through the axial user access opening 94. During operation, the cutting rotor 86 rotates and the material to be ground is fed via the filling funnel 24 through the radial material filling opening 25 to the rotor grinder 84 and is comminuted by cutting action between the rotor cutting edges 90 of the cutting rotor 86 and the stationary counter cutting edges 88.The crushed ground material then trickles down through a sieve 98 into a collecting container 99.

[0129] Referring to Figs. 18-22, a laboratory mill 1 in the form of a knife mill comprises a grinding vessel 17, the interior of which defines the grinding chamber 82 and which stands on a lower part 12a of a device housing 12. The drive motor (not shown here) is housed in the device housing 12 and, via a vertical drive shaft, drives a grinding rotor 86 in the form of a rotor knife (not shown) arranged in the grinding chamber 82 of the grinding vessel 17. Such knife mills are generally known to those skilled in the art (cf. PULVERISETTE® 11, www.fritsch.de).

[0130] The space around the grinding vessel 17 can be closed by the safety cover 19, in this example in the form of a pivoting safety hood, so that the grinding vessel 17 is safely enclosed by the device housing 12. The grinding vessel 17 can also have an inner cover 104, which, however, does not have to fulfill a safety function. When the safety cover 19 is closed, as in the cutting mill, the closure element 22 engages the closure sleeve 30, couples to the mechanical manipulation device 66, thus closing the mechanical manipulation chain 65, is locked to the housing, and actuates the grinding mechanism drive lock 74 via the mechanical manipulation chain 65. Otherwise, the mechanical manipulation chain 65 and the grinding mechanism drive lock 74 function as in the cutting mill shown in Figs. 1-17. To avoid repetition, reference is made to the description there, which is hereby incorporated.

[0131] Referring to Figs. 23-28, a knife mill can also be provided with a safety lid 19, which securely closes the upper opening of the grinding vessel 17 but leaves the periphery of the grinding vessel 17 free. The manipulation device 66 can, for example, be accommodated laterally in a tower-like housing part 106. Safety is ensured by the safety lid 19, which interacts with the grinding mechanism drive lock 74, as in the cutting or knife mill shown in Figs. 1-22. Otherwise, the mechanical manipulation chain 65 and the grinding mechanism drive lock 74 function as in the cutting or knife mill shown in Figs. 1-22. To avoid repetition, reference is made to the description there, which is hereby incorporated.

[0132] It will be apparent to those skilled in the art that the above-described embodiments are to be understood as examples and that the invention is not limited to them, but can be varied in many ways without departing from the scope of the claims. Corresponding components of the exemplary cutting mill and knife mill are interchangeable, with the safety cover 19 of a knife mill or impact mill being functionally equivalent to the

[0133] Grinder housing door 18 corresponds to a cutting mill, cross-beater mill, or disc mill. Furthermore, it is evident that the features, regardless of whether they are disclosed in the description, the claims, the figures, or otherwise, also individually define essential components of the invention, even if they are described together with other features.

Claims

Laboratory mill (1) for grinding material, in particular designed as a cutting mill, impact mill, disc mill, knife mill or impact mill, comprising a device housing (12), a grinding unit housing (16) and / or a grinding vessel (17), a grinding chamber (82) in the grinding unit housing (16) or in the grinding vessel (17), wherein a grinding unit (84) can be arranged in the grinding chamber (82) with which the material is ground, and wherein the grinding unit housing (16) or the grinding vessel (17) has a user access opening (94), a grinding unit housing door (18) or a safety cover (19) for closing the user access opening (94), wherein the grinding unit housing door (18) or the safety cover (19) has an open and a closed state, wherein the user can access the grinding unit housing in the open state (18) or the safety cover (19).the user has access to the grinder (84) through the user access opening (94) of the safety cover (19), a grinder drive (2, 4) for driving the grinder (84), wherein the grinder housing door (18) or the safety cover (19) has a locking element (22) with which the grinder housing door (18) or the safety cover (19) can be locked in the closed state, and wherein the laboratory mill (1) has a mechanical grinder drive locking mechanism (74). Laboratory mill (1) according to claim 1, wherein the mill drive locking mechanism (74) is actuated by the locking element (22) and the locking element (22) locks the mechanical mill drive locking mechanism (74) when the locking element (22) is opened, thereby blocking the mill drive (2, 4) and / or the locking element (22) unlocks the mechanical mill drive locking mechanism (74) when the locking element (22) is closed, thereby releasing the mill drive (2, 4).

3. Laboratory mill (1) according to one of the preceding claims, wherein a mechanical manipulation device (66) is included and the locking element (22), the mechanical manipulation device (66) and the mill drive lock (74) form a mechanical manipulation chain (65) when the mill housing door (18) or the safety cover (19) is closed and wherein the movement of the locking element (22) is mechanically transmitted via the mechanical manipulation chain (65) to the mill drive lock (74) in order to lock and / or unlock the mill drive lock (74).

4. Laboratory mill (1) according to one of the preceding claims, wherein when the locking element (22) is opened, the mechanical mill drive locking mechanism (74) is locked first and blocks the mill drive (2, 4), and the unlocking of the mill housing door (18) or the safety cover (19) is mechanically blocked by the locking element (22) as long as the mechanical mill drive locking mechanism (74) is not yet locked, and / or wherein when the locking element (22) is closed, the mill housing door (18) or the safety cover (19) is locked first, and only after the mill housing door (18) or the safety cover (19) has been locked is the mechanical mill drive locking mechanism (74) unlocked and releases the mill drive (2, 4).

5. Laboratory mill (1) according to one of the preceding claims, wherein the mill drive comprises a drive motor (4) and a drive shaft (2) which is connected to the mill (84) to drive the mill (84) and wherein the mechanical mill drive locking mechanism (74) engages the drive shaft (2) and mechanically blocks the rotation of the drive shaft (2) when the mill housing door (18) or the safety cover (19) is not locked.

6. Laboratory mill (1) according to one of the preceding claims, wherein the mechanical mill drive locking mechanism (74) has a positive-locking coupling (60) which, in the disengaged state, releases the mill drive (2, 4). and, in the engaged state, positively blocks the mill drive (2, 4), wherein the positive-locking coupling (60) comprises, in particular, a stator coupling part (56) connected to the device housing (12) and a rotor coupling part (58) connected to the rotating parts of the mill drive and / or the mill (84), and wherein, in the positively engaged state, the stator coupling part (56) and the rotor coupling part (58) positively block the rotation of the mill (84). Laboratory mill (1) according to claim 6, wherein the positive-locking coupling (60) is engaged by axial displacement of the The stator coupling part (56) and / or the rotor coupling part (58) engages and disengages to lock and unlock the mill drive locking mechanism (74). Laboratory mill (1) according to claim 6 or 7, wherein the positive-locking coupling (60) comprises a stator coupling ring (57) and a rotor coupling ring (59) arranged around the drive shaft (2), the stator coupling ring (57) being attached to the device housing (12), the drive shaft (2) rotating in the stator coupling ring (57) when the coupling (60) is disengaged, and the rotor coupling ring (59) being attached to the drive shaft (2). Laboratory mill (1) according to one of the preceding claims, wherein a mechanical manipulation device (66) is included to which the locking element (22) couples when the mill housing door (18) or the safety cover (19) is closed and which controls the movement of the locking element (22) when locking and unlocking the mill housing door (18) or the safety cover (19).of the safety cover (19) mechanically transmits to the mill drive locking mechanism (74). Laboratory mill (1) according to claim 9, wherein the locking element (22) and the mechanical manipulation device (66) have complementary coupling elements (34, 36) which couple to each other when the mill housing door (18) or the safety cover (19) is closed and / or when the. The grinding mill housing door (18) and the safety cover (19) are decoupled from each other, wherein, in the coupled state, the movement of the locking element (22) is mechanically transmitted via the coupled coupling elements (34, 36) and the mechanical manipulation device (66) to the grinding mill drive locking mechanism (74) in order to unlock the grinding mill drive locking mechanism (74) when the locking element (22) is closed and release the grinding mill drive (2, 4) and / or to lock the grinding mill drive locking mechanism (74) when the locking element (22) is opened and block the grinding mill drive (2, 4). Laboratory mill (1) according to one of the preceding claims, wherein the locking element (22) comprises a key (28) which engages in a locking sleeve (30) and, by turning the key (28) in the locking sleeve (30), decouples the grinding mill housing door (18) and the safety cover (19).The safety cover (19) is locked and unlocked, and the unlocking and locking of the mill drive lock (74) is actuated. Laboratory mill (1) according to one of the preceding claims, wherein a transverse slide (44) is included and the actuation of the locking element (22) causes a transverse displacement of the transverse slide (44). Laboratory mill (1) according to claim 12, wherein the mechanical manipulation device (66) comprises a manipulator shaft (38) and an eccentric (40) connected to the manipulator shaft (38), wherein the manipulator shaft (38) is rotated by the locking element (22) and the eccentric (40) converts the rotational movement into a transverse displacement of the transverse slide (40).Laboratory mill (1) according to one of the preceding claims, comprising a control device and an electrically activatable holding device (72), and the control device activating the holding device (72) when the laboratory mill (1) is in operation, wherein the activated holding device (72) protects the mechanical. manipulation device (66) holds and prevents the locking element (22) from being moved by holding it, and / or wherein the control device deactivates the holding device (72) when the mill drive (2, 4) is stationary.

15. Laboratory mill (1) according to one of the preceding claims, wherein the movement of the closure element (22) when opening the closure element (22) is transmitted by rigid mechanical coupling via the mechanical manipulation device (66) to the mill drive locking mechanism (74) in order to engage the positive-locking coupling (60) and to lock the mill drive locking mechanism (74) and / or wherein the movement of the closure element (22) when closing the closure element (22) is transmitted via the mechanical manipulation device (66) to the mill drive locking mechanism (74) in order to unlock the mechanical mill drive locking mechanism (74) and wherein the disengagement of the positive-locking coupling (60) is effected by spring force (70).

16. Laboratory mill (1) for grinding material, in particular according to one of the preceding claims and in particular designed as a cutting mill, impact mill or disc mill, comprising a device housing (12) with a grinding unit housing (16), a grinding chamber (82) in the grinding unit housing (16), wherein a grinding unit (84) can be arranged in the grinding chamber (82) with which the material is ground, and wherein the grinding unit housing (16) has a user access opening (94), a grinding unit housing door (18) for closing the user access opening (94), wherein the grinding unit housing door (18) has an open and a closed state, wherein in the open state of the grinding unit housing door (18) the user has access to the grinding unit (84) through the user access opening (94), a grinding unit drive (2, 4) for driving the grinding unit (84), wherein the grinding unit housing door (18) has a door lock (22'),with which the mill housing door (18) can be locked in the closed state and wherein the laboratory mill (1) has a mechanical mill drive locking mechanism (74), A laboratory mill (1) for grinding material, in particular according to one of the preceding claims and in particular designed as a knife mill or impact mill, comprising a housing (12) and a grinding vessel (17), a grinding chamber (82) in the grinding vessel (17), wherein a grinding mechanism (84) with a grinding rotor can be arranged in the grinding chamber (82) with which the material is ground, and wherein the grinding vessel (17) has a user access opening (94), a safety cover (19), wherein the safety cover (19) has an open and a closed state, wherein in the open state the safety cover (19) allows the user access to the grinding rotor through the user access opening (94), a grinding drive (2, 4) for driving the grinding rotor, wherein the safety cover (19) has a locking element (22),with which the safety cover (19) can be locked in the closed state and wherein the laboratory mill (1) has a mechanical mill drive locking mechanism (74).

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