Laboratory mill, in particular rotor or centrifugal mill

Abstract

The invention relates to a laboratory mill (1) for grinding material, in particular a rotor or centrifugal mill, comprising: a housing (30) forming a lower motor compartment (134) and an upper grinding chamber (98), an electric drive motor (102) with a motor shaft (104) arranged in the lower motor compartment (134) of the housing (30), a grinding assembly (74) that can be inserted into the upper grinding chamber (98), which has a grinding rotor (52) that can be rotated by the drive motor (102), a stationary annular counter element (54) that can be arranged around the grinding rotor (52), and a sample collection container (56), wherein the grinding assembly (74) has a central rotor chamber (62) arranged radially inside the stationary annular counter element (54) and a peripheral annular sample collection chamber arranged radially outside the stationary annular counter element (54). (64) defines,an electric cooling fan (114) arranged in the area of ​​the lower motor compartment (134), which generates a cooling airflow (138) that flows along the electric drive motor (102) to cool the electric drive motor (102), a control device (142) for controlling the grinding process, and a user input device (40) via which the user can input grinding parameters for the grinding process, wherein the control device (142) is configured to control the grinding process in response to the grinding parameters entered by the user and wherein the control device (142) is configured to control the electric cooling fan (114) independently of the drive motor (102).

Description

Field of invention

[0001] The invention relates to a laboratory mill for grinding material, in particular a rotor or centrifugal mill, which effectively grinds the material by impact, blow, and / or shear action using a rotating grinding rotor, which is surrounded in an annular sample collection container by a stationary annular counter element, e.g. in the form of an annular sieve, an annular impact bar or an annular counter blade insert. Background and general description of the invention

[0002] Rotor mills, sometimes also called rotor high-speed mills or centrifugal mills, typically operate with a grinding rotor rotating around a vertical axis, surrounded by a stationary, ring-shaped counter element. The shape and design of the rotor can vary depending on the application. The ring-shaped counter element can be, for example, a ring screen, a so-called impact bar, or a ring-shaped counter-blade insert. The shape and size of the screen perforations can be selected according to requirements. The impact or cutting geometry of the rotor is typically located in the radially outer region of the rotor diameter. In a commonly used grinding assembly with an impact rotor and ring screen, the rotor typically consists of a horizontal circular base plate with a plurality of vertical impact teeth extending around its peripheral edge, parallel to the axis of rotation. These impact teeth thus form, for example...A ring-shaped colonnade, coaxial to the axis of rotation, is located in the radial outer area of ​​the rotor. Comminution occurs, for example, through impact, blow, and / or shear action by the impact teeth in the peripheral ring-shaped outer region of the rotor when it rotates at high speed around the vertical axis of rotation. The rotor's impact teeth thus collectively form a coaxial cylindrical shell within which the material to be ground is comminuted. This cylindrical shell of the impact teeth is directly surrounded by the cylindrical ring screen with a relatively small annular gap between them, so that the material to be ground is comminuted directly against the cylindrical inner surface of the ring screen and / or between the impact teeth and the ring screen. Once the material has reached a sufficient fineness, it can exit radially outwards through the perforations of the ring screen.The rotor and the ring sieve are arranged in a collection container, which forms a collection chamber surrounding the ring sieve in a ring shape, in which the crushed material exiting radially outwards through the sieve perforation is collected.

[0003] The collection container is typically sealed with a separate inner lid or collection container lid. The assembly of the collection container and inner lid, possibly together with the ring sieve and / or the rotor, forms an interchangeable grinding unit that can be inserted into the instrument housing and is sometimes also referred to as a cassette or interchangeable cassette. The rotor is mounted axially on the shaft of an electric drive motor. Typically, the drive motor for the rotor is installed vertically in the laboratory mill. This allows the user to feed the sample from above through a hopper and place it directly onto the rotating rotor. The short feed path reduces sample carryover. Furthermore, it keeps the number of components to a minimum and facilitates cleaning after grinding.The grinding unit is inserted into an upper section of the device housing, which is then closed for the grinding process with a housing cover, such as a hinged hood. For user safety reasons, the grinding process can only be started when the hood is locked.

[0004] Such rotor mills are described, for example, in DE 100 22 849 A1, DE 100 66 027 A1, DE 10 2012 010 065 A1, DE 20 2012 013 666 U1 and DE 20 2012 013 667 U1, which are hereby incorporated by reference.

[0005] Examples of rotor (high-speed) mills are the Pulverisette® < 14 classic line and the Pulverisette® < 14 premium line of the applicant, which are presented on its website www.fritsch.de, cf. www.fritsch.de / probenaufbereitung / mahlen / rotor-schlagmuehlen / details / produkt / pulverisette-14-classic-line / and www.fritsch.de / probenaufbereitung / mahlen / rotorschlagmuehlen / details / produkt / pulverisette-14-premium-line / . The descriptions, brochures, instructions, etc. contained on or downloadable from the applicant's website are hereby incorporated by reference as further background information on rotor and centrifugal mills into the subject matter of this disclosure.

[0006] During the grinding process, process heat is generated by the electrical components in the device, particularly by the electric drive motor, but also by electrical components in the vicinity of the drive motor, which continuously generate process heat. Some conventional rotor or centrifugal mills have a fan wheel coupled to the motor shaft at the lower end of the drive motor to cool it. This has proven to be improvable within the scope of the present invention, which is why the inventors have focused their efforts there.

[0007] It is an object of the invention to provide a laboratory mill for grinding material, in particular a rotor or centrifugal mill, which enables gentle grinding of the material in a laboratory mill with high grinding capacity.

[0008] Another aspect of the object of the invention is to provide a laboratory mill for grinding material, in particular a rotor or centrifugal mill, which is convenient and time-efficient for the user and requires little cleaning.

[0009] Another aspect of the object of the invention is to provide a laboratory mill for grinding materials, in particular a rotor or centrifugal mill, which enables effective grinding of a wide variety of even difficult materials, especially plastics that tend to vitrify.

[0010] The object of the invention is achieved by the subject matter of the independent claims. Advantageous embodiments of the invention are defined in the dependent claims.

[0011] According to one aspect of the invention, a laboratory mill for crushing or grinding materials is provided, which in particular belongs to the category of rotor or centrifugal mills. According to another aspect of the invention, the rotor or centrifugal mill comprises a housing divided into two functional areas: a lower motor compartment, which houses a drive motor with its motor shaft and optionally other electrotechnical components, such as power supplies, fans, a control unit, etc., and an upper grinding compartment, which houses a grinding assembly as an interchangeable grinding mechanism and in which the grinding process is carried out. The upper grinding compartment in particular has an intermediate floor that separates the upper grinding compartment from the lower motor compartment. The intermediate floor forms a partition between the upper grinding compartment and the lower motor compartment.

[0012] The grinding assembly can be inserted into and removed from the upper grinding chamber by the user, for example, to remove the ground material, to work with different grinding assemblies, and to clean the grinding assembly. The grinding assembly comprises a grinding rotor, which can be driven by the drive motor, and a stationary, annular counter-element arranged coaxially and, in particular, directly around the grinding rotor. The grinding rotor has, for example, an annular array or annular colonnade of a plurality of vertical impact teeth in its peripheral edge region. The stationary, annular counter-element interacting with the grinding rotor can, for example,The grinding assembly may be designed as a ring screen, annular impact bar, or annular counter-blade insert, and surrounds the annular impact tooth array in a ring shape, so that material fed into the grinding rotor is accelerated outwards by centrifugal force and is comminuted in the peripheral edge region of the grinding rotor by the impact teeth or in an annular gap between the impact teeth and the stationary annular counter-element, particularly by means of impact, blow, and / or shear action. The grinding assembly also includes an annular sample collection container, which may, in particular, have a peripheral circumferential ring wall and an annular base with a central hole. In the installed state, the annular base of the sample collection container extends above the intermediate floor that separates the upper grinding chamber from the lower motor chamber.

[0013] The grinding assembly, or rather the interior of the sample collection container, forms a central rotor chamber arranged radially inside the stationary annular counter-element, in which the grinding rotor rotates, and a peripheral annular sample collection chamber arranged radially outside the stationary annular counter-element, in which the ground material can be collected after grinding. The stationary annular counter-element delineates the central rotor chamber from the peripheral annular sample collection chamber, particularly in an annular fashion. In other words, the stationary annular counter-element forms a circumferential inner boundary, the peripheral annular wall a circumferential outer boundary, the bottom of the sample collection container a lower boundary, and the container lid an upper boundary of the peripheral annular sample collection chamber.

[0014] During operation of the laboratory mill, the comminution rotor rotates in the central rotor chamber, driven by the electric drive motor, such that the material to be ground, which is fed into the central rotor chamber, is comminuted by impact, collision and / or shear action by the comminution rotor, in particular in the form of a percussion rotor or impact rotor or cutting rotor, and / or between the comminution rotor and the stationary annular counter element, in particular in the form of an annular sieve, an annular impact bar or an annular counter blade insert, and the comminutioned material passes radially outwards through the stationary annular counter element into the peripheral annular sample collection chamber.

[0015] The laboratory mill also includes an electric cooling fan located in the area of ​​the lower motor compartment, which generates a directed cooling airflow that flows particularly axially along the electric drive motor in order to cool the electric drive motor effectively.

[0016] The electric cooling fan is located particularly below the electric drive motor and blows the cooling airflow upwards in an axial direction around the circumference of the electric drive motor.

[0017] The laboratory mill also includes a control unit, e.g. with a microprocessor and a program control for controlling the grinding process, as well as a user input device via which the user can enter grinding parameters for the grinding process, such as grinding duration, rotor speed, pauses, etc., so that the program control can automatically control the grinding process in response to the grinding parameters entered by the user.

[0018] The cooling fan is designed as an electric cooling fan, wherein the control device or the program control is designed to control the electric cooling fan independently of the drive motor, e.g. to continue operating the cooling fan even when the drive motor, i.e. the grinding process, has already stopped.

[0019] The heat generated in a laboratory mill can be divided into process heat from the electrical components and the heat of comminution. The heat of comminution is primarily caused by the impact and shearing of the material being ground. The conversion of the supplied energy into heat is undesirable for many applications of a rotor or centrifugal mill. Increasing temperatures during the grinding process can cause samples to develop negative properties or even become completely unusable. For example, some plastics can no longer be ground above a certain glass transition temperature because the softened sample material clogs the sieve openings. Certain components of organic samples can be destroyed when certain temperatures are exceeded. These problems increase with higher grinding rates. The present invention can advantageously at least mitigate them.

[0020] If the components of a rotor (high-speed) mill reach or exceed a certain temperature, pauses are also incorporated during which the heat is dissipated to the environment. These pauses can be advantageously shortened with the present invention.

[0021] When the grinding process of a sample into milled material is completed in a conventional rotor or centrifugal mill and the drive motor is stopped, the active cooling also stops. In contrast, an independently controlled or powered cooling fan can advantageously be used to control a cooling run-on period, which can be incorporated into a Standard Operating Procedure (SOP). Among other things, the waiting time before the user can remove the grinding assembly can be reduced if the components continue to be actively cooled for a certain period after the drive motor has stopped.

[0022] Furthermore, the rotational speed of a rotor or centrifugal mill can be variable. In conventional rotor mills, where the fan is mechanically coupled to the drive motor's shaft, the fan's speed depends on the motor shaft's speed. For example, if such a conventional laboratory mill is operated at 6000 rpm, the fan will rotate at the same speed and circulate less warm air than at the drive motor's maximum speed, which may exceed 20,000 rpm. By decoupling these components, the cooling fan can be operated continuously at its maximum power, independent of the drive motor's speed.

[0023] Advantageously, the cooling effect generated by the cooling fan can be provided independently of the operation and speed of the drive motor. In particular, maximum cooling capacity can be used while the laboratory mill is not operating at maximum speed, or additional active cooling capacity can be provided before or after the milling process and / or during milling breaks.

[0024] Thus, the present invention advantageously enables gentle comminution of the material to be ground at a reduced temperature. Even problematic plastics can be ground more effectively. In particular, vitrification and the resulting clogging of, for example, the ring sieve can be avoided or at least reduced. Therefore, effective grinding can be ensured, and the cleaning effort required for the grinding assembly can also be reduced.

[0025] If, as in this case, the fan wheel is decoupled from the drive motor and the cooling fan can be operated independently as a separately powered unit, a further advantage can be achieved compared to conventional rotor or centrifugal mills with a fan wheel mechanically coupled to the motor shaft. Decoupling the fan wheel from the drive motor shaft eliminates moving mass from the system that provides the grinding energy. This also reduces the load on the drive motor, which in turn reduces heat generation. Furthermore, a larger proportion of the motor's power can potentially be directed into the grinding process.

[0026] Preferably, the device housing has a housing cover, e.g., in the form of a hinged hood, such that the grinding chamber can be sealed off from the environment by the housing cover. More preferably, the sample collection container has its own separate collection container lid within the grinding chamber, which can be closed both inside and outside the grinding chamber. Thus, the sample collection container, sealed with the collection container lid, forms a cassette that can be inserted into and removed from the grinding chamber as a unit, possibly together with the grinding rotor and / or the stationary annular counter-element. Therefore, such a cassette of a rotor or centrifugal mill is sometimes also referred to as an interchangeable cassette.

[0027] The housing cover preferably has an axial central filling funnel. Furthermore, the collection container cover preferably has a central opening into which the lower end of the filling funnel opens, so that the user can feed material to be ground from outside the laboratory mill into the rotor chamber or onto the rotating grinding rotor during operation, either through the filling funnel and / or through the central opening in the collection container cover, particularly for the continuous feeding and grinding of material. The filling funnel can seal against the collection container cover when the housing cover is closed for the grinding process, preventing the material from escaping outside the sample collection container during feeding.

[0028] The program control is preferably configured to automatically switch the cooling fan on and off independently of the drive motor. Optionally, the program control is configured to control the fan speed of the cooling fan independently of the drive motor speed.

[0029] Preferably, the laboratory mill has a memory and is configured to store a run-on time interval in the memory. The program control is configured to allow the cooling fan to continue running for the duration of the run-on time interval after the drive motor is switched off, and only to switch off the cooling fan automatically after the run-on time interval has elapsed. Alternatively or additionally, a temperature control can be provided, wherein the program control is configured to allow the electric cooling fan to continue running in a temperature-controlled manner after the drive motor is switched off, e.g., until a predefined temperature threshold is undershot. The temperature measurement for the temperature control can be carried out, e.g., in the upper grinding chamber, particularly in the area of ​​the sample collection container, and / or at the drive motor.Such post-cooling is particularly advantageous in a high-performance rotor or centrifugal mill and allows for a shorter waiting time for the user to remove the sample collection container from the rotor or centrifugal mill.

[0030] Preferably, the program control is configured to process a run-on command entered by the user via the user input device and, in response to this command, to allow the cooling fan to continue running for a specified run-on time interval after the drive motor has stopped, and only to switch off the cooling fan automatically after this run-on time interval has elapsed. Preferably, the program control is configured so that the user can enter the duration of the run-on time interval via the user input device. Advantageously, the user can decide, depending on the grinding task, whether and, if so, how much run-on cooling is useful at the end of the grinding process or during grinding breaks.

[0031] According to a preferred embodiment, the laboratory mill has a first temperature sensor in the grinding chamber, in the area of ​​the sample collection container, which detects the temperature of the sample collection container and / or the material being ground during and / or after the grinding process. The laboratory mill may have a second temperature sensor on the drive motor, which detects the temperature of the drive motor during and / or after the grinding process. The program control is preferably configured to read the first and / or second temperature sensor during and / or after the grinding process in order to obtain temperature readings from the sample collection container or the material being ground and / or the drive motor during and / or after the grinding process and to display these readings to the user and / or to use them as a control variable for the drive motor and / or the electric cooling fan.

[0032] For example, the program control can use the temperature measurements as actual values ​​to control the grinding process, e.g. to stop or to regulate the speed of the drive motor, and / or to control the overrun and / or to regulate the speed of the electric cooling fan.

[0033] According to a preferred embodiment, the drive motor with a vertically extending motor shaft is installed in the lower motor compartment. The motor housing of the drive motor can have an axially and annularly extending motor housing shell. The cooling fan is preferably arranged below the drive motor, particularly coaxially to the vertically extending motor shaft, but decoupled from the motor shaft, and the cooling fan generates a substantially vertical upward flow of cooling air, which is guided axially within the motor housing shell and / or along an outer surface of the motor housing shell to effectively cool the drive motor.

[0034] Preferably, at least one axial first cooling air channel extends along the circumference of the electric drive motor in the axial direction. The axial first cooling air channel has a lower cooling air inlet opening at a lower end of the electric drive motor, through which the cooling airflow generated by the electric cooling fan is blown into the axial first cooling air channel. The axial first cooling air channel has an upper cooling air outlet opening at the upper end of the electric drive motor, through which the cooling airflow exits the axial first cooling air channel.

[0035] In other words, the electric drive motor preferably comprises a motor housing with a motor housing jacket that extends radially around the motor shaft and axially along the motor shaft. The axial first cooling air channel is preferably arranged in or on the motor housing jacket of the electric drive motor and is in thermal contact with the motor housing jacket, so that the cooling air flow in the axial first cooling air channel cools the motor housing jacket.

[0036] In other words, preferably at least one axial first cooling air channel is provided in or on the motor housing shell, extending axially from bottom to top, in particular from the cooling fan to the area of ​​the intermediate floor between the lower motor compartment and the upper grinding chamber. Within this at least one axial first cooling air channel, the cooling airflow from the cooling fan can thus be directed axially upwards along the motor housing shell within the first cooling air channel. Preferably, the at least one axial first cooling air channel comprises a plurality of axial first cooling air channels arranged at various circumferential positions on the motor housing shell. This advantageously allows for particularly effective cooling of the drive motor.

[0037] Preferably, the at least one axial first cooling air channel is essentially designed as a closed cooling air tube, which extends radially outside the rotating motor parts but within the motor housing shell or axially around the motor housing shell.

[0038] Preferably, the device housing has at least one second cooling air duct extending from the lower motor compartment into the upper grinding chamber, through which the cooling airflow from the lower motor compartment flows into the upper grinding chamber when the cooling fan is operating. Preferably, the at least one second cooling air duct comprises a plurality of second cooling air ducts extending parallel from the lower motor compartment into the upper grinding chamber, through which the cooling airflow from the lower motor compartment, or from the at least one axial first cooling air duct, or from the upper cooling air outlet opening, flows into the upper grinding chamber. The cooling airflow can effectively pass from the axial first cooling air duct(s) through the second cooling air duct(s) into the upper grinding chamber.

[0039] The at least one second cooling air duct extends through the intermediate floor from the lower motor compartment into the upper grinding chamber, so that the cooling airflow passes through the at least one second cooling air duct from the lower motor compartment into the upper grinding chamber. The at least one second cooling air duct has a lower cooling air inlet opening on the underside of the intermediate floor, through which the cooling airflow exiting the axial first cooling air duct enters the second cooling air duct. The second cooling air duct has an upper cooling air outlet opening on the upper side of the intermediate floor and / or below the annular sample collection container, through which the cooling airflow exits the second cooling air duct into the upper grinding chamber, in particular below the comminution rotor and / or the annular sample collection container.In other words, the cooling air flow preferably flows from the cooling air outlet opening of the axial first cooling air channel through the second cooling air channel into the upper grinding chamber, in particular under the annular bottom of the sample collection container.

[0040] In other words, the cooling airflow can be directed from the lower engine compartment and under the annular base of the sample collection container, particularly through at least one second cooling air duct.

[0041] Preferably, the cooling airflow generated by the same cooling fan successively cools first the electric drive motor, in particular the motor housing, and after passing through the intermediate floor into the upper grinding chamber, the annular sample collection container in the upper grinding chamber, in particular the annular bottom of the sample collection container.

[0042] Advantageously, the sample collection container can also be cooled effectively in this way. Furthermore, the same cooling air successively cools first the drive motor and then the sample collection container, which is advantageously adapted to the heat generation of the rotor or centrifugal mill.

[0043] The axial first cooling air duct can also be designed as a cooling air guide tube that surrounds the electric drive motor in a ring shape. Such a cooling air guide tube can also be provided in or on the motor housing in addition to one or more smaller diameter cooling air ducts, and can surround the motor housing, including the cooling air ducts, in a ring shape. In other words, as an alternative or in addition to the at least one axial first cooling air duct in or on the motor housing, a cooling air guide tube, e.g., with a rectangular cross-section, can be installed coaxially around the drive motor in the lower motor compartment. The cooling air guide tube can extend axially in a ring shape around the electric cooling fan and / or radially spaced around the drive motor, so that an annular space extending axially and in a ring shape around the drive motor is formed between the motor housing and the cooling air guide tube.The annular space can form a cooling air duct such that the cooling airflow is blown into the annular space by the cooling fan and guided axially upwards along the drive motor within the annular space, bounded radially inside and radially outside. The cooling air duct, if additionally present, is arranged, in particular, radially outside the at least one axial first cooling air duct(s). The cooling air duct can extend axially, in particular, from the bottom of the housing to the upper end of the lower engine compartment, in order to guide the cooling airflow along the entire axial extent of the engine housing. The cooling air duct system can therefore comprise at least two parallel cooling air paths in the lower engine compartment. The first cooling air path can be the axial first cooling air duct(s) in the engine housing shell, and the second cooling air path can, for example, be formed by the annular space between the engine housing and the cooling air duct.In other words, the cooling airflow can comprise at least two parallel cooling air streams. The first cooling air stream can be directed in the first cooling air path or in the axial first cooling air channels in the engine housing, and the second cooling air stream can be directed, for example, in the second cooling air path or in the annular space between the engine housing and the cooling air guide tube, particularly axially.

[0044] This advantageously allows for a particularly effective guidance of the cooling airflow from the cooling fan along the drive motor and, if necessary, into the upper grinding chamber.

[0045] The cooling airflow can have a volume flow rate of preferably at least 50 m³ / h, preferably at least 100 m³ / h, preferably at least 200 m³ / h, preferably in the range of 50 m³ / h to 1000 m³ / h, preferably in the range of 100 m³ / h to 500 m³ / h.

[0046] According to a preferred embodiment, the device housing has a horizontal intermediate floor between the upper grinding chamber and the lower motor chamber to largely prevent grinding dust or other contaminants from entering the lower motor chamber. The intermediate floor preferably has a central opening through which a rotor drive shaft extends vertically into the grinding chamber area, allowing the user to attach and detach the shredding rotor from the rotor drive shaft in the upper grinding chamber. The rotor drive shaft can, for example, be the motor shaft itself or an axial extension of the motor shaft. Thus, a direct drive is preferably formed. Preferably, the rotor drive shaft and the shredding rotor have complementary drive means, e.g.,Transverse bolts and a corresponding transverse groove are provided, such that the comminution rotor can be placed on the rotor drive shaft in the grinding chamber from above and can be driven by the complementary drive means from the rotor drive shaft in a rotating manner.

[0047] Preferably, a ring seal, in particular a labyrinth seal, is arranged around the rotor drive shaft between the shredding rotor and the drive motor, sealing the upper grinding chamber against the lower motor compartment. The labyrinth seal preferably comprises a lower, stationary labyrinth disc attached to the device housing. The counter-labyrinth can be formed directly on the underside of the shredding rotor. Preferably, the stationary labyrinth disc forms a cover plate of a dome structure that projects axially upwards into the upper grinding chamber.The sample collection container can have a corresponding central lower recess by means of which the sample collection container is placed over the dome structure, such that the stationary labyrinth disc is positioned within the central lower recess and above the bottom of the sample collection container when the sample collection container is inserted into the upper grinding chamber. The underside of the comminution rotor and the stationary labyrinth disc thus form an axial or axially extendable labyrinth seal. The stationary labyrinth disc and the underside of the comminution rotor each have complementary concentric labyrinth rings that interlock axially and seal radially, so that the comminution rotor is axially mounted onto the rotor drive shaft, thereby engaging the complementary labyrinth rings and bringing the comminution rotor into contact with the dome structure.

[0048] The labyrinth seal seals the rotor chamber and / or the peripheral annular sample collection chamber or the interior of the sample collection container against the lower motor chamber to prevent contamination of the motor chamber with ground material.

[0049] Beneath the labyrinth seal, at least one second cooling air channel can extend through the intermediate floor from the lower motor compartment into the upper grinding chamber and terminates beneath the sample collection container, or preferably beneath the dome structure. From beneath the dome structure, the cooling air flow can then be directed radially outwards beneath the base of the sample collection container. The cooling air flow can thus be directed, for example, from the motor housing and / or from the at least one axial first cooling air channel into the upper grinding chamber, particularly beneath the annular base of the sample collection container. If desired, the cooling air flow from the motor housing and / or from the at least one axial first cooling air channel can also be forced, if necessary, partially through the gaps in the labyrinth seal into the interior of the sample collection container. This prevents a counterflow against the ingress of fine grinding material through the labyrinth seal into the motor compartment.

[0050] The dome assembly preferably has an annular shell, on the upper end of which the stationary labyrinth disc is mounted, so that the dome assembly is particularly hat-shaped or truncated cone-shaped. The annular shell of the dome assembly can have openings leading from the interior of the dome assembly to the peripheral exterior. The cooling airflow, which is directed from at least one second cooling air duct into the interior of the dome assembly beneath the stationary labyrinth disc, can thus flow through the openings from the interior of the dome assembly into the upper grinding chamber, more precisely beneath the sample collection container, in order to cool it effectively.

[0051] The axial first cooling air duct(s) in the motor housing preferably transition in series with the second cooling air duct(s) between the lower motor compartment and the upper grinding chamber, so that the axial first cooling air duct(s) in the motor housing and the second cooling air duct(s) between the lower motor compartment and the upper grinding chamber form a common cooling airflow system, optionally with several parallel ducts, which may extend more or less continuously from the cooling fan to below the dome structure and into the upper grinding chamber, such that the cooling airflow is effectively directed from the cooling fan through the cooling airflow system along the drive motor and upwards into the upper grinding chamber. This allows the main heat-generating components of the rotor or centrifugal mill to be efficiently cooled successively with one and the same cooling airflow.In other words, the laboratory mill has a cooling air duct system in which the cooling airflow from the cooling fan is directed essentially axially upwards to below the labyrinth disc and then radially outwards to below the sample collection container. In other words, the at least one axial cooling air duct extending along the drive motor and the at least one secondary cooling air duct extending from the lower motor compartment into the upper grinding chamber form a serial cooling air duct system from the drive motor to the upper grinding chamber.

[0052] According to a preferred embodiment, the device housing has a housing cover, in particular a hood, with which the user seals the grinding chamber from the environment. The housing cover can have a locking mechanism, in particular a motorized one, which is controlled or monitored by the program control. The program control can be configured to automatically open the locking mechanism when the drive motor and / or the grinding rotor has come to a standstill, but while the cooling fan is still running. This allows, for example, the program control to release the locking mechanism or open the housing cover independently of the cooling fan's after-run operation.

[0053] Preferably, the program control can be configured to automatically open the housing cover at least partially after the drive motor is switched off, while the cooling fan is still running. This advantageously allows for effective post-cooling after the grinding process has ended.

[0054] In particular, the program control can be designed to open the housing cover only a crack, but not completely, after the drive motor is switched off, while the cooling fan is still running, so that the cooling airflow can escape from the grinding chamber into the environment through the crack. For this purpose, a spring-loaded catch can be incorporated between the device housing and the housing cover, which pushes the housing cover open a crack when the locking mechanism is released. This has the advantage, among others, of achieving improved post-cooling while preventing objects that the user may have placed on the housing cover during the grinding process from being ejected. Another advantage of the automatic opening a crack or the spring-loaded catch is that the user does not necessarily have to be present after the grinding process for the housing cover to open automatically. If desired, the rotor or...A centrifugal mill can be combined with a feed trough device, particularly a vibrating feed trough. The user can then fill the feed trough hopper and set an appropriate feed rate. The user can then leave the rotor or centrifugal mill and prepare the next batch during and after grinding. The rotor or centrifugal mill can automatically stop after a pre-programmed grinding time and subsequently open the housing cover slightly – even in the user's absence – for improved cooling.

[0055] Preferably, the device housing includes a base with ventilation openings or a ventilation grille directly below the cooling fan. This allows cool intake air to be drawn in from under the base of the device housing and directed vertically upwards along the motor housing by the cooling fan as a directed cooling airflow, and from there into the upper grinding chamber or under the base of the collection container. The cooling air can then exit from the upper grinding chamber into the environment. This cooling air routing advantageously utilizes the thermodynamic properties of the rotor or centrifugal mill design. In particular, during ventilation, the cooling air is guided past the following components: First, the cooling air is guided along the motor in the provided axial cooling air channels.Furthermore, the cooling air is directed under the labyrinth and the comminution rotor via the second cooling air channels. The cooling airflow then passes the collection vessel containing the comminuted sample and finally exits through openings in the housing, thus ensuring effective cooling of the sample collection container as well.

[0056] High grinding performance is made possible, in part, by effective cooling. The maximum speed of the drive motor and / or the grinding rotor can even be greater than or equal to 24,000 rpm. The motor power of the drive motor can be greater than or equal to 1 kW, preferably greater than or equal to 1.3 kW, or even preferably greater than or equal to 1.5 kW. Such high power is difficult, at least, to achieve with conventional rotor mills. In this case, the improved cooling effect of the present cooling concept advantageously enables high power output, thus facilitating high grinding performance.

[0057] According to another aspect of the invention, a laboratory mill for grinding material, in particular a rotor or centrifugal mill, is provided, which comprises: a device housing forming a lower motor compartment and an upper grinding compartment, an electric drive motor with a motor shaft arranged in the lower motor compartment of the device housing, a grinding assembly insertable into the upper grinding compartment comprising a comminution rotor rotatably driven by the drive motor, a stationary annular counter element arrangable around the comminution rotor, and a sample collection container, wherein the grinding assembly defines a central rotor chamber arranged radially within the stationary annular counter element and a peripheral annular sample collection chamber arranged radially outside the stationary annular counter element, an electric cooling fan arranged in the area of ​​the lower motor compartment which generates a cooling airflow, and a cooling air duct system.in which the cooling airflow from the cooling fan is directed along the electric drive motor and to below the sample collection container in order to cool the electric drive motor and the sample collection container. A laboratory mill with a conventional fan or impeller and the disclosed novel cooling airflow, possibly in combination with one or more of the further features disclosed herein, is therefore also said to be within the scope of the present application.

[0058] The invention also relates to a method for operating a laboratory mill or a rotor or centrifugal mill, comprising the following steps: Inserting the grinding assembly into the upper grinding chamber, closing the housing cover, entering a run-on time or a run-on command for the cooling fan into the user input device, entering a start command into the user input device, after stopping the drive motor, opening the housing cover while the electric cooling fan is still running, removing at least the sample collection container and the collection container cover from the upper grinding chamber, either while the electric cooling fan is still running or after stopping the electric cooling fan.

[0059] The invention will now be explained in more detail with reference to exemplary embodiments and the figures, whereby identical and similar elements are partially provided with the same reference numerals and the features of the different exemplary embodiments can be combined with one another. Brief description of the characters

[0060] They show: Fig. 1 a front view of an exemplary embodiment of a laboratory mill, Fig. 2 a side view from the right of the laboratory mill Fig. 1 Fig. 3 a three-dimensional representation of the laboratory mill made of Fig. 1 with exploded view of the grinding assembly, Fig. 4 a section from Fig. 3 Fig. 5 a three-dimensional representation of an exemplary internal structure of a laboratory mill, Fig. 6 a cross-sectional view along line 6-6 in Fig. 1 , Fig. 7 a cross-sectional view along line 7-7 in Fig. 2 , Fig. 8 a horizontal section along line 8-8 in Fig. 1 , Fig. 9 a cross-sectional view along line 9-9 in Fig. 8 , Fig. 10 a view of the underside of the laboratory mill made of Fig. 1 with partially hidden bottom grid, Fig. 11 a side view from the left of the laboratory mill Fig. 1 , Fig. 12 a sectional view along line 12-12 in Fig. 11, Fig. 13 an enlarged sectional view of the grinding assembly made of Fig. 12 , Fig. 14 a top view of the laboratory mill from Fig. 1 with the housing cover hidden, Fig. 15 a top view of the laboratory mill made of Fig. 1 with partially hidden housing cover, Fig. 16 a cross-sectional view along line 16-16 in Fig. 15 , Fig. 17a a detail enlargement from Fig. 16 , Fig. 17 a close-up with exploded view of the collection container lid sensor device, Fig. 18 a cross-sectional view along line 18-18 in Fig. 15 , Fig. 19a a detail enlargement from Fig. 18 Fig. 19: Enlarged detail view with exploded view of the housing cover sensor assembly; Fig. 20: A sectional view of a section of the laboratory mill made of Fig. 1 , Fig. 21 a partially cutaway three-dimensional view of the laboratory mill made of Fig. 1 , Fig. 22 a detail enlargement from Fig. 21 , Fig. 23 a close-up enlargement similar to Fig. 22 , seen from the front, Fig. 24 a cutaway view of the laboratory mill made of Fig. 1 with the housing cover slightly open, Fig. 25 a close-up detail from Fig. 24 , Fig. 26 a schematic functional sequence of a grinding process, Fig. 27 a cross-sectional view of another embodiment of the laboratory mill. Detailed description of the invention

[0061] The Figs. 1 to 4Figure 1 shows a laboratory mill 1, which in the present embodiment is designed as a rotor mill or so-called rotor high-speed mill. The rotor mill 1 has a housing 30, which includes a lower base housing 32 that can be placed on a laboratory table by means of feet 34. The housing 30, or the base housing 32, can be closed with a pivoting lid 36 on the top of the base housing 32. The lid 36 has a feed hopper 38 into which material to be ground can be fed into the rotor grinding mechanism during operation of the rotor mill 1. A user input device 40, e.g., in the form of a touch display 42 and a rotary knob 44, is located on the top of the base housing 32, via which the user can program and control the rotor mill 1.For example, the user can enter the grinding duration, speed, grinding pauses or other process parameters dependent on the material being ground or the grinding task via the 42-inch touch display and start the grinding process.

[0062] The rotor mill 50 comprises a comminution rotor 52 rotating about a vertical axis of rotation A, which is, for example, designed as a percussion rotor, and a stationary annular counter element in the form of an annular screen 54 in which the comminution rotor 52 rotates coaxially. The comminution rotor 52 and the annular screen 54 are positioned in a sample collection container 56 and divide the interior of the sample collection container 56 into a central rotor chamber 62, in which the comminution rotor 52 rotates and comminsulates the material to be ground, and a peripheral annular sample collection chamber 64, in which the comminuted material is collected. For the grinding process, the user feeds the sample or material to be ground axially into the central area of ​​the comminution rotor 52 via the material feed hopper 38. The material to be ground is accelerated radially outwards in the comminution rotor 52 by centrifugal force.In a peripheral ring region of the comminution rotor 52, there is an annular colonnade arrangement 58 consisting of a plurality of impact teeth 66, which comminute the material to be ground at high speed by means of impact, collision, and / or shear action. The material can also be partially comminuted between the impact teeth 66 and the annular screen 54. The comminuted material can then pass radially outwards through the openings (not shown) of the annular screen 54 and enter the annular sample collection chamber 64. Optionally, the comminuted material can also be extracted by a suction device (not shown) which can be connected to a suction port 70. The suction port 70 is clearly optional, and other grinding assemblies or sample collection containers 56 do not have a suction port; instead, the annular shell 56a of the sample collection container 56 is completely closed.

[0063] The annular sample collection container 56 is closed at the top with a collection container lid 72. The grinding assembly 74 is thus formed from the sample collection container 56, the collection container lid 72, and the impact rotor 52 and ring screen 54 arranged in the closed sample collection container 56. The sample collection container 56 can be removed from the rotor mill 1 with or without the attached collection container lid 72, for example, to handle the ground material outside the rotor mill 1 or to clean the grinding assembly. The collection container lid 72 has a central sample filling opening 78 into which the filling funnel 38 opens axially when the housing lid 36 is closed, in order to feed the ground material into the grinding rotor 52 during operation.

[0064] The grinding chamber 98 is bounded on the underside by an intermediate floor 96 as a partition to the lower motor chamber 134 and on the upper side by the hood-shaped housing cover 36. The grinding rotor 52 has concentric labyrinth rings 82 on its underside, which together with corresponding concentric labyrinth rings 84 of the labyrinth disc 80 form a disc-shaped labyrinth seal 86 (cf. Fig. 13 , 14When inserting the grinding assembly 74 into the rotor mill 1, the user can first place the labyrinth disc 80 onto an annular mantle 92, which projects coaxially from the intermediate floor 96 of the grinding chamber into the grinding chamber 98. The annular mantle 92 and the attached labyrinth disc 80 together form a central hat-shaped or truncated cone-shaped dome structure 94 on the intermediate floor 96 of the grinding chamber 98. The parts of the grinding assembly 74 can be placed onto the dome structure 94 in the grinding chamber 98, and then the grinding chamber is closed by folding and locking the housing cover 36 to start the grinding process.

[0065] Referring to the Fig. 6-14The rotor mill 1 has a drive motor 102, the motor shaft 104 of which runs vertically and forms the central axis A of the rotor mill 1. The shredding rotor 52 can be axially mounted onto a rotor drive shaft 106, which in the present embodiment can be the motor shaft 104 itself, and can be driven in a rotating manner by a transverse bolt 108, which is attached to a lower drive extension 112 of the shredding rotor 52 by means of a transverse groove 110.

[0066] An electric cooling fan 114 is positioned below the drive motor 102, preferably coaxially with the drive motor 102. The cooling fan 114 draws in fresh cooling air through a base plate 116 of the device housing 30 and generates a cooling airflow, schematically symbolized by arrows 138, which is directed vertically upwards towards the drive motor 102 and flows axially upwards along the drive motor 102. For this purpose, the base plate 116 has a bottom grille 118 below the cooling fan 114. The bottom grille 118 is spaced from the laboratory table on which the rotor mill 1 stands by the feet 34, in order to draw in fresh cooling air from the side under the base plate 116 and from there through the bottom grille 118 into the interior of the device housing 30, more precisely into the lower motor compartment 134, and blow it axially upwards towards the drive motor 102.

[0067] To generate a directed cooling airflow 138 axially along the drive motor 102, the drive motor 102 in this example has a motor housing 122, which defines vertical or axial first cooling air channels 124 in the exterior of the motor housing 122 or in a motor housing jacket 123. In this example, the motor housing 122 is essentially square in horizontal section and has, in particular, four vertical first cooling air channels 124 at its corners. These channels are aerodynamically aligned with the electric cooling fan 114 and directly receive the cooling airflow 138 directed vertically upwards by the cooling fan 114. Within the first cooling air channels 124, they direct the airflow upwards around the motor, thus enabling effective cooling of the drive motor 102. In other words, the cooling fan 114 blows the cooling air through cooling air inlet openings 124a into the first cooling air channels 124.In the present example, the volume flow rate of the cooling airflow is approximately 255 m³ / h.

[0068] In the present embodiment, the drive motor 102 with its motor housing 122 is installed in a vertically extending axial cooling air guide tube 126. The cooling air guide tube 126 surrounds the motor housing 122 at a radial distance, so that an annular space or gap 128 is formed between the drive motor 102 or the motor housing 122 and the cooling air guide tube 126. In the present example, the cooling air guide tube 126 has a rectangular cross-section. It is evident, however, that the cooling air guide tube can also have a different cross-sectional shape, e.g., round. Cooling air in the form of a directed cooling airflow 138 can also be guided axially upwards along the drive motor 102 through the annular space 128. In the present example, the annular space 128 surrounds the entire drive motor 102 in a ring shape, so that a relatively large cooling airflow 138 can be guided within it.the flow resistance in the space 128 is relatively small.

[0069] At the upper end of the drive motor 102, the cooling air flow 138 can exit from cooling air outlet openings 124b of the first cooling air ducts 124 and / or from the annular space 128 and enter cooling air inlet openings 132a of the second cooling air ducts 132. The second cooling air ducts 132 extend through the intermediate floor 96 from the lower motor compartment 134 into the upper grinding chamber 98. The upper grinding chamber and the lower motor compartment 134 are otherwise preferably separated by the intermediate floor 96, which forms a horizontal partition between the upper grinding chamber 98 and the lower motor compartment 134, in order to prevent contamination in the lower motor compartment 134.

[0070] Accordingly, the first cooling air ducts 124 and / or the annular space 128 surrounding the motor housing 122, together with the second cooling air ducts 132, form a common cooling air duct system or cooling air flow system, which extends from the cooling fan 114 on the base plate 116 of the device housing 30 up into the upper grinding chamber 98. The cooling fan 114 draws in cooling air through the base plate 116 from outside the device housing 30 and blows it into the cooling air duct system, which directs the cooling air flow 138 vertically and axially upwards along the drive motor 102 and from there through the horizontal intermediate floor 96 between the upper grinding chamber 98 and the lower motor compartment 134 into the upper grinding chamber 98. The cooling air from the upper grinding chamber 98 can escape to the outside into the environment through an outlet grille 120, e.g. in the housing cover 36 ( Fig. 20 ).

[0071] In other words, the total cooling airflow 138 in the lower engine compartment 134 comprises a first cooling airflow 138a in the axial first cooling air channels 124 in the engine housing 123 and a parallel second cooling airflow 138b in the space or annular space 128 between the engine housing 122 and the cooling air guide tube 126. The cooling airflows 138a and 138b are guided axially upwards along the drive motor 102 separately from each other by the cooling air channel system. In this example, both cooling airflows 138a and 138b are recombined in the upper region of the drive motor 102 and then flow together into the second cooling air channels 132, which are connected in series with it.

[0072] In particular, the cooling airflow 138 is directed from the second cooling air ducts 132 between the lower motor compartment 134 and the upper grinding chamber 98 under the sample collection vessel 56, specifically under its annular base 60. When the grinding assembly 74 is installed, the annular base 60 extends in a ring around the dome structure 94, on which the comminution rotor 52 rotates and is sealed by means of the labyrinth seal 86. For this purpose, the dome structure 94, or the annular shell 92 rising from the intermediate base 56, has, for example, elongated milled cooling air passage openings 136, which lead radially outwards from the interior of the dome structure 94 under the base 60 of the sample collection vessel 56. In other words, the cooling air flows from cooling air outlet openings 132b of the second cooling air channels 132 under the labyrinth disc 80 into the interior of the dome structure 94 under the labyrinth disc 80 and from there through the radial cooling air passage openings 136 ( Fig. 3 , 4) under the bottom 60 of the sample collection container 56. This allows for efficient cooling of both the drive motor 102 and the grinding assembly 74, and thus of the material being ground, during and, if necessary, after grinding.

[0073] The rotor mill 1 is controlled by a control unit 142 with a program controller. The control unit 142 is connected to the user input device 40, and the program controller receives and processes the grinding parameters entered by the user. The program controller of the control unit 142 controls, for example, the rotational speed of the rotor mill and the start and stop of the grinding process, monitors safety devices such as the locking mechanism of the housing cover 36, and, if necessary, monitors or controls a variety of other functions of the rotor mill 1. The program controller also controls the electric cooling fan 114, in particular its switching on and off. For example, the program controller can be configured to allow the electric cooling fan 114 to continue running with a run-on control after the grinding process has already ended, i.e., after the drive motor 102 has already stopped.The overrun control can be predefined as part of a standard operating procedure (SOP) and / or requested by the user as a parameter via the user input device 40, if required for the specific grinding task. This means that the user can, for example, enter the overrun command into the program control via the user input device 40, particularly before the start command for the grinding process, and, if necessary, also define the overrun time quantitatively. The rotor mill 1 then starts the drive motor 102, allowing the user to grind their sample. After the drive motor 102 stops, the program control automatically allows the cooling fan 114 to continue running for a predetermined overrun time to further cool the drive motor 102 and the sample collection container 56 after the grinding process has ended. This can be advantageous, among other things, for the subsequent handling of the grinding assembly 74. For example,Immediately after the drive motor 102 stops, the grinding assembly 74 may still be too hot to be removed from the device housing 30 by the user. Due to the run-on time and the associated post-cooling, which is automatically performed by the program control after the drive motor 102 stops, the user can, if necessary, attend to other tasks while the drive motor 102 and the sample collection container 56 continue to cool down, and this occurs more quickly than if only the housing cover 36 were opened. Furthermore, if necessary, the drive motor 102 can also be cooled further after the user has already removed the grinding assembly 74. This increases the efficiency of using the rotor mill 1.

[0074] In summary, the control unit 142 contains a program control which can control the electric cooling fan 114 independently of the grinding process or independently of the drive motor 102.

[0075] A first temperature sensor 144 can be arranged below the sample collection container 56, which determines the temperature of the sample collection container 56 and thus indirectly the temperature of the material being ground. A second temperature sensor (not shown) can measure the temperature of the drive motor 102. In this example, the drive motor 102 has three second temperature sensors, which are located directly in the windings U, V, and W. In this example, the second temperature sensors can only switch in binary mode, I / O. This means that if the temperature exceeds 135°C, the drive motor 102 is switched off. The program control can be configured to read the first and / or second temperature sensor and control the grinding process in response to the temperature readings from the first and / or second temperature sensor. For example, the program control can be configured to control an interval grinding process using the measured temperature values.The program control can be configured to automatically switch off the drive motor 102 when the temperature reading at the first and / or second temperature sensor exceeds a predefined temperature threshold value T1max or T2max, respectively, which is stored in a memory of the control unit. The program control then continues to operate the electric cooling fan 114, at least until the predefined threshold values ​​for the first and / or second temperature reading are no longer exceeded. This also increases the efficiency of mill operation, as it reduces the time required for the sample collection vessel 56, and thus the material being ground and / or the drive motor 102, to cool down sufficiently, for example, for handling the grinding container and / or for the next grinding process.

[0076] To further improve post-cooling, the housing cover 36 can be equipped with a pop-up mechanism 150 which, after the drive motor 102 stops, causes the housing cover 36 to pop open slightly, as shown in the Figs. 24, 25 is shown.

[0077] The housing cover 36 is held closed or locked, for example, by a motorized interlock 152. The motorized interlock 152 is controlled and monitored by the program control, so that the grinding process can only be released when the motorized interlock 152 of the housing cover 36 is in the closed safety position (see figure). Figs. 21-23 ).

[0078] After the drive motor 102 stops, the program control can automatically open the interlock 152. The housing cover 30 can include an actuator 154 that partially, but preferably not completely, opens the housing cover 36. This allows the laboratory mill 1 to automatically open the housing cover 36 partially, or to a gap, after the grinding process has finished, allowing the warmed cooling air to escape even more effectively from the upper grinding chamber 98. For this purpose, one or more actuators 154 are preferably provided in the area of ​​the cover hinges 158, e.g., one actuator 154 on each side of the housing cover 36. In the illustrated embodiment, the actuators 154 are designed as spring-loaded snap locks, which may not retract deeply enough to engage when the housing cover 36 is closed. As a result, the spring-loaded snap locks constantly press their roller 156 downwards, generating an opening force on the housing cover 36.To close the housing cover 36, the user pushes the cover downwards against the preload of the actuators 154. The motorized locking mechanism 152 then pulls the cover further and locks it in place, ensuring the grinding process can be started safely. Additionally, torsion springs (not shown) can be provided in the cover hinges 158 to assist in lifting the housing cover 36 with the feed hopper 38. Furthermore, spring-loaded rotor locking pins 162 can be provided in the housing cover 36 to mechanically block the grinding rotor 52 from starting if the user forgets to put the collection container cover 72 on. When the collection container cover 72 is placed on the sample receiving container 56, the spring-loaded rotor locking pins 162 bear against the cover and thus assist in lifting the housing cover 36.

[0079] The grinding process can therefore proceed as follows: With the housing cover 36 open, the user inserts the grinding assembly 74 into the upper grinding chamber of the rotor mill 1. First, the labyrinth disc 80 can be placed on top, and then the grinding rotor 52 can be mounted onto the rotor drive shaft 106, whereby the labyrinth rings 82 of the grinding rotor 52 engage axially with the labyrinth rings 84 of the labyrinth disc 80 to form the labyrinth seal 86. The ring-shaped counter-element, e.g., ring sieve 54, can then be placed around the comminution rotor 52, e.g., on an outer edge of the labyrinth disc 80. The sample collection container 56, with its central opening 57 in the base 60, can then be placed over the comminution rotor 52 and, if applicable, the ring sieve 54, whereby the sample collection container 56 is also placed over the dome structure 94 on the intermediate floor 96 of the inner grinding chamber 98.Finally, the collection container lid 72 can be placed on the sample collection container 56 and, if necessary, sealed with a ring seal 73 and an annular peripheral ring rim 75. For some grinding assemblies 74, a different insertion sequence may be required; for example, in some grinding assemblies, the grinding rotor 52 and / or the ring sieve 54 can be completely removed from the upper grinding chamber 98 and reinserted. The housing lid 36 is then closed or pivoted shut, with the lower end 39 of the filling hopper 38 engaging the central sample filling opening 78 of the collection container lid 72. Furthermore, the housing lid 36 is, if necessary, tightened and locked by the retaining clip 152.

[0080] The user can either pre-program the grinding parameters for several grinding tasks or do so individually before or after closing the housing cover 36. Parameters such as speed, grinding duration, grinding pauses, and the overrun itself, as well as any overrun time, can be programmed. The user then starts the grinding process and feeds the material to be ground through the feed hopper 38 into the interior of the grinding unit 74 towards the grinding rotor 52. When the grinding process is complete, the program control first stops the drive motor 102, but allows the cooling fan 114 to continue running for the programmed overrun time. Furthermore, after the drive motor 102 stops, the program control can automatically open the locking mechanism 152, allowing the cooling fan 114 to continue running even longer.By opening the locking mechanism 152, the actuators 154 can open the housing cover 56 slightly, thus further improving the efficiency of the post-cooling. When the post-cooling time has elapsed, the program control automatically stops the cooling fan 114.

[0081] Referring to the Figs. 15-19The laboratory mill 1 has a housing cover sensor device 202 between the base housing 32 and the housing cover 36, which monitors the closed state of the housing cover 36. A collection container cover sensor device 212 is provided between the housing cover 36 and the collection container cover 72, which detects the presence and / or correct seating of the collection container cover 72 on the sample collection vessel 56 within the upper grinding chamber 98 when the housing cover 36 is closed. In this example, both sensor devices 202 and 212 are designed as double spring contacts, which allow current flow by contacting a conductive surface. The first spring contacts 204 of the housing cover sensor device 202 are preferably arranged on a lower edge 36a, for example, in the front region of the housing cover 36 opposite the cover hinges 158 of the housing cover 30.When the housing cover 36 is swung shut, the spring contacts 204 come into contact with an electrically conductive counter plate 206, spring back slightly, and the circuit between the two spring contacts 204 is automatically closed via the counter plate 206 when the user closes the housing cover 36.

[0082] The sample container lid sensor device 212, or its second spring contacts 214, is preferably arranged on an inner surface 36b of the housing lid, specifically in the area of ​​the sample container lid 72. When the user closes the housing lid 36, the sample container lid sensor device 212 detects the presence or correct seating of the sample container lid 72 on the sample container 56, as the sensor device 212 comes within close proximity to the sample container lid 72. In this example, the spring contacts 214 automatically come into contact with a top surface 72a of the sample container lid 72 when the housing lid 36 is closed. The sample container 56, and in particular the sample container lid 72, preferably have an electrically conductive surface, for example, made of bare stainless steel sheet.This establishes a galvanic contact between the two spring contacts 214 of the collection container lid sensor device 212 and the upper surface 72a of the collection container lid 72. The program control monitors the current flow through the sensor devices 202 and / or 212 and detects whether the housing lid 36 is closed and / or whether the collection container lid 72 is present in the upper grinding chamber 98 and correctly positioned on the sample collection container 56. The program control is designed to enable the start of the grinding process or the drive motor 102 only when the housing lid sensor devices 202 signal the closed state and the collection container lid sensor device signals the enabled state. In this example, both sensor devices 202 and 212 are designed with spring contacts that allow current flow via galvanic contact.However, the sensor devices 202 and / or 212 may also include other sensor devices, such as optical sensors, an NFC sensor or reed contacts.

[0083] The collection container lid 72 preferably consists of an annular lid plate 72b surrounding the central filling opening 78 and a peripheral ring rim 72c that runs annularly around the lid plate 72b to center the collection container lid 72 on the sample collection container 56 and in which the ring seal 73, preferably in the form of an O-ring, is attached to seal against the upper ring rim 56a of the sample collection container 56. The collection container lid sensor device 212 is preferably arranged above the lid plate 72b, so that in the present embodiment the second spring contacts 214 automatically come into contact with the lid plate 72b when the housing lid 36 is closed.

[0084] If the housing cover sensor 202 signals neither a closed nor an open state, this constitutes safety-relevant information, so the program control prevents the drive motor 102 from starting, and the user cannot override this. The presence or absence of the collection container lid 72, however, does not represent a safety-relevant function, so the collection container lid sensor 212 does not represent any safety functions. Therefore, the program control can have an override function that allows the user to manually override the prevention of the drive motor 102 starting or the grinding process, for example, by entering an override command at the user input device 40.The advantage lies in the fact that the user can still operate the laboratory mill 1 if the collection container lid sensor device 212 malfunctions, and is not immediately dependent on a service technician. Since an incorrectly seated or missing collection container lid 72 serves only to detect an operating error, which is intended to prevent contamination of the grinding chamber 98, but cannot endanger the user because the safety-relevant housing cover 36 remains closed (and no override function is available for it), deactivating the detection of the collection container lid 72 by manual override by the user complies with the Machinery Directive.

[0085] Fig. 26 shows a simplified, exemplary sequence of functions during a grinding process.

[0086] In step 302, the program control waits for the insertion of the complete grinding assembly 74. The touch display 42 can show an animation indicating the sequence in which the grinding rotor 52, the ring sieve 54, the sample collection container 56, and / or the collection container lid 72 should be inserted. These animations can be dynamically adjusted if necessary.

[0087] In step 304, the program control prompts the user via the touch display 42 to close the housing cover 36.

[0088] In step 306, the program control uses the collection container lid sensor device 212 to check whether the collection container lid 72 has been inserted correctly.

[0089] When the program control has determined that the collection container lid 72 has been correctly inserted, the program control in step 308 controls the safety interlock, closing the locking hook of the tether 152.

[0090] When the program control receives the feedback from the safety interlock or the locking mechanism "closed", the program control waits in step 310 for the user to enter the start command.

[0091] After the user has entered the start command on the touch display 42, the program control in step 312 activates the cooling fan 114 and releases safety circuits.

[0092] After the program control receives the "safety ok" signal from the frequency converter, the program control starts the drive motor 102 in step 314.

[0093] After the user-programmed grinding time has elapsed or after the user has entered a stop command for the grinding process, the program control stops the drive motor 102 in step 316.

[0094] After the program control receives the feedback speed "-0" from the frequency converter, the program control checks in step 318 whether an automatic unlocking should take place or whether there is an unlocking command from the user.

[0095] If the result in step 318 is positive, the program control sends an unlock command to the locking mechanism in step 320 and the interlock 152 opens.

[0096] After the safety interlock has reported "open" to the program control, the program control checks in step 322 whether a run-on time is programmed, e.g., as a SOP or through individual user programming. If not, the cooling fan 114 stops and the program control jumps back to the initial step 102 in step 324; if so, the cooling fan 114 continues to operate in step 326 (run-on time).

[0097] In step 328, the program control monitors whether the overrun time has elapsed. If so, the cooling fan 114 is stopped in step 330 and the program control jumps back to the initial step 102.

[0098] Fig. 27Figure 1 shows a rotor mill 1 with an axial first cooling air duct 124, which extends coaxially around the drive motor 102 in an annular shape. The axial first cooling air duct 124 extends cylindrically around the motor housing 122 or the motor housing shell 123. A hollow cylindrical annular space 128, which forms the axial first cooling air duct 124, extends between the drive motor 102 or the motor housing shell 123. The cooling fan 114 blows cooling air from below into the cooling air inlet openings 124a of the axial first cooling air duct 124, and the cooling airflow exits the axial first cooling air duct 124 at upper cooling air outlet openings 124b. From there, the cooling air flow enters the second cooling air channels 132 in the intermediate floor 96 on the engine compartment side and exits into the upper grinding chamber 98 on the grinding chamber side.

[0099] In both embodiments, there is preferably no exhaust opening to the outside of the device housing 30 in the lower motor compartment 134 in the area of ​​the cooling airflow, so that the cooling airflow generated by the cooling fan 114 is forced from the lower motor compartment 134 into the upper grinding chamber 98 with corresponding overpressure. For example, a hermetically sealed sleeve 146 can be arranged around the cooling fan 114 and the electric drive motor 102 in the lower motor compartment 134.

[0100] It is evident to the person skilled in the art that the embodiments described above 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 protection of the claims. 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

1. Laboratory mill (1) for grinding material, in particular a rotor or centrifugal mill, comprising: a housing (30) forming a lower motor compartment (134) and an upper grinding chamber (98), an electric drive motor (102) with a motor shaft (104) arranged in the lower motor compartment (134) of the housing (30), a grinding assembly (74) that can be inserted into the upper grinding chamber (98), which has a grinding rotor (52) that can be rotated by the drive motor (102), a stationary annular counter element (54) that can be arranged around the grinding rotor (52), and a sample collection container (56), wherein the grinding assembly (74) has a central rotor chamber (62) arranged radially inside the stationary annular counter element (54) and a peripheral annular sample collection chamber (64) arranged radially outside the stationary annular counter element (54). definedan electric cooling fan (114) arranged in the area of ​​the lower motor compartment (134), which generates a cooling airflow (138) that flows along the electric drive motor (102) to cool the electric drive motor (102), a control device (142) for controlling the grinding process, and a user input device (40) via which the user can input grinding parameters for the grinding process, wherein the control device (142) is configured to control the grinding process in response to the grinding parameters entered by the user and wherein the control device (142) is configured to control the electric cooling fan (114) independently of the drive motor (102).

2. Laboratory mill (1) according to claim 1, wherein the device housing (30) has a housing cover (36) with which the upper grinding chamber (98) can be closed off from the environment and / or wherein the sample collection container (56) has a collection container cover (72) with which the sample collection container (56) can be closed inside the upper grinding chamber (98), in particular wherein the housing cover (36) has an axial filling funnel (38) and the collection container cover (72) has a central opening (78) into which the filling funnel (38) opens, such that during operation of the laboratory mill (1) the user can feed material to be ground from outside the laboratory mill (1) through the filling funnel (38) and the central opening (78) of the collection container cover (72) into the central rotor chamber (62).

3. Laboratory mill (1) according to one of the preceding claims, wherein the control device (142) is configured to automatically switch the electric cooling fan (114) on and off independently of the drive motor (102).

4. Laboratory mill (1) according to one of the preceding claims, wherein a memory is included in which a run-on time interval can be stored, wherein the control device (142) is configured to allow the electric cooling fan (114) to continue running for the duration of the run-on time interval after the drive motor (102) has been switched off, and to automatically switch off the electric cooling fan (114) after the run-on time interval has elapsed, and / or wherein the control device (142) is configured to allow the electric cooling fan (114) to continue running in a temperature-controlled manner after the drive motor (102) has been switched off.

5. Laboratory mill (1) according to one of the preceding claims, wherein the control device (142) is configured to receive a run-on command entered by the user via the user input device (40) and, in response to the run-on command, to allow the electric cooling fan to continue running for a run-on time interval and only to switch off the electric cooling fan automatically after the run-on time interval has elapsed.

6. Laboratory mill (1) according to one of the preceding claims, wherein a first temperature sensor is included in the area of ​​the sample collection container (56), which detects the temperature of the sample collection container (56) during and after the milling process and / or wherein a second temperature sensor is included in the area of ​​the drive motor (102), which detects the temperature of the drive motor (102) during and after the milling process and wherein the control device (142) reads the first and / or the second temperature sensor in order to obtain temperature measurements from the sample collection container (56) and / or the drive motor (102) during and after the milling process, in particular wherein the control device (142) controls the milling process and / or the electric cooling fan (114) in response to the measured temperature measurements of the sample collection container (56) and / or the drive motor (102).

7. Laboratory mill (1) according to one of the preceding claims, wherein the drive motor (102) with vertically extending motor shaft (104) is installed in the lower motor compartment (134) and has a motor housing (122) with an axially and annularly extending motor housing shell (123), wherein the electric cooling fan (114) is arranged under the drive motor (102), in particular coaxially to the vertically extending motor shaft (104), and wherein the electric cooling fan (114) generates an upwardly directed cooling airflow (138) which flows axially in the motor housing shell (123) and / or upwards on an outside of the motor housing shell (123) to cool the drive motor (102).

8. Laboratory mill (1) according to one of the preceding claims, wherein the motor housing (123) comprises at least one axial first cooling air channel (124) extending axially from bottom to top and directing the cooling air flow (138) from the electric cooling fan (114) axially upwards along the motor housing (123) within the at least one axial first cooling air channel, in particular wherein the at least one axial first cooling air channel (124) is essentially designed as a radially closed cooling air tube extending axially within the motor housing (123), and / or wherein an axial cooling air guide tube (126) extends annularly around the electric cooling fan (114) and / or radially spaced around the drive motor (102), forming an annular space (128) extending axially and annularly around the drive motor (102), wherein the annular space (128) forms a cooling air guide.and the cooling airflow (138) is blown into the annular space (128) by the electric cooling fan (114) and is guided axially upwards along the drive motor (102) within the annular space (128), limited radially inwards and radially outwards.

9. Laboratory mill (1) according to one of the preceding claims, wherein at least a second cooling air channel (132) is included, which leads from the lower motor compartment (134) into the upper grinding chamber (98) and through which the cooling air flow (138) from the lower motor compartment (134) flows into the upper grinding chamber (98), in particular wherein the cooling air flow (138) is guided through the at least one second cooling air channel (132) from the lower motor compartment (134) under the comminution rotor (52) and from there further under the sample collection container (56).

10. Laboratory mill (1) according to one of the preceding claims, wherein the device housing (30) has an intermediate floor (96) between the upper grinding chamber (98) and the lower motor chamber (134), wherein the intermediate floor (96) has a central opening through which a rotor drive shaft (106) extends vertically into the area of ​​the upper grinding chamber (98), in particular wherein the rotor drive shaft (106) and the comminution rotor (52) have complementary drive means (108, 110) such that the comminution rotor (52) can be placed onto the rotor drive shaft (106) from above and can be driven in a rotating manner by the rotor drive shaft (106) by means of the drive means (108, 110), in particular wherein a labyrinth seal (86) is arranged between the comminution rotor (52) and the drive motor (102), which seals the central rotor chamber (62) and / or the peripheral ring-shaped sample collection chamber (64) seals against the lower engine compartment (134),in particular wherein at least a second cooling air channel (132) extends from the lower motor compartment (134) into the upper grinding chamber (98) below the labyrinth seal (86), through which the cooling air flow (138) from the motor housing shell (123) and / or from the at least one axial first cooling air channel (124) is guided into the upper grinding chamber (98), in particular below the labyrinth seal (86), or wherein the cooling air flow (138) from the motor housing shell (123) and / or from the at least one axial first cooling air channel (124) and through the at least one second cooling air channel (132) is forced through the labyrinth seal (86) into the interior of the sample collection container (56).

11. Laboratory mill (1) according to claim 9 or 10, wherein the at least one axial first cooling air channel (124) transitions fluidically into the at least one second cooling air channel (132) between the lower motor compartment (134) and the upper grinding chamber (98), wherein the at least one axial first cooling air channel (124) and the at least one second cooling air channel (132) between the lower motor compartment (134) and the upper grinding chamber (98) together form a cooling air flow system which extends from the electric cooling fan (114) into the upper grinding chamber (98), such that the cooling air flow is guided from the electric cooling fan (114) through the cooling air flow system upwards into the upper grinding chamber (98).

12. Laboratory mill (1) according to one of the preceding claims, wherein the device housing (30) has a housing cover (36) with which the upper grinding chamber (98) can be closed off from the environment, wherein the housing cover (36) has a locking device (152) or interlock which is controlled and / or monitored by the control device (142), wherein the control device (142) is configured to release the locking device (152) or interlock when the drive motor (102) and / or the grinding rotor (52) has come to a standstill, but while the electric cooling fan (114) is still in operation.

13. Laboratory mill (1) according to one of the preceding claims, wherein the device housing (30) has a housing cover (36) with which the upper grinding chamber (98) can be closed off from the environment, wherein the control device (142) is configured to at least partially open the housing cover (36) after the drive motor (102) has been switched off, while the electric cooling fan (114) is still in operation, and / or wherein the device housing (30) has a housing cover (36) with which the upper grinding chamber (98) can be closed off from the environment, wherein the control device (142) is configured to open the housing cover (36) a gap, but not completely, after the drive motor (102) has been switched off, while the electric cooling fan (114) is still in operation, such that the cooling airflow (138) can escape through the gap from the upper grinding chamber (98) into the environment.

14. Laboratory mill (1) for grinding material, in particular a rotor or centrifugal mill, especially according to one of the preceding claims, comprising: a device housing (30) forming a lower motor compartment (134) and an upper grinding chamber (98), an electric drive motor (102) with a motor shaft (104) arranged in the lower motor compartment (134) of the device housing (30), a grinding assembly (74) insertable into the upper grinding chamber (98), which comprises a grinding rotor (52) rotatably driven by the drive motor (102), a stationary annular counter element (54) that can be arranged around the grinding rotor (52), and a sample collection container (56), wherein the grinding assembly (74) has a central rotor chamber (62) arranged radially inside the stationary annular counter element (54) and a peripheral chamber arranged radially outside the stationary annular counter element (54). defined an annular sample collection chamber (64),a cooling fan (114) arranged in the area of ​​the lower motor compartment (134), which generates a cooling airflow (138), a cooling air duct system (124, 132, 136) in which the cooling airflow (138) is directed from the cooling fan (114) along the electric drive motor (102) and to below the sample collection container (56) in order to cool the electric drive motor (102) and the sample collection container (56).

15. Laboratory mill (1) according to one of the preceding claims, wherein the cooling air duct system in the lower motor compartment (134) comprises at least two parallel cooling air paths, in particular wherein the drive motor (102) comprises a motor housing (122) with a motor housing jacket (123) and the first cooling air path comprises at least one axial first cooling air duct (124) in or on the motor housing jacket (123) and / or wherein the drive motor (102) with its motor housing (122) is installed in a vertically extending axial cooling air guide tube (126) which surrounds the motor housing (122) at a radial distance, so that an annular space (128) is formed between the motor housing (122) and the cooling air guide tube (126), wherein the second cooling air path is formed by the annular space (128) between the motor housing (122) and a cooling air guide tube (126).

16. Method for operating a rotor or centrifugal mill, in particular according to one of the preceding claims, comprising the steps of: inserting the grinding assembly (74) into the upper grinding chamber (98), closing the housing cover (36), entering a run-on time or a run-on command for the cooling fan (114) into the user input device (42), entering a start command into the user input device (42) after stopping the drive motor (102), opening the housing cover (36) while the electric cooling fan (114) is still running, and removing at least the sample collection container (56) and the collection container cover (72) from the upper grinding chamber (98), either while the electric cooling fan (114) is still running or after stopping the electric cooling fan (114).

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