Laboratory mill and method for clamping a milling vessel on and / or in a milling vessel holder of a laboratory mill

Abstract

The invention relates to a laboratory mill, in particular a laboratory-scale ball mill, furthermore in particular a centrifugal or planetary ball mill or vibrational mill, having at least one milling vessel holder (1) for holding at least one milling vessel (2) during milling operation of the laboratory mill, in particular wherein the milling vessel holder (1) is designed to hold only one milling vessel (2), and having a clamping unit (4) for clamping the milling vessel (2) in and / or on the milling vessel holder (1), in particular for frictionally clamping to a spindle drive, wherein by transferring a minimum clamping force introduced into the spindle unit (4) and / or an introduced minimum clamping torque from the clamping unit (4) to the milling vessel (2) and / or to the milling vessel holder (1) an operating state of the laboratory mill is defined in which the laboratory mill can be operated as intended. According to the invention, a detection device is provided for qualitative and / or quantitative detection of the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit (4).

Description

[0001] Laboratory mill and method for clamping a grinding bowl to and / or in a grinding bowl holder of a laboratory mill

[0002] The invention relates to laboratory mills, in particular ball mills on a laboratory scale, further in particular centrifugal or planetary ball mills or vibrating mills, with at least one grinding bowl holder for holding at least one grinding bowl during a grinding operation of the ball mill, in particular wherein the grinding bowl holder is designed to hold only one grinding bowl, and with a clamping unit for clamping the grinding bowl in and / or on the grinding bowl holder, in particular for non-positive clamping with a spindle drive, by transmitting a clamping force and / or a clamping torque from the clamping unit to the grinding bowl and / or the grinding bowl holder.By transferring an (axial) minimum clamping force introduced into the clamping unit and / or an introduced minimum clamping torque from the clamping unit to the grinding bowl completely inserted and / or placed in and / or onto the grinding bowl holder and / or onto the grinding bowl holder, an operating state is defined in which the laboratory mill can be operated as intended.

[0003] Furthermore, the invention relates to a method for clamping a grinding bowl on and / or in a grinding bowl holder of a laboratory mill.

[0004] Centrifugal ball mills have grinding bowls arranged eccentrically to a drive axis and guided on a circular path. This prevents the grinding bowl from rotating around its own axis. In contrast, planetary ball mills have a design that allows a combined orbital and rotary motion for the grinding bowls. The rotation of the grinding bowls generates a radially outward-directed centrifugal force on the material to be ground. Unlike centrifugal ball mills, the grinding bowls in a planetary ball mill rotate around their own axes, so that in a planetary ball mill, an additional centrifugal force component is generated that is superimposed on the centrifugal force component generated by the rotation of the grinding bowls around the center axis of the ball mill. In addition, the Coriolis force acts on the grinding bowls.

[0005] Vibrating mills also belong to the ball mill family. The grinding bowls clamped into the mill perform circular oscillations, pulverizing the sample through the impact and friction of the grinding balls. Furthermore, the sample is mixed by the movement of the grinding bowl and the balls.

[0006] During proper operation of the laboratory mills in question, the grinding bowls must be held in a defined, predefined position relative to the rotational or oscillation axes. This requires a certain minimum clamping force and / or a certain minimum clamping torque to be applied to the clamping unit, which can be done manually and / or using a tool as a tightening or opening aid. The clamping unit can have a handle onto which a tool can be positioned. The tool can then be used to tighten the handle of the clamping unit.

[0007] An embodiment of a clamping unit for clamping a grinding bowl in a centrifugal ball mill is disclosed and described in the applicant's DE 20 2008 008 473 U1. This unit has a handle acting on a spindle drive. When the spindle drive is tightened by rotating the handle, the spindle arms rest in recesses of a grinding bowl holder or receiving device for the grinding bowl, causing the spindle drive to press against the grinding bowl, thus securing and fixing it in the grinding bowl holder.

[0008] To ensure a high degree of security against the grinding bowls becoming detached from the laboratory mill during grinding operation, it is necessary to apply a specific minimum clamping force and / or a specific minimum clamping torque to the clamping unit and transfer this force to the grinding bowl and / or the grinding bowl holder. The magnitude of the applied clamping force and / or the applied clamping torque is subject to the subjective perception of the mill operator, who must decide, based on experience and / or purely estimation, whether the applied clamping force and / or the applied clamping torque are sufficient to ensure the grinding bowl is securely held on and / or in the grinding bowl holder during proper operation of the mill.In order to ensure that the ball mill operates as intended when clamping the grinding bowl, it can easily happen that the operator applies too much clamping force and / or too much clamping torque to the clamping unit, which can occur particularly when using a tool to tighten the clamping unit. Applying too much force or torque to the clamping unit can then lead to damage to components of the clamping unit and also requires a lot of effort from the mill operator. If too little clamping force and / or too little clamping torque is applied to the clamping unit in order to avoid damage to components of the clamping unit and to reduce the amount of work, it is not possible to say with great certainty whether the grinding bowl is clamped in the grinding bowl holder as intended.

[0009] The object of the present invention is to provide a laboratory mill with the generic features and a method for clamping a grinding bowl on and / or in a grinding bowl holder of a laboratory mill, wherein the grinding bowl clamping is simple and can be carried out comfortably for an operator and wherein the grinding bowl clamping ensures a high level of operational reliability during grinding operation of the laboratory mill.

[0010] The aforementioned object is achieved by a laboratory mill having the features of claim 1 and by a method for clamping a grinding bowl to and / or in a grinding bowl holder of a laboratory mill having the features of claim 12. Advantageous embodiments of the invention are the subject of the dependent claims.

[0011] To achieve the aforementioned object, the invention proposes a detection device for laboratory mills of the generic type, wherein the detection device is designed for the automatic quantitative and / or qualitative detection of the introduction of a clamping force and / or a clamping torque equal to the minimum clamping force and / or the minimum clamping torque into the clamping unit. When the minimum clamping force and / or the minimum clamping torque are introduced into the clamping unit, it is ensured that, during proper operation of the laboratory mill, the grinding bowls do not become detached from the grinding bowl holder, and the escape of grinding material from the grinding bowl is prevented.The clamping force and / or clamping torque is preferably introduced into the clamping unit manually by actuating the clamping unit, for example by turning a handle of a spindle drive, which presses onto the grinding bowl and secures and fixes it in and / or on the holding device. The spindle drive can preferably be turned using a tool, so that a clamping torque is easily transferred to the spindle drive and, via the spindle drive, to the grinding bowl and / or to the grinding bowl holder. When qualitatively detecting the minimum clamping force and / or the minimum clamping torque, the detection device is designed to detect whether the minimum clamping force and / or the minimum clamping torque has been reached or not. When, on the other hand, the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit is detected quantitatively, the clamping force and / or the introduced clamping torque is determined according to its magnitude.For this purpose, the detection device may comprise at least one force measuring and / or torque measuring device.

[0012] The detection device can have a signal unit designed to generate an optical, acoustic, tactile, and / or electrical signal in response to the detection of the minimum clamping force and / or the minimum clamping torque. By displaying and / or outputting a signal, an operator can be easily informed that the minimum clamping force and / or the minimum clamping torque has been reached upon application of force and / or torque to the clamping unit and that further application of force and / or torque is not necessary. An electrical signal can be generated in response to the application of the minimum clamping force and / or the minimum clamping torque and then converted into a visually, acoustically, or tactilely perceptible signal for the operator.However, a "signal" within the meaning of the invention can also be a visually perceptible change in the position of at least one component and / or component section of the laboratory mill, whereby the change in position is attributable to the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit. The term "signal" is therefore to be understood broadly within the meaning of the invention.

[0013] It is preferred that the detection device has at least one trigger and / or a triggering device with at least one trigger, in particular wherein the trigger is movable and, more particularly, spring-loaded. The trigger assumes a release state in response to the introduction of a clamping force and / or a clamping torque into the clamping unit equal to the minimum clamping force and / or the minimum clamping torque. The term "release state" is to be interpreted broadly within the meaning of the invention.

[0014] The release state can be defined by a specific release position of the trigger, whereby the trigger is moved from a non-release position to the release position as a result of the force and / or torque being applied to the clamping unit. When the trigger reaches the release position, the minimum clamping force and / or torque is reached.

[0015] For example, the trigger can form a mechanical switch that interacts mechanically with components of the control unit. When the minimum clamping force and / or minimum clamping torque is applied to the clamping unit, the trigger moves from a first sound position (zero) to a second sound position or the release position (one). The application of the minimum clamping force and / or minimum clamping torque is then detected by the digital value (zero, one) of a mechanical switch.

[0016] The trigger and the control unit can also form a contactless switch. The contactless switch can be designed as a magnetic switch. The trigger can have at least one magnet, and the control device can have at least one Hall sensor. The release position of the trigger falls within the sensitivity range of the Hall sensor, so that the release state is detected by bringing the magnet into the sensitivity range of the Hall sensor.

[0017] The trigger can also be a light barrier interrupter, and the control device can have a transmitter that emits light. A receiver of the control device, which receives the light emitted by the transmitter, can be provided, thus forming a light barrier. The release position of the trigger can be located in the area of ​​the light barrier, so that the release state is detected by the interruption of the light barrier by the trigger in its release position.

[0018] Alternatively, the release state can also be characterized by a deformation of the trigger as a result of the force and / or clamping torque being applied to the clamping unit. If the trigger reaches a certain degree of deformation, the release state may be present, thus indicating that the minimum clamping force and / or clamping torque has been reached.

[0019] The minimum clamping force and / or minimum clamping torque can then be measured using an analog measuring device, such as a strain gauge. Strain gauges are designed to measure stretching and compression deformations. Strain gauges change their electrical resistance even with slight deformations and are used as strain sensors. In this case, the trigger can be deformed when the minimum clamping force and / or minimum clamping torque is applied, which is detected by the strain gauge.

[0020] Alternatively, the trigger can also be a spring element made of spring steel. The steel can be shaped so that it has a stable and a metastable state, like a cracking frog. The trigger can bear against a movable part of the laboratory mill that is connected to the clamping unit and moves with it when a clamping force and / or clamping torque is applied to the clamping unit, for example against a sun gear of a planetary ball mill on which the grinding bowl holder is arranged. When a clamping force and / or clamping torque is applied to the clamping unit at the level of the minimum clamping force and / or the minimum clamping torque, a relative movement occurs between components of the laboratory mill and the spring element, which can lead to a sudden bending of the spring element, so that a cracking noise can signal to the operator that the minimum clamping force and / or clamping torque has been applied.

[0021] The minimum clamping force and / or the minimum clamping torque introduced into the clamping unit corresponds to the clamping force and / or the clamping torque required to hold the grinding bowl properly, i.e. securely against loss and unintentional escape of grinding material from the grinding vessel, on and / or in the grinding bowl holder during normal operation of the laboratory mill.

[0022] To detect the release state of the trigger, the detection device can comprise a control unit. For example, the control unit can interact with a trigger of the detection unit and form a mechanical or contactless switch, whereby reaching a specific target position and / or a specific adjustment movement of the trigger can be identified by the control unit as the initiation of the minimum clamping force and / or the minimum clamping torque.

[0023] In this context, the control device can interact with a signaling device for generating and / or transmitting a signal, particularly a digital one, in response to the detection of the release state. Furthermore, a control device can be provided to control a drive of the laboratory mill depending on the signal or in response to the detection of the initiation of the minimum clamping force and / or the minimum clamping torque.

[0024] Particularly preferably, after the grinding bowl has been fully inserted into and / or onto the grinding bowl holder, the grinding bowl and / or the grinding bowl holder reaches a target position in which the laboratory mill can be operated as intended. The detection device can be designed to detect the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit after the target position of the grinding bowl and / or the grinding bowl holder has been reached. First, the grinding bowl is preferably fully inserted into the grinding bowl holder until it has reached its target position. Subsequently, clamping is carried out by introducing a preferably manual clamping force and / or a clamping torque into the clamping unit, wherein no further relative movement occurs between the grinding bowl and the grinding bowl holder.

[0025] In this context, the invention also relates to a method for operating a laboratory mill, in particular a ball mill on a laboratory scale, further in particular a centrifugal or planetary ball mill or vibrating mill, with at least one grinding bowl holder for holding at least one grinding bowl during a grinding operation of the ball mill, in particular wherein the grinding bowl holder is designed to hold only one grinding bowl, and with a clamping unit for clamping the grinding bowl in and / or on the grinding bowl holder, in particular for force-fitting clamping with a spindle system, wherein the grinding bowl is completely inserted and / or placed in and / or on the grinding bowl holder and reaches a target position in which the grinding bowl remains during the intended operation of the laboratory mill,wherein, after the grinding bowl has been fully inserted and / or placed on the clamping unit, a minimum clamping force and / or a minimum clamping torque is introduced into the clamping unit, and an operating state of the ball mill is defined in which the ball mill can be operated as intended, and wherein the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit after the grinding bowl has been fully inserted and / or placed on the grinding bowl holder is qualitatively and / or quantitatively detected by a detection device. It is further preferably provided that the clamping unit, the grinding bowl holder, and, preferably, a carrier device connected to the grinding bowl holder, in particular a sun gear of a planetary ball mill, are held or held immovably relative to one another for detecting the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit. This ensures, in particular,that, within the scope of the detection of the minimum clamping force and / or the minimum clamping torque, a clamping force and / or a clamping torque introduced into the clamping unit by an operator can be transmitted from the grinding bowl holder to the carrier device without relative movement.

[0026] It is particularly advantageous if the clamping unit, the grinding bowl holder and, preferably, a carrier device connected to the grinding bowl holder, in particular a sun gear of a planetary ball mill, are subjected to a holding force directed counter to the clamping force introduced into the clamping unit and / or a holding torque directed counter to the clamping torque introduced into the clamping unit, at least until the minimum clamping force and / or the minimum clamping torque is reached, wherein the clamping force introduced manually into the clamping unit and / or the clamping torque introduced is greater than the holding force and / or the holding torque when the minimum clamping force and / or the minimum clamping torque is reached.When the minimum clamping force and / or minimum clamping torque is reached, a relative movement occurs between the component assembly consisting of the clamping unit, grinding bowl holder, and, preferably, the support device on the one hand, and a stationary mill part on the other. The minimum clamping force and / or minimum clamping torque can then be detected in response to this relative movement.

[0027] The clamping unit and / or the grinding bowl holder and / or a carrier device connected to the grinding bowl holder, in particular a sun gear of a planetary ball mill, can be arranged to be linearly adjustable relative to a stationary mill part and / or relative to each other against a counterforce and / or rotatable against a countertorque, wherein upon introduction of a clamping force and / or a clamping torque into the clamping unit which is lower than the minimum clamping force and / or the minimum clamping torque,an adjustment movement and / or rotational movement is prevented by the counterforce and / or the countertorque, and wherein, in response to the introduction of a clamping force and / or a clamping torque into the clamping unit at the level of the minimum clamping force and / or the minimum clamping torque, the counterforce and / or the countertorque is overcome and a linear adjustment and / or rotation of the clamping unit and / or the grinding bowl holder and / or the carrier device relative to the stationary mill part and / or relative to each other takes place, and the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit is detected in response to the linear adjustment and / or rotation.

[0028] It is particularly preferred that the clamping unit, the grinding bowl holder and, preferably, a carrier device connected to the grinding bowl holder, in particular a sun gear of a planetary ball mill, are positively and / or non-positively connected to a stationary mill part of the laboratory mill until a clamping force and / or a clamping torque is introduced into the clamping unit at the level of the minimum clamping force and / or the minimum clamping torque and are immovable relative to the stationary mill part and that when the minimum clamping force and / or the minimum clamping torque is reached, the positively and / or non-positively connected connection is interrupted and the clamping unit, the grinding bowl holder and, preferably, the carrier device are movable relative to the stationary mill part or are moved due to a further force and / or torque introduction into the clamping unit.The detection of the minimum clamping force and / or the minimum clamping torque can then be provided in response to the relative movement.

[0029] In particular, a trigger of the detection device can be subjected to the holding force and / or the holding torque, wherein the trigger assumes a release state when the minimum clamping force and / or the minimum clamping torque is reached, in particular is moved into a release position.

[0030] The trigger can be positively and / or non-positively connected to the clamping unit, the grinding bowl holder, and, preferably, the support device, and can be movably, in particular pivotably, held on a stationary mill part or connected to the stationary mill part. Alternatively, the trigger can also be movably, in particular pivotably, held on the clamping unit, the grinding bowl holder, and / or, preferably, the support device, and is then positively and / or non-positively connected, directly or indirectly, to a stationary mill part until the minimum clamping force and / or the minimum clamping torque is reached. Upon reaching the minimum clamping force and / or the minimum clamping torque, the trigger reaches a release state, which can then be detected by the detection device, for example, with a correspondingly designed control device.The release status can also be perceived visually, acoustically or tactilely by the operator, without additional components of a control unit.

[0031] The trigger can be kinematically coupled to the clamping unit and / or the grinding bowl holder and / or a support device for the grinding bowl holder. A possible movement of the clamping unit, grinding bowl holder, and support device upon reaching the minimum clamping force and / or minimum clamping torque can then lead to a coupled forced movement of the trigger, which can preferably be pivotably and / or linearly adjustable mounted on a stationary mill part.

[0032] In this embodiment, the trigger can be directly connected to the clamping unit and / or the grinding bowl holder and / or, preferably, to the support device for the grinding bowl holder and form a slip or friction clutch connection that is released when the minimum clamping force and / or the minimum clamping torque is reached, enabling relative movement between the components. The trigger can then form a digital switch that can interact mechanically with the control unit to detect the minimum clamping force and / or the minimum clamping torque via a digital value of the switch. A zero position of the switch can be defined by the hold position of the trigger, in which the trigger is positively and / or non-positively connected to the clamping unit and / or the grinding bowl holder and / or the support device, and a release position of the trigger (switch position "one"), in which the slip or friction clutch connection is interrupted.

[0033] The invention particularly preferably relates to a detection device for planetary ball mills. In this case, it can be provided that the grinding bowl holder is connected to a support device, in particular wherein the support device is mounted on a housing of the laboratory mill so as to be rotatable about a central axis, in particular wherein the support device is designed as a sun gear of a planetary ball mill and / or comprises a sun gear, and, further in particular, wherein the grinding bowl holder is mounted so as to be rotatable about a holding axis relative to the support device and is carried along by the support device during normal operation of the laboratory mill.Preferably, the trigger can be kinematically coupled directly to the carrier device, in particular to the sun gear, so that a movement of the grinding bowl holder and / or the carrier device leads to a coupled change in the position coordinates of the trigger, in particular relative to the grinding bowl holder and / or carrier device.

[0034] In the context of the invention, kinematic coupling means that the introduction of a clamping force and / or a clamping torque into the clamping unit leads to a torque transmission via the grinding bowl and the grinding bowl holder into the support device or the sun gear. In this case, the clamping unit, the grinding bowl holder with the fully inserted grinding bowl, and the support device are held in a rotationally fixed manner relative to one another during the introduction of force and / or torque into the clamping unit, thus preventing relative rotation between the grinding bowl holder and the support device during grinding bowl clamping.

[0035] If the minimum clamping force and / or torque applied to the clamping unit is exceeded, this leads to a relative rotation of the support device to the trigger and a deflection of the trigger, which assumes its release position. This is then detected by the control unit. For this purpose, the control unit has components that interact with the trigger, which can form a switch with the trigger.

[0036] For example, the trigger can be held on a stationary mill component, such as a housing part of the laboratory mill, or connected to the stationary mill part, in particular directly or indirectly articulated to the stationary mill part. The trigger can engage with its free end in a recess or external gear toothing of the sun gear if the torque introduced into the clamping unit is less than the minimum clamping torque. Kinematic reversal is possible, in which case the trigger can be held on the sun gear, in particular pivotably articulated. The trigger can then engage in a recess in a mill part that is stationary during operation of the mill if the minimum clamping force introduced into the clamping element or the minimum clamping torque has not yet been reached. The trigger can then be connected to the stationary mill part in a form-fitting and / or force-fitting manner.

[0037] The trigger can be subjected to a counter-torque via a spring means, so that only when the minimum clamping torque is reached is a pivoting movement of the trigger into a release position possible, in which the positive and / or non-positive connection is then interrupted.

[0038] Until the minimum clamping torque is introduced into the clamping unit, the sun gear can be held in a rotationally fixed manner on a fixed mill part of the laboratory mill via the positive and / or non-positive connection with the trigger.

[0039] To ensure that the trigger does not inadvertently come into contact with a mill component that moves during the operating state of the laboratory mill, in particular a support device for the grinding bowl holder, and furthermore in particular the sun gear of a planetary ball mill, a safety device can be provided to hold the trigger in a safety position in which rotation of the sun gear relative to the trigger is possible. For example, the trigger can be spring-loaded, with an electromagnet being provided as the safety device, with which the trigger can be held in the safety position against the spring force of the spring means.

[0040] Furthermore, the laboratory mill can have a plurality of grinding bowls and / or grinding bowl holders, wherein, preferably, each grinding bowl and / or each grinding bowl holder is assigned its own clamping unit, in particular wherein a plurality of grinding bowl holders are connected to a common support device, in particular a sun gear of a planetary ball mill. The detection device can then be selected to detect, for each clamping unit, the introduction of a clamping force and / or a clamping torque into the clamping unit at the level of the minimum clamping force and / or the minimum clamping torque.

[0041] In the previously described embodiment, a common trigger can preferably be provided in order to be able to detect the introduction of a clamping force and / or a clamping torque equal to the minimum clamping force and / or the minimum clamping torque into the respective clamping unit of offset grinding bowl holders with minimal design effort. The grinding bowl clamping in the offset grinding bowl holders then preferably takes place sequentially.

[0042] In an alternative embodiment of the invention, the detection device can have a trigger, wherein the trigger is designed to be movable relative to the clamping unit, the grinding bowl and / or the grinding bowl holder and / or relative to a carrier device connected to the grinding bowl holder, in particular a sun gear of a planetary ball mill, and is held on the clamping unit, the grinding bowl, the grinding bowl holder and / or the carrier device, in particular is integrated into the clamping unit, the grinding bowl, the grinding bowl holder and / or the carrier device, and wherein the trigger is moved relative to the clamping unit, the grinding bowl and / or relative to the grinding bowl holder and / or relative to the carrier device upon introduction of a clamping force and / or a clamping torque in the clamping unit and reaches a target position detectable by the detection device upon introduction of a minimum clamping force and / or a minimum clamping torque.

[0043] The target position can be detected by a control unit, and the trigger can be a digital (mechanical) switch or a contactless switch. The introduction of a clamping force and / or a clamping torque into the clamping unit equal to the minimum clamping force and / or the minimum clamping torque can lead to an adjustment movement of the trigger into a release position, wherein, preferably, the trigger can be visible, at least in part, in the release position to an operator from outside the clamping unit, the grinding bowl holder, and / or the support device. This allows the operator to easily visually check the release position. The release position can also be automatically recorded by a camera device.

[0044] For example, the release mechanism can be integrated into a spindle drive of the clamping unit. For example, spring elements can be provided in a spindle drive of the clamping unit. The spring elements can be preloaded when the spindle drive is tightened, so that a release mechanism is activated or triggered according to the principle of safety elements in trailer couplings. The release mechanism can then extend outward through the pressure piece, at least in part, in the release position. This can be easily perceived by an operator and interpreted as the minimum clamping force and / or minimum clamping torque being reached.

[0045] In a further alternative embodiment, the detection device can have a trigger, wherein the trigger is formed on or rigidly connected to the clamping unit, the grinding bowl and / or the grinding bowl holder and / or to a carrier device connected to the grinding bowl holder, in particular a sun gear of a planetary ball mill, and wherein the trigger is moved together with the clamping unit, the grinding bowl and / or the grinding bowl holder and / or the carrier device when a clamping force and / or a clamping torque is introduced into the clamping unit and reaches a detectable target position when a minimum clamping force and / or a minimum clamping torque is introduced.The trigger can be a specific geometric section of the clamping unit, the grinding bowl, and / or the grinding bowl holder and / or the support device, which travels a specific adjustment path in response to the introduction of the clamping force and / or clamping torque into the clamping unit and reaches a target position upon reaching the minimum clamping force and / or a minimum clamping torque. The trigger can then, in turn, be a mechanical or contactless switch, or the release position can be detected visually and / or with a camera system.

[0046] A further possibility of the invention can provide for the use of a measuring device for the qualitative detection of the minimum clamping force and / or the minimum clamping torque. With a measuring device, compressive forces between the clamping unit, in particular a pressure piece of the clamping unit, and the grinding bowl, in particular a grinding bowl cover, and / or the grinding bowl holder can be directly measured. Pressure sensors can be arranged between the grinding bowl cover and the pressure piece, or also between the grinding bowl base and the grinding bowl holder and / or between the grinding bowl holder and a support device of the mill for the grinding bowl holder, for example, between the grinding bowl holder and a sun gear of a planetary ball mill.

[0047] It is also possible to provide torque sensors to detect the minimum clamping torque, for example, a torque measurement derived from the radius of the sun gear axis of a sun gear of a planetary ball mill can be provided.

[0048] A further alternative embodiment can provide that the detection device comprises a measuring device and that the detection of the minimum clamping force and / or the minimum clamping torque takes place via a measurement of the motor current and / or the motor voltage of a drive motor of a support device for the grinding bowl holder, for example the sun gear of a planetary ball mill, and / or a drive motor of a grinding bowl holder. The torque transmitted by the clamping unit is then determined by measuring the motor current and / or motor voltage. For example, a drive motor for the sun gear can be energized while a housing cover of the laboratory mill is open. The motor locks the sun gear; if the torque transmitted to the sun gear by introducing a clamping torque changes, the motor current or motor voltage changes. When a certain change is reached, it can be concluded that the minimum clamping torque has been introduced.

[0049] The drawings illustrate exemplary embodiments of the invention, which are described below. However, the invention is not limited to the described exemplary embodiments.

[0050] The drawing shows:

[0051] Fig. 1 is a perspective view of a grinding bowl holder of a laboratory mill for a grinding bowl with a clamping unit for clamping the grinding bowl in and / or on the grinding bowl holder;

[0052] Figs. 2-4 schematic representations of a replacement system of a detection device for the qualitative detection of the introduction of a minimum clamping force and / or a minimum clamping torque into a clamping unit of a laboratory mill for the intended operation of the laboratory mill and

[0053] Fig. 5 schematic representations of a replacement system of a sun gear of a planetary ball mill with two grinding bowl holders with different lever positions of a tightening tool used to introduce a clamping force and / or a clamping torque in clamping units of the grinding bowl holders.

[0054] Fig. 1 shows a grinding bowl holder 1 for a grinding bowl 2 with a grinding bowl cover 3, wherein the grinding bowl 2 is clamped via the grinding bowl cover 3 in and / or on the grinding bowl holder 1 with a clamping unit 4. The grinding bowl holder 1 can be rotatably arranged or held on a receiving device or carrier device not shown in Fig. 1. In particular, the grinding bowl holder 1 can be rotatably arranged on a sun gear 5 of a planetary ball mill, shown in Figs. 2 to 5.

[0055] The arrangement of grinding bowl holder 1 , grinding bowl 2 with

[0056] Grinding bowl cover 3 and clamping unit 4 can be part of a centrifugal mill designed as a planetary ball mill, wherein with regard to the further components of such a centrifugal ball mill and their function, reference is made to the disclosure of the generic DE 20 2008 008473 U1 or to the disclosure of DE 197 12 905 C2, from which a person of average skill in the art can gain correspondingly additional knowledge regarding the function of the components of the planetary ball mill.

[0057] The sun gear 5 of the planetary ball mill can be rotatable about a center axis 6 of a housing (not shown) of the planetary ball mill, shown in Figs. 2 to 4. A belt drive 5a can be provided to drive the sun gear 5.

[0058] On the sun gear 5 as a support device, the grinding bowl holder 1 is arranged eccentrically to the central axis 6 as a receiving device for the grinding bowl 2 and is also rotatable about the grinding bowl or planetary axis 7 by means of a correspondingly arranged belt drive 7a, wherein the rotational axis of the grinding bowl holder 1 is arranged eccentrically to the rotational axis of the sun gear 5. In a grinding bowl clamping described below, the grinding bowl holder

[0059] 1 is fixed to the sun gear 5 and is then held non-rotatably on the sun gear 5 during the grinding bowl clamping.

[0060] The clamping unit 4 has, according to Fig. 1, as a pre-tensioning device for the grinding bowl

[0061] 2 with grinding bowl cover 3, a spider 8 with, for example, three spider arms 9, which engage in recesses in tabs 10 of the grinding bowl holder 1. The spider 8 fixed to the tabs 10 thus forms a counterbearing for a spindle drive 11 passing through the spider 8, which acts on the grinding bowl cover 3. The clamping unit 4 is connected in a rotationally fixed manner to the grinding bowl holder via the spider arms 9 engaging in the recesses in the tabs 10 of the grinding bowl holder 1. If the spindle drive 11 is tightened by turning a tightening tool 12 with the clamping force 13 (cf. reference numeral 13 in Fig. 1; manual force F), the spider arms 9 of the spider 8 are supported in the recesses, whereby the spindle drive 11 is pressed onto the grinding bowl cover with an end-side pressure piece 13a.

[0062] 3 and thereby secures and fixes the grinding bowl 2 in the grinding bowl holder 1.

[0063] In the embodiment shown, the grinding bowl 2 is first fully inserted into and / or placed onto the grinding bowl holder 1. The force is then transmitted via the tightening tool 12 to the spindle drive 11 of the clamping unit 4. When the clamping force 13 is introduced into the clamping unit 4, a clamping torque M1 is then transmitted via the tightening tool 12 to the spindle drive 11 and thus a compressive force that acts against the grinding bowl lid 3. If the operator of the laboratory mill applies a clamping torque M1 to the clamping unit 4 via the tightening tool 12 and its clamping force 13, this results in a tightening torque M2 acting on the grinding bowl holder 1.

[0064] For further details of the arrangement shown of grinding bowl holder 1, grinding bowl 2 with grinding bowl cover 3 and clamping unit 4 with spider 8, reference is made to the disclosure of DE 20 2008 008 473 U1.

[0065] In order to ensure that the grinding bowl 2 does not become detached from the grinding bowl holder 1 during normal operation of the laboratory mill and that the grinding bowl cover 3 is sufficiently clamped against the grinding bowl 2, the operator must manually apply a sufficiently high clamping force 13, hereinafter referred to as the "minimum clamping force", and thus a sufficiently high clamping torque M1, hereinafter referred to as the "minimum clamping torque", to the clamping unit 4 or the spindle drive 11 via the tightening tool 12. The minimum clamping torque M1 results in a correspondingly high tightening torque M2 of the grinding bowl holder 1 and, for the operating state in which the grinding bowl holder 1 is held in a rotationally fixed manner relative to the sun gear 5, a correspondingly high torque M3 acting on the sun gear 5.

[0066] In order to give the operator feedback that the minimum clamping force 13 or the minimum clamping torque M1 has been introduced into the clamping unit 4, a detection device 14 is provided.

[0067] 2 to 4, the detection device 14 has a trigger 15, a control unit 16, and a signaling unit 17. In the embodiment shown, the sun gear 5 of the laboratory mill is secured, preferably when the hood is open, by a trigger 15 designed as a pin. The trigger 15 is located on a pivotable holder 18 held on a stationary mill part, which is secured against pivoting by a preloaded spring 19. Due to the spring preload, a holding force or holding torque acts on the holder 18 and thus on the trigger 15. If the clamping torque M1 applied by the operator via the clamping unit 4 is less than the minimum clamping torque M1, the sun gear 5 is positively and non-positively connected to the trigger, and there is no relative movement between the sun gear 5 and the trigger 15.

[0068] If the minimum clamping torque M1 is reached, the resulting torque M3 of the sun gear 5 is greater than the holding torque of the release mechanism 15 set by the spring tension of the spring 19. This then leads to the release of the positive and non-positive connection between the sun gear 5 and the release mechanism 15 and to a relative movement between the sun gear 5 and the release mechanism 15. As a result of the relative movement, the holder 18 pivots against a stop 20 as shown in Fig. 3, which is detected by a switch 21. The switch 21 is connected to the signal unit 17, which generates an optical, acoustic or tactile signal based on a change in the switch position of the switch 21, so that the operator receives feedback about the introduction of the minimum clamping force 13 and / or the minimum clamping torque M1 via the tightening tool 12 into the clamping unit 4.

[0069] For example, the tightening tool 12 can be placed on a handle of the spider 8 and then tightened clockwise. The minimum tightening torque can be between 10 and 50 Nm, for example, 25 Nm.

[0070] The laboratory mill can emit a buzzing tone as an acoustic signal and display a message in the form of a specific symbol on a display when the force or torque limit at which relative movement occurs is reached. The detection of the minimum clamping force 13 ensures, on the one hand, that the spindle drive 11 is sufficiently tightened and, on the other hand, that the clamping force 13 applied manually by the operator when tightening the spindle drive 11 is not excessive.

[0071] Figs. 2 to 4 schematically show an equivalent system of a detection device 16 for qualitatively detecting the introduction of a minimum clamping force and / or a minimum clamping torque into the clamping unit 4, wherein Fig. 2 shows the equivalent system in a state in which the trigger 15 is in a holding state and in positive and / or non-positive engagement with the sun gear 5. Fig. 3 shows a release state of the trigger 15 when the trigger 15 pivots downward due to a sufficiently high torque M3 transmitted to the sun gear 5 against the effect of the holding or counter-torque set by the spring preload of the spring 19 and enters a switching contact (switching state).

[0072] Fig. 4 shows a secured state in which the trigger 15 is held in a decoupling position away from the sun gear 5 by a securing device 22. In the secured state, the positive and / or non-positive connection between the sun gear 5 and the trigger 15 is interrupted regardless of the magnitude of the torque M3 acting on the sun gear 5. For example, the securing device 22 can be formed by an electromagnet 23 held on the holder 18, which pulls the trigger 15 into a position away from the sun gear 5 against the action of a further spring means 24. The securing device 22 ensures that during operation of the laboratory mill, there is no undesired contact between the trigger 15 and the sun gear 5, which could lead to an associated malfunction.

[0073] The level of the holding force or holding torque acting on the release 15 due to the spring preload of the spring 19 must be selected such that the moment equilibrium between the holding torque and the torque M3 of the sun gear 5, which results from the introduction of the clamping force 13 into the clamping unit 4, is only canceled when the minimum clamping force or the minimum clamping torque is introduced into the clamping device 4 and the relative movement between the sun gear 5 and the release 15 and the release of the release 15 occurs.

[0074] Fig. 5 shows that the detected torque M3 of the sun gear 5, which is queried by the switch 21 of the control unit 16, depends not only on the size of the clamping force 13 introduced into the clamping unit 4 but also on the lever position of the tightening tool 12.

[0075] Thus, according to Fig. 5, in the lever position shown on the left, with the same clamping force 13 introduced into the clamping unit 4, a greater torque M3 is introduced into the sun gear 5 than in the lever position shown on the right in Fig. 5. With the same holding force 24 or the same holding torque M4 acting on the trigger 15, the moment equilibrium is already abandoned in the lever position of the tightening tool 12 shown on the left in Fig. 5 with a lower clamping force introduced into the clamping unit 4, and as a result, a relative movement between the sun gear 5 and the trigger 15 and the release of the trigger 15 occurs than in the lever position shown on the right in Fig. 5. In order to ensure that the detection device 14 shown does not detect an excessively low clamping force or clamping torque introduced into the clamping unit 4 as the “minimum clamping force” or “minimum clamping torque”, the required level of the minimum holding force 24 orthe minimum holding torque M4 with which the trigger 15 must be acted upon, at a lever position of the tightening tool 12 at which a maximum possible torque M3 is introduced into the sun gear 5 at a certain clamping force.

[0076] Not shown in detail is that the detection device can also comprise a measuring device designed for the qualitative detection of the minimum clamping force and / or a minimum clamping torque. For example, direct measurement of compressive forces can be provided by a pressure sensor arranged between the pressure piece 13a of the clamping unit 4 and the grinding bowl cover 3. Furthermore, alternatively or additionally, a trigger can be integrated into the force transmission path, for example from the spindle drive 11 to the grinding bowl cover 3, wherein spring elements are pretensioned when the spindle drive 11 is tightened, so that the trigger is actuated or triggered according to the principle of safety elements in trailer couplings and assumes a release position when the minimum clamping force and / or the minimum clamping torque is reached.In the release position, the trigger can then generate a feedback signal and / or protrude outwards through the spindle drive 11 in certain areas, so that an operator can interpret the protrusion of the trigger from the spindle drive 11 as an indication that the minimum clamping force and / or the minimum clamping torque has been introduced into the clamping unit 4.

[0077] List of reference symbols:

[0078] 1 grinding bowl holder 13 clamping force

[0079] 2 Grinding bowl 13a Pressure piece 3 Grinding lid 14 Detection device

[0080] 4 clamping unit 20 15 trigger

[0081] 5 Sun gear 16 Control unit

[0082] 5a Belt drive 17 Signal unit

[0083] 6 Center axis 18 Mount 7 Planetary axis 19 Spring element

[0084] 7a Belt drive 25 20 stop

[0085] 8 spider 21 switch

[0086] 9 spider arms 22 safety device

[0087] 10 Tabs 23 Electromagnet 11 Spindle drive 24 Spring element

[0088] 12 tightening tools

Claims

Patent claims:

1. Laboratory mill, in particular a ball mill on a laboratory scale, further in particular a centrifugal or planetary ball mill or vibrating mill, with at least one grinding bowl holder (1) for holding at least one grinding bowl (2) during grinding operation of the laboratory mill, in particular wherein the grinding bowl holder (1) is designed to hold only one grinding bowl (2), and with a clamping unit (4) for clamping the grinding bowl (2) in and / or on the grinding bowl holder (1), in particular for force-locking clamping with a spindle drive (11), wherein by transmitting a minimum clamping force introduced into the clamping unit (4) and / or a minimum clamping torque introduced from the clamping unit (4) to the grinding bowl (2) and / or to the grinding bowl holder (1), an operating state of the laboratory mill is defined in which the laboratory mill can be operated as intended, characterized in thatthat a detection device (14) is provided for the qualitative and / or quantitative detection of the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit (4).

2. Laboratory mill according to claim 1, characterized in that after the grinding bowl (2) has been fully inserted into and / or onto the grinding bowl holder (1), a target position of the grinding bowl (2) and / or the grinding bowl holder (1) is reached, in which position the laboratory mill can be operated as intended, and in that the detection device (14) is designed to detect an introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit (4) after the target position of the grinding bowl (2) and / or the grinding bowl holder (1) has been reached.

3. Laboratory mill according to claim 1 or 2, characterized in that the clamping unit (4), the grinding bowl holder (1) and, preferably, a carrier device connected to the grinding bowl holder (1), in particular a sun gear (5) of a planetary ball mill, are held or held immovably relative to one another for detecting the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit (4).

4. Laboratory mill according to one of the preceding claims, characterized in that the clamping unit (4), the grinding bowl holder (1) and, preferably, a carrier device connected to the grinding bowl holder (1), in particular a The sun gear (5) of a planetary ball mill, at least until the minimum clamping force and / or the minimum clamping torque is reached, is subjected to a holding force directed opposite to the clamping force introduced into the clamping unit (4) and / or a holding torque directed opposite to the clamping torque introduced into the clamping unit (4), and that when the minimum clamping force and / or the minimum clamping torque is reached, the introduced clamping force and / or the introduced clamping torque is greater than the holding force and / or the holding torque.

5. Laboratory mill according to claim 4, characterized in that the clamping unit (4), the grinding bowl holder (1) and, preferably, a carrier device connected to the grinding bowl holder (1), in particular a sun gear (5) of a planetary ball mill, are positively and / or non-positively connected to a stationary mill part of the laboratory mill until a clamping force and / or a clamping torque amounting to the minimum clamping force and / or the minimum clamping torque is introduced into the clamping unit (4) and are immovable relative to the stationary mill part, and that when the minimum clamping force and / or the minimum clamping torque is reached, the positively and / or non-positively connected connection is released and the clamping unit (4), the grinding bowl holder (1) and, preferably, the carrier device are movable relative to the stationary mill part, in particular relative to a trigger (15) of the detection device (14).

6. Laboratory mill according to claim 4 or 5, characterized in that a trigger (15) of the detection device (14) is subjected to the holding force and / or the holding torque and that the trigger (15) assumes a release state, in particular is moved into a release position, when the minimum clamping force and / or the minimum clamping torque is reached.

7. Laboratory mill according to one of the preceding claims, characterized in that the grinding bowl holder (1) is connected to a support device, in particular wherein the support device is mounted on a housing of the ball mill so as to be rotatable about a central axis, in particular wherein the support device is designed as a sun gear (5) of a planetary ball mill and / or has a sun gear (5), and, further in particular, wherein the grinding bowl holder (1) is mounted so as to be rotatable about a holding axis to the support device and is carried along by it during normal operation of the laboratory mill, and that, preferably, the trigger (15) is preferably kinematically coupled directly to the support device, in particular to the sun gear (5).

8. Laboratory mill according to one of the preceding claims, characterized in that a plurality of grinding bowls (2) and / or grinding bowl holders (1) are provided, wherein, preferably, each grinding bowl (2) and / or each grinding bowl holder (1) is assigned its own clamping unit (4), in particular wherein a plurality of grinding bowl holders (1) are connected to a common carrier device, in particular a carrier device with the features of claim 7, and wherein the detection device (14) is designed to detect, for each clamping unit (4), the introduction of a clamping force and / or a clamping torque into the clamping unit (4) at the level of the minimum clamping force and / or the minimum clamping torque, and wherein, preferably, a common trigger (15) is provided to detect, for each clamping unit (4), the introduction of a clamping force and / or a clamping torque into the respective clamping unit (4) at the level of the minimum clamping force and / or the minimum clamping torque.

9. Laboratory mill according to one of the preceding claims, characterized in that the detection device (14) has a trigger (15), wherein the trigger is designed to be movable relative to the clamping unit (4), the grinding bowl (2) and / or the grinding bowl holder (1) and / or relative to a carrier device connected to the grinding bowl holder (1), in particular a sun gear (5) of a planetary ball mill, and is held on the clamping unit (4), the grinding bowl (2), the grinding bowl holder (1) and / or the carrier device, in particular is integrated into the clamping unit (4), the grinding bowl (2), the grinding bowl holder (1) and / or the carrier device, and wherein the trigger (15) upon introduction of a clamping force and / or a clamping torque into the clamping unit (4) relative to the clamping unit (4),to the grinding bowl (2) and / or relative to the grinding bowl holder (1) and / or relative to the carrier device and reaches a detectable target position upon introduction of a minimum clamping force and / or a minimum clamping torque.

10. Laboratory mill according to one of the preceding claims, characterized in that the detection device has a trigger, wherein the trigger is formed or rigidly connected to the clamping unit (4), the grinding bowl (2) and / or the grinding bowl holder (1) and / or to a carrier device connected to the grinding bowl holder (1), in particular a sun gear (5) of a planetary ball mill, and wherein the trigger, upon introduction of a clamping force and / or a clamping torque into the clamping unit (4), together with the clamping unit (4), the grinding bowl (2) and / or the grinding bowl holder (1) and / or the carrier device is moved and reaches a detectable target position when a minimum clamping force and / or a minimum clamping torque is applied.

11. Laboratory mill according to one of the preceding claims, characterized in that the detection device has a measuring device for the qualitative detection of the minimum clamping force and / or a minimum clamping torque, wherein, preferably, the detection of the minimum clamping force and / or a minimum clamping torque takes place via a measurement of the motor current and / or the motor voltage of a drive motor of the carrier device and / or wherein the measuring device is integrated into a pressure piece of the clamping unit (4).

12. Method for clamping a grinding bowl (2) on and / or in a grinding bowl holder (1) of a laboratory mill, in particular a ball mill on a laboratory scale, further in particular a centrifugal or planetary ball mill or vibrating mill, with at least one grinding bowl holder (1) for holding at least one grinding bowl (2) during grinding operation of the laboratory mill, in particular wherein the grinding bowl holder (1) is designed to hold only one grinding bowl (2), and with a clamping unit (4) for clamping the grinding bowl (2) in and / or on the grinding bowl holder (1), in particular for force-fitting clamping with a spindle drive, wherein the grinding bowl (2) is completely inserted and / or placed in and / or onto the grinding bowl holder (1) and reaches a target position in which the grinding bowl (2) remains during the intended operation of the laboratory mill,wherein, after the grinding bowl (2) has been fully inserted and / or placed on the clamping unit (4), a minimum clamping force and / or a minimum clamping torque is introduced into the clamping unit (4) and an operating state of the ball mill is defined in which the ball mill can be operated as intended, and wherein the introduction of the minimum clamping force and / or the minimum clamping torque into the clamping unit (4) after the grinding bowl (2) has been fully inserted and / or placed on the clamping unit (4) is detected qualitatively and / or quantitatively by a detection device.

Images